Scipedia: Documents published in 2018

Numerical analysis of of repair and reinforcement of structures with FRP

Alex Barbat — Mon, 07 May 2018 15:08:09 +0200

In this chapter, we present a procedure to evaluate the local damage and global damage in structures subjected to static and dynamic actions, with special emphasis on the seismic problem. In addition to the formulation for the evaluation of damage, we introduce the concept of reinforcement and structural repair by using laminated epoxy matrix composites with carbon fiber reinforcement. For this purpose, the theory of mixtures is used to define a composite material from its basic components. Damage is also evaluated in these reinforced and/or repaired structures and the influence of these improvements on the overall damage assessment of the structure is discussed.

Revealing the Impact of Small Disasters to the Economic and Social Development

Alex Barbat — Mon, 07 May 2018 10:34:03 +0200

This chapter presents the results of the evaluation of the proneness of Colombia to small scale and chronic disasters, and the type of impact they have for the local and country development. This analysis detected the spatial variability and dispersion of vulnerability and risk in the country because of events that rarely enter the international or even national disaster databases. But these events pose an accumulative development problem for local areas and, given their overall probable impacts, for the country as a whole. First, the database of small disasters used is described to identify the strengths and weaknesses of the available data and how that information was prepared for this research. A conceptual framework regarding the impact of small disasters is then presented, to characterize the risk associated to this type of disasters together with a quantification of their effects and their economic costs in order to illustrate their relevance due to the accumulated impact and recurrence. Finally, the conclusions of the study are given, which identify new risk concepts: The concept of ‘intensive risk’ to refer to the concentrated risk manifesting infrequently in specific locations, and the concept of ‘extensive risk’ to refer to the diffuse risk manifesting frequently over wide territories.

Holistic Urban Seismic Risk Evaluation of Megacities: Application and Robustness

Alex Barbat — Mon, 07 May 2018 10:06:39 +0200

From a holistic perspective, disaster risk requires a multidisciplinary evaluation that takes into account not only the expected physical damage, the number and type of casualties or economic losses, but also the conditions related to social fragility and lack of resilience conditions, which favor the second order effects when a hazard event strikes an urban center. In this chapter, the urban risk is evaluated using composite indicators or indices. Expected building damage and losses in the infrastructure, obtained from loss scenarios are basic information for the evaluation of the physical risk index in each unit of analysis. The holistic evaluation of disaster risk is achieved affecting the physical risk with an impact factor, obtained from contextual conditions, such as the socioeconomic fragility and the lack of resilience, that aggravate the physical risk. Available data about these conditions at urban level are necessary to apply the method. The model is explained and the benefits of this approach are illustrated, inviting to the risk management of urban centers.

Neuro-fuzzy assessment of building damage and safety after an earthquake

Alex Barbat — Sun, 06 May 2018 19:16:41 +0200

This chapter describes the algorithmic basis of a computational intelligence technique, based on a neuro-fuzzy system, developed with the objective of assisting nonexpert professionals of building construction to evaluate the damage and safety of buildings after strong earthquakes, facilitating decision-making during the emergency response phase on their habitability and reparability. A hybrid neuro-fuzzy system is proposed, based on a special three-layer feedforward artificial neural network and fuzzy rule bases. The inputs to the system are fuzzy sets, taking into account that the damage levels of the structural components are linguistic variables, defined by means of qualifications such as slight, moderate or severe, which are appropriate to handle subjective and incomplete information. The chapter is a contribution to the understanding of how soft computing applications, such as artificial neural networks and fuzzy sets, can be used to complex and urgent processes of engineering decision-making, like the building occupancy after a seismic disaster.

Seismic Evaluation of Low Rise RC Framed Building Designed According to Venezuelan Codes

Alex Barbat — Sat, 05 May 2018 20:41:15 +0200

This chapter uses a mechanical method that involves non-linear analysis with deterministic and probabilistic approaches, as well as procedures of analysis based on limits states defined by displacements, in order to evaluate the behavior of a low rise RC building with plan irregularity designed according to Venezuelan codes and subjected to seismic actions. By using adequate structural models and computational tools, the seismic behavior of the building is obtained in a suitable way. Among these tools, the quadrants method was chosen, which provides the rapid assessment of the seismic capacity of a structure through its non-linear response. The results of the research show that the current design of this kind of structures is not safe when they are designed for the maximum seismic actions prescribed by codes. Therefore, it is necessary to review the design procedures in order to fulfill the goals of the performance-based design.

Monte Carlo analysis of structural systems using neural networks

Alex Barbat — Sat, 05 May 2018 19:42:50 +0200

Monte Carlo simulation is increasingly being used in the analysis of large and complex structural systems for the assessment of the uncertainty spread and the reliability. A major handicap for the popularization of this technology is the large number of deterministic evaluations needed to such purposes, inasmuch as linear or nonlinear finite element solvers are required for each output sample
calculation. In order to simplify this task neural networks are evaluated in this paper as a partial surrogate of the deterministic solver. The neural networks are trained with the input/output pairs resulting from a few number of finite element simulations, and are henceforth used in a Monte Carlo context. It is shown that when employed in this way, neural networks constitute a promising tool for a drastic reduction of the computational cost needed by a Monte Carlo simulation in this field of application. Three types of networks have been selected for the study, two of which correspond to supervised and the other one to hybrid learning procedures. The paper compares the network designs in their more relevant aspects, which are the training speed and accuracy, the extrapolation ability and the accuracy of the estimated probabilities.

Soil-structure-fluid seismic interaction

Alex Barbat — Fri, 04 May 2018 18:56:11 +0200

The behavior of structures subjected to earthquakes demonstrates that the phenomena of soil-structure and fluid-structure interaction have a great influence on the structural response, especially in the case of structures such as dams, tanks, elevated water tanks, marine platforms, intake towers, etc. The numerical study of these phenomena requires solving problems in which the coupling between two solids or between a solid and a fluid occurs only at the surfaces of contact between them. This chapter describes several numerical procedures used to solve the problem of seismic interaction. For this, it is necessary to have a record of seismic motion on the interface that separates the area of the soil considered in the analysis, which defines a theoretical surface sometimes called base rock. Below this, the soil can be assumed infinitely stiff or with a certain flexibility. To obtain an accelerogram at the level of the base rock, a deconvolution of the seismic motion available on the ground surface must be made. Then, this calculated accelerogram is applied on the soil-structure-fluid system.

Seismic risk of structures

Alex Barbat — Fri, 04 May 2018 16:38:51 +0200

From the perspective of disasters, risk has been defined in order to carry out its management, as well as to control the possible economic, social and environmental consequences that may occur in a specific area and time. This means that to estimate the risk it is necessary to take into account, from a multidisciplinary point of view, not only the expected physical damage, the victims or equivalent economic losses, but also social, organizational and institutional factors related to the development of the communities. At the urban level, for example, vulnerability, as an internal risk factor, must be related not only to the exposure of the material context or its physical susceptibility to being affected, but also to the social fragilities and the lack of resilience of the communities. In this chapter, conceptual, theoretical and practical problems related to seismic risk are presented. The definitions of hazard and seismic vulnerability, necessary to analyze the risk, are introduced. All the developments that are carried out are examined from the point of view of the possibilities of preventing seismic risk.

Nonlinear structural dynamics

Alex Barbat — Fri, 04 May 2018 15:51:13 +0200

When solving dynamic problems, it is necessary to define in some way the damping of the structure. Generally, a damping term that depends on the velocities is incorporated directly into the dynamic equilibrium equation. To do this, we define a structural damping matrix, such as Rayleigh's, which is quite difficult to estimate. Once the damping has been defined, the problem is solved as a linear elastic one, what enters in contradiction with the fact that a dissipative phenomenon is being treated. In this chapter, an alternative with greater conceptual basis is described, which considers the structural damping based on a viscoelastic constitutive models in which the stress depends in some way on the strain velocity. In this way, the term of structural damping arises directly in the dynamic equilibrium equation, where the properties of the materials can be determined through simple laboratory tests.

Fundamenteal aspects of the seismic design codes

Alex Barbat — Fri, 04 May 2018 15:19:32 +0200

The earthquake resistant design codes in force in the different countries are applied to the field of building structures. However, some of the standards give a certain appearance of "generality" that can give the impression that these are mandatory for any type of structure. In fact, the rules are general only in the definition of the seismic hazard of the area to which they apply, that is, in relation to the maximum ground acceleration. However, in each country, there are other specific codes for the design of non-building structures. This chapter describes the dynamic calculations foreseen in the building seismic design standards; the use of simplified, shear building models; the usual procedure of dynamic calculation of structures based on modal analysis; and, finally, the use of linear and non-linear response seismic spectra, which provides only the maximum response of the structure.

La intensitat inversora de Catalunya i els mercats potencials de futur des de la perspectiva de la implantació

Daniel Quer — Thu, 03 May 2018 22:26:02 +0200

Esperonades per la profunditat de la crisi econòmica a Espanya i a la Unió Europea, les empreses catalanes han augmentat sensiblement la diversificació geogràfica de les seves implantacions internacionals. No obstant, cal esbrinar si l’esforç inversor i d’implantació s’està produint en destinacions (països i regions) que permetin aprofitar les dinàmiques de creixement en els mercats internacionals amb major potencial. Amb aquesta finalitat s’ha calculat i analitzat l’índex d’intensitat inversora de Catalunya per a 86 països i 10 regions mundials, i s’ha avaluat l’atractiu que presenten 105 països des de la perspectiva de la implantació. L’estudi conclou amb una proposta sobre les destinacions (països i regions) que presenten un major potencial de futur per a les implantacions de les empreses catalanes.

Computational simulation of the seismic response of buildings with energy dissipating devices

Alex Barbat — Thu, 03 May 2018 16:15:51 +0200

In this work, the nonlinear dynamic response of RC buildings with energy dissipating devices is studied using advanced computational techniques. A fully geometric and constitutive nonlinear model is used for describing the dynamic behavior of structures. The equations of motion are expressed in terms of cross sectional forces and strains and its weak form is solved using the displacement based finite element method. A suitable version of Newmark’s scheme is used in updating the kinematics variables in a classical Newton type iterative scheme. Material points of the cross section are assumed to be composed of several simple materials with their own constitutive laws. The mixing theory is used to treat the resulting composite. A specific finite element based on the beam theory is proposed for the dissipators including constitutive relations. Finally, several numerical tests are carried out to validate the proposed model.

PROBABILISTIC ASSESSMENT OF THE SEISMIC PERFORMANCE OF STEEL BUILDINGS DESIGNED ACCORDING TO THE LRFD SPECIFICATION

Alex Barbat — Thu, 03 May 2018 12:28:13 +0200

Seismic regulations and building codes experienced major advances in the last decades. Nevertheless, current trends in earthquake engineering are the assessment of the computational procedures provided by such design rules, by using probabilistic techniques, in order to test the anticipated levels of reliability and performance of the structures. While some consideration is given in codes to the uncertainties associated to the seismic action, no probabilistic requirements are posed on the responses, which determine the final design. Consequently, the risk associated to the design formulas remains unknown. The objective of this chapter is to study whether steel buildings designed and constructed according to the Load and Resistance Factor Design (LRFD) specification for Structural Steel Buildings, reasonably meet the probabilistic requirements on structural member safety applying non-linear dynamic analyses and Monte-Carlo techniques. Starting from a specific low-rise braced frame steel building existing in Manizales, Colombia, we also analyze mid-rise and high-rise braced frame buildings. Similar low- mid- and high-rise Moment-resisting frame buildings are also studied. For each building we performed more than ten thousand dynamic simulations, covering a wide range of combinations of demand and strength. In this way, we determine the exceedance probability of the construction capacity and we verify the safety and reliability of the structural members of the buildings. In the analysis of demand, we consider the probabilistic variation of the vertical gravity loads as well as of the seismic horizontal ones. The analyses of the strength of the studied buildings take into account the uncertainties and probability distributions of several parameters as: the yielding strain, the elasticity modulus, the cross-sectional area and their inertia moments. The analysis shows that in the cases here analyzed, but especially in moment-resisting frame buildings, the uncertainties in the input parameters may lead to significant failure probabilities. We conclude that braced frame steel buildings fulfil the seismic safety requirements while moment-resisting frame buildings would require a safety factor of about 2.7 for the column anchorages to the foundations.

Evaluation of the seismic hazard of Barcelona and its application to the estimation of the seismic risk of the city

Alex Barbat — Wed, 02 May 2018 15:48:59 +0200

In the present work, the main steps used in the probabilistic estimation of the seismic hazard of the city of Barcelona, Spain, are described, and it is mentioned how the hazard was used in the probabilistic estimation of the seismic risk of the city. For comparative purposes, the seismic hazard of Barcelona was estimated both in terms of exceedance rate of the macroseismic intensities, and in terms of exceedance rate of the maximum ground acceleration (PGA). In the estimation, the computer code CRISIS2008 (Ordaz et al., 2008) was used, which is based on the methodology proposed by Cornell (1968) and Esteva (1970). This code incorporates valuable tools that allow estimates of seismic hazards to be made at an important level of detail. According to the results, in Barcelona, the PGA value equal to 85 cm/s2, has an average return period of 475 years. The results obtained in terms of macroseismic intensities, indicate that the intensity that has an average a return period of 475 years corresponds to a value between VI and VII. The seismic hazard curves in terms of macroseismic exceedance rates were obtained with the aim of being used in the estimation of the seismic risk of the city by means of the probabilistic method of vulnerability indices (Aguilar, 2011). According to the results, in the city there are buildings with a high level of seismic risk. This is because, despite the fact that Barcelona is located in a zone of low to moderate seismicity, there is a significant percentage of buildings with significantly high levels of seismic vulnerability. The seismic risk curves obtained are expressed in terms of exceedance frequencies of the degrees of seismic damage.

Analysis of an experimental composited joint of RC column and beams-steel column for frames using correlation of digital images

Luisa Casadei — Tue, 01 May 2018 19:19:01 +0200

This research presents the behavior of a real scale experimental column-beam joint formed by three reinforced concrete elements, 1 column and 2 beams, attached to a structural steel column in the upper level is studied. The specimen in question was subjected to the action of cyclic loads in a single direction, in a pseudostatic test for 5000 s, in order to observe which element of the specimen failed and which the failure mode was. The investigation was based on the use of digital images taken throughout the test, during the loading and unloading cycles, each photo being analyzed with the CORRELI-Q4 subroutine, in order to visualize the places where cracking occurs in the concrete. The use of the application allowed to reveal how cracking in the reinforced concrete occurred during the test, and that the column of reinforced concrete was the one that was most affected by cracking, with cracks just below the concrete beams.

Economic and Political Globalization

Daniel Quer — Sun, 29 Apr 2018 23:46:01 +0200

This paper surveys opposing interpretations of globalization of the late twentieth and early twenty-first century. Since there are multiple definitions of globalization it focuses mainly on economic globalization and political globalization. It argues that the economic benefits of globalization are not evenly distributed, with China being among the winners within the developing world. Unskilled workers in the de-industrializing developed nations are among the losers; they fuel protectionist political discourses and have helped Trump become the US President. This paper also argues that in a globalized world liberal democracy has two main competitors as ideal types of political regimes, namely Chinese market-oriented authoritarianism and Russian/Turkish style illiberalism. This paper also reasserts the prevalence of the State. Nationalist movements in Europe, such as the ones in Scotland or Catalonia, desire their own states for reasons that are not alien to globalization. Also the State seems to be the necessary instrument to fight effectively against the main negative effects of economic globalization: climate change and the destruction of the environment.

Numerical modelling of railway ballast behaviour using the Discrete Element Method (DEM) and spherical particles

Joaquín Irazábal González — Fri, 27 Apr 2018 12:50:02 +0200

In the last two decades there has been a great development of high-speed train lines. This advance has led to more demanding loads in railway infrastructures and the appearance of a new problem called ballast flight that happens when some stones rise when the train passes. For these reasons, the development of an application that allows the numerical modelling of the ballast superstructure under different stresses can be very useful, as it will enable design optimization. The DEM is being considered an effective and powerful method for the calculation of engineering problems with granular and discontinuous materials. Railroad ballast layer consists of discrete aggregate particles, so that DEM is one of the most suitable ways to simulate the behavior of particulate ballast material. However, the computational cost of contact calculation between irregular particles is high and limits the calculation capability. From the point of view of micro-scale analysis, it is essential to represent the exact geometry of the particle. On the other hand, if the interest lies in the behavior of the granular material as a whole, the geometry is not a determining factor. Besides that, setting up a simulation of granular material taking care of the exact geometry of each particle will not be efficient. Current work presents the methodology followed to achieve accurate results in the calculation of railway ballast behaviour using DEM and spherical particles. The use of spherical particles reduces the computational cost and makes the simulation set up efficient. Validation results for the calculation of the lateral resistance force against a sleeper moving inside a ballast bed are presented. Regarding ballast flight problem, some high speed ballast collision calculations have also been performed.

Numerical modelling of landslides in reservoirs using the particle finite element method and a non Newtonian Bingham model

Joaquín Irazábal González — Fri, 27 Apr 2018 12:47:02 +0200

Landslides in reservoirs constitute one of the main threats to dams. Although they are not frequent, they may generate severe damages in the population and goods placed near the shores. It is a complex phenomenon, because of the interaction between the landslide, the still water in the reservoir, and the dam. The Particle Finite Element Method (PFEM) is an innovative numerical scheme which combines a lagrangian approach with the resolution of FEM equations via mesh generation. In previous works, it had been applied to the simulation of landslides in reservoirs, considering the moving body either as a rigid solid or as a Newtonian fluid. Despite the promising results of the simulation of some reference cases, these constitutive models showed poor performance when applied to other relevant events, such as Vaiont case. Current work introduces the implementation of a non Newtonian Bingham model in the particle finite element method scheme, and the results of its application to several benchmark cases. Some of them have been used to calibrate the parameters of the Bingham model, whereas others served as test cases. The phenomenon presents several intrinsic uncertainties, such as the lack of precise information about the physical properties of the landslide, its geometry, its granulometry, the drag coefficient along the sliding surface, among others. In spite of that, results show that the Bingham model implemented can be useful for estimating the potential consequences of landslides in reservoirs. This implementation makes the PFEM a versatile numerical tool for the analysis of landslides in reservoirs, provided that from now on both rigid solids, Newtonian and non Newtonian fluids can be accounted for. The authors are currently working in the optimization of the numerical code, so that more complex problems could be afforded in more detail. In addition, the erosion module is being validated, in order to reproduce effects such as the dragging of the underlying material due to the landslide, as well as the effect of overtopping on dam stability, particularly for rockfill dams.

Scenarios of seismic impact

Alex Barbat — Wed, 25 Apr 2018 17:14:02 +0200

In this chapter, the concept of seismic risk is introduced and a review of its historical evolution is made. The number of seismic catastrophes has also been increasing in the twentieth century while the number of earthquakes with destructive capacity remains constant. This must be correlated with the growth of the world's population and with the increasing extension of urban areas in the seismic regions of the world. In these areas, coexist buildings designed by applying advanced standards, with old buildings, without any seismic design. There are also more and more catastrophes of another origin, related to storms, floods, droughts, effects of human activity on the environment, etc. It is very relevant that the increase in seismic risk occurs in the conditions in which seismic standards are continuously improving in all countries. Finally, the authors introduce the concept of seismic scenario and show examples of application for the city of Barcelona, Spain.

Editorial: Evitar el plagio. Respetar la autoría

Luisa Casadei — Wed, 25 Apr 2018 09:10:22 +0200

EDITORIAL: EVITAR EL PLAGIO. RESPETAR LA AUTORIA

Confinement and ductility of reinforced concrete buildings

Alex Barbat — Tue, 24 Apr 2018 16:08:26 +0200

This monograph focuses on an eminently practical issue, which allows to take advantage of the characteristics associated with high ductility steels: the confinement of concrete. An adequate disposition, not only of the transversal reinforcement, but also of the longitudinal reinforcement itself, can considerably increase the performance of the structures. This fact is something fundamental when the structures are subjected to actions close to the collapse situations, as it happens in the case of some earthquakes. Given the importance of this last aspect, as well as the increasing importance that issues related to the earthquake are beginning to have in Spain, this monograph analyzes which are the most appropriate structural typologies in these situations, and what is the contribution of high ductility steel to the improvement of its behavior. The result does not shows excessive surprises. The structurally "more robust" typologies are those constituted by moment resisting frames, consisting of a network of beams and columns. Other typologies, commonly used in our country, such as the structures with columns and slabs, or with flat beams, remain on the side of insecurity. The contribution of high ductility steels is very favorable in the case of the appropriate typologies, while it is insufficient to resolve the bad seismic behaviour of the "more sensitive" typologies.

La contribució d’una gestió eficient dels residus al foment de l’economia circular

Josep Maria Tost — Tue, 24 Apr 2018 13:32:02 +0200

L'economia circular és un model econòmic i productiu que estableix que qualsevol residu és un recurs. Aplicant les seves bases, aconseguim:

* Millorar els resultats econòmics reduint l'ús dels recursos
* Identificar i crear noves oportunitats de creixement econòmic
* Garantir la seguretat del subministrament de recursos essencials
* Lluitar contra el canvi climàtic (un 3% del factor climàtic té a veure amb la gestió de residus)

A Catalunya s’ha plantejat un horitzó del 60% de recollida selectiva per a 2020 i, tenint en compte que actualment s’està en el 38% de, cal avançar en les estratègies per millorar aquests resultats. Les administracions, les empreses i la societat en general són claus per tal d’assolir un circularitat dels residus com a recursos.

A partir del darrer quart del segle XX, a mida que la societat ha anat prenent consciència que determinades pràctiques acabaven tenint un efecte bumerang negatiu, és quan s’ha començat a articular un discurs i a adoptar unes mesures que perseguien en primera instància minorar aquests impactes sobre el medi i les persones; és aquí quan s’abandona la gestió “incontrolada” per passar a la gestió “controlada” dels residus.

Ara, però, estem immersos en un nou punt d’inflexió: els residus ja no són un element molest del què cal desfer-se: són un recurs i una oportunitat de generar activitat econòmica i llocs de treball.

Ja no és realista pensar en escenaris infinits de primeres matèries. Tenim la certesa que, cada vegada amb més evidència, els recursos naturals entraran en escenaris d’escassetat creixent i els residus, si no són malbaratats, poden esdevenir una font important d’obtenció de nous recursos.

Els residus generats per les activitats s'han de gestionar per minimitzar els impactes negatius sobre el medi ambient i la salut humana. Així, a més de prevenir els efectes més nocius i indesitjables, des del punt de vista del medi ambient, també s'ha de promoure el seu valor com a recurs per a la producció de materials que es poden integrar de nou en els processos de producció, per tal d'avançar efectivament cap a un economia circular. Hem d’entendre, per tant, la gestió dels residus en tant que sector econòmic i potencial generador d’oportunitats, de negoci i laborals.

A Catalunya gaudim d’una trajectòria extensa en gestió de les deixalles. El 1993 va néixer la primera llei reguladora de residus, que ens va situar a tots sobre unes bases modernes i eficaces en la seva gestió, i on va començar el que podríem dir-ne la planificació moderna. Transcorreguts aquests 20 anys, ara hem d’entrar en una etapa nova, en la que el context econòmic dels darrers anys ens ha fet també pensar en com hem d’avançar amb més eficàcia, però també amb optimització econòmica. Cal pensar que l’escenari infinit de primeres matèries ja no és aquest, cada vegada els recursos entraran en escenaris d’escassetat, i els residus poden ser una font contributiva en aquest escenari.

Probabilistic seismic hazard and risk assessment in Spain

Alex Barbat — Tue, 24 Apr 2018 12:25:03 +0200

This monograph explains how probabilistic seismic risk assessments can be performed at different resolution levels using the same methodology, providing results in terms of the same metrics; but it also highlights what the differences in terms of inputs for the analysis are in the different cases. A country level assessment is first performed using a coarsegrain exposure database that includes only the building stock in the urban regions of Spain. A detailed urban seismic risk assessment is performed for Lorca, Murcia, Spain. In both cases, the fully probabilistic seismic risk results are expressed in terms of the loss exceedance curve, which is the main output, from where different probabilistic risk metrics, such as the average annual loss and the probable maximum loss can be derived. Because of the damage data availability for the Lorca, May 2011, earthquake, a comparison between the observed losses and those modelled using an earthquake scenario with similar characteristics in terms of location, magnitude and spectral accelerations was done for the building stock of the city. The results of the comparison are presented in terms of expected losses (in monetary terms) and damage levels related to the obtained mean damage ratios are compared with those observed by post-earthquake surveys. This monograph is an effort to explain, in a transparent and comprehensive way, through a step by step example, how risk can be calculated in probabilistic terms and what are the influences of the inputs in each of the stages and what the obtained results mean. After reviewing several available tools to estimate catastrophe risk by means of probabilistic approaches, the CAPRA Platform was chosen because its flexibility, compatibility with the assessments to be performed at different resolution levels and its open-source/freeware characteristics.

Earthquake resistant design of framed structures

Alex Barbat — Tue, 24 Apr 2018 08:18:33 +0200

The monograph begins with a review of the usual seismic analysis procedures and presents the problem of seismic-resistant projects. The required structurual analyses can be elastic or inelastic, but the latter have been used mostly during the last decade thanks to advances in numerical methods and in the area of computers. It also presents a summary of the most common seismic codes prescriptions for reinforced concrete elements and examines aspects of conceptual design that often come from code recommendations. Next, an introduction to the theme of performance based design is made. A method for linear seismic dimensioning is then developed, but with displacement amplification factors obtained from research performed on the nonlinear behavior of the structures. This method allows the displacements, and not the strength, to govern the project, is simple to apply, compatible with most of the rules required by the earthquake resistant structures and is illustrated by the application to a group of reinforced concrete framed buildings. Once the buildings designed, they be subjected to seismic actions of the pseudostatic or dynamic type and will undergo a non-linear behaviour. The response of the structures is evaluated by applying a set of limit states formulated in accordance with the principles of performance based design. The non-linear response allows to calibrate some of the factors applied in the seismic project, such as the global ductility, the behavior factor and the redundancy factor and resistance reserve. From the non-linear response, damage indices are obtained, both local and global, that allow the rapid evaluation of the seismic behavior, as well as the identification of the areas in which the damage is concentrated and which must be reinforced. Finally, using a series of thresholds that allow the definition of the limit states, a mixed procedure (deterministic-probabilistic) is applied by means of which the exceedance probabilities of the mentioned states are calculated. These procedure allows calculating fragility curves and damage probability matrices that applied according to the conceptual framework of the performance based design, allow obtaining earthquake resistant buildings.

The fiscal risk management from the perspective of disasters

Alex Barbat — Mon, 23 Apr 2018 16:43:46 +0200

This monograph presents a summary of the importance for the State of having a public policy of protection or financial management of risk from the perspective of disasters. Reference is made to the legal and fiscal responsibility, to the obligations and contingent liabilities that represent, implicitly, disasters for the State. And, also, reference is made to the implications of not having a well-defined “ex ante” policy from the financial point of view for a country prone to disasters of different kinds and, in general, against catastrophic risk. A succint description of the Disaster Deficit Index, IDD, is then made, whuch provides macroeconomic and financial authorities with access, in appropriate terms, to relevant information on disaster risk at the national or subnational level. This indicator allows to dimension the fiscal exposure and the potential deficit - which are contingent liabilities - of the country in a simple way and to identify and propose possible policies and effective actions of financial protection of the State. Likewise, it shows the impact caused by recurrent minor disasters that cause a significant social and environmental risk in the countries. Finally, the basic concepts about the traditional role of the insurance and reinsurance industry and other financial schemes used or that could be explored to integrate them into the integral risk management are presented.

Ineslatic analysis of geometrically exact rods

Alex Barbat — Mon, 23 Apr 2018 16:19:26 +0200

In this work, a formulation for rod structures, able to consider coupled geometric and constitutive sources of nonlinearity in both the static and the dynamic range, is developed. It is extended for allowing the inclusion of passive energy dissipating elements as a special rod element and geometric irregularities as a full three-dimensional body connected to the framed structure by means of a two-scale model. The proposed formulation is based on the Reissner-Simo geometrically exact formulation for rods considering an initially curved reference configuration and extended to include arbitrary distribution of composite materials in the cross sections. Each material point of the cross section is assumed to be composed of several simple materials with their own thermodynamically consistent constitutive laws. The simple mixing rule is used for treating the resulting composite. Cross sections are meshed into a grid of quadrilaterals, each of them corresponding to a fiber directed along the axis of the beam. A mesh independent response is obtained by means of the regularization of the energy dissipated at constitutive level considering the characteristic length of the mesh and the fracture energy of the materials. Local and global damage indices have been developed based on the ratio between the visco-elastic and nonlinear stresses. The consistent linearization of the weak form of the momentum balance equations is performed considering the effects of rate dependent inelasticity. Due to the fact that the deformation map belongs to a nonlinear manifold, an appropriated version of Newmark's scheme and of the iterative updating procedure of the involved variables is developed. The space discretization of the linearized problem is performed using the standard Galerkin finite element approach. A Newton-Raphson type of iterative scheme is used for the step-by-step solution of the discrete problem. A specific element for energy dissipating devices is developed, based on the rod model but releasing the rotational degrees of freedom. Appropriated constitutive relations are given for a wide variety of possible dissipative mechanisms. Several numerical examples have been included for the validation of the proposed formulation. The examples include elastic and inelastic finite deformation response of framed structures with initially straight and curved beams. Comparisons with existing literature is performed for the case of plasticity and new results are presented for degrading and composite materials. Those examples show how the present formulation is able to capture different complex mechanical phenomena such as the uncoupling of the dynamic response from resonance due to inelastic incursions and suppression of the high frequency content. The study of realistic flexible pre-cast and cast in place reinforced concrete framed structures subjected to static and dynamic actions is also carried out. Detailed studies regarding to the evolution of local damage indices, energy dissipation and ductility demands are presented. The studies include the seismic response of concrete structures with energy dissipating devices. Advantages of the use of passive control are verified.

Tools necessary for the seismic evaluation of buildings

Alex Barbat — Mon, 23 Apr 2018 12:25:43 +0200

This monograph presents the fundamental concepts related to seismic action, the structural response of buildings, the assessment of vulnerability, risk and seismic damage. Some indices proposed by different researchers are also indicated to assess the level of damage suffered by buildings under seismic actions. It also describes the ways to define the seismic action that are appropriate to the structural analysis. Techniques are developed to generate artificial accelerograms, which are necessary to perform the evaluation of the non-linear seismic response through an analysis in time. This evaluation also allows obtaining the level of damage suffered by the structures. The seismic action is focused on the city of Barcelona, Spain, which is located in an area of moderate seismicity and, in addition, does not have seismic records. The seismic action is established by seismic design spectra and artificial accelerograms compatible with said spectra. At the end of this work, the responses spectra considered to define the seismic demand and the artificial accelerograms obtained are shown, which can be used for the evaluation of structures for different seismic intensities and for different locations in Barcelona. Finally, a methodology for assessing the vulnerability and the seismic risk of buildings is described. The methodology is applied in several steps and includes modeling and non-linear analysis of structures. It is focused on obtaining fragility curves, which can be generated both through an empirical evaluation and through an analytical evaluation. The first is based on the damage observed in the buildings of an area after an earthquake occurs, while the second is based on a numerical analysis, where the seismic response of the structure is predicted.

Earthquake resistant analysis of buildings. Application of the design code NCSE-02

Alex Barbat — Mon, 23 Apr 2018 09:11:21 +0200

The monograph highlights the way in which, in the long term, the application of design standards can lead to a reduction of seismic risk in urban areas. The seismic design standards make recommendations regarding the seismic loads to be used, the simplified methods of structural analysis, the criteria that must be applied to ensure a good overall behavior of the same, as well as the design details that must be incorporated. The structural analysis procedures foreseen in all the world standards are based on concepts generally used in the static and dynamic calculation of structures. However, the concepts considered when using these simplified procedures of dynamic analysis and the approximate formulas for the determination of the dynamic characteristics of buildings, are not explained. For this reason, the monograph analyzes the content of the seismic-resistant design regulations in relation to the analysis methods they propose, explaining the concepts of structural analysis that are applied in each case, with special reference to the Spanish regulations in vigor, NCSE-02. Since many design codes include rules that are not justified in the text of the regulations, this monograph also deals with aspects of the so-called conceptual design that requires decisive decisions in the initial phases of the design of structures, which condition the seismic behavior of the same. To facilitate the application of the dynamic analysis of buildings, a program developed in Matlab ® has been incorporated, which can be obtained from the web page www.cimne.com/is-56/modal, together with the data files and results, which are described in the Annex to this monograph.

"Ex-post" evaluation of the damage state of buildings affected by an earthquake

Alex Barbat — Sun, 22 Apr 2018 17:08:47 +0200

Once an earthquake has occurred, the inspection of the buildings should be carried out as quickly as possible, in order to reduce the risk and discomfort of the people. This means that it is not possible to perform a detailed evaluation, making a complete geometric survey of the building, taking samples for a detailed analysis of the seismic pathology and performing a numerical analysis using computers. On the contrary, damage assessments and the habitability of buildings should be carried out based on visual inspection and expert judgment. This monograph aims to develop a general methodology for the inspection and classification of buildings affected by an earthquake. It starts by collecting and analyzing the information existing in different countries on the main methodologies of damage assessment and habitability, in order to compare different approaches and identify the necessary bases to propose a methodology for the evaluation of buildings affected by earthquakes. Then, it establishes the procedure to be used to assess the damage and the safety of the buildings after an earthquake. Finally, it proposes a form, of quick and easy application, for the inspection and classification of buildings affected by an earthquake, according to their state of damage and their level of security.

System of indicators for risk evaluation

Alex Barbat — Sun, 22 Apr 2018 13:34:09 +0200

The system of indicators described in this monograph has been the main objective of the operation ATN / JF-7907-RG of the IDB, coordinated by the Instituto de Environmental Studies, IDEA, of the Universidad Nacional de Colombia, sede Manizales, within the regional program on "Information and Risk Indicators and Risk Management" for the Americas, promoted by the IDB, ECLAC and the IDEA between March 2003 and May 2005. The purpose of the indicator system described herein is to assess vulnerability and risk, using relative indicators, to facilitate the decision makers of each country, region or city to have access to relevant information that allows them to identify and propose effective risk management actions, considering economic, social, institutional and technical aspects. This system of indicators makes possible the description of risk and risk management at the national, subnational and urban levels, facilitating the identification of the essential aspects that characterize it from an economic and social perspective, as well as comparing these aspects or the risks themselves among different countries or territorial units. The proposed indicators have been designed for measuring and monitoring purposes over time and for the identification of conditions of insecurity and their causes, using criteria related to the degrees of threat to which the territorial units are exposed and their socio-economic circumstances that influence their vulnerability. The system of indicators described here is framed within a holistic evaluation approach, which, due to its flexibility and possible compatibility with other specific evaluation approaches, will be increasingly used and accepted as one of the best options for the representation of risk and of its management, due to its complex and imprecise nature. Its strength lies in the possibility of disaggregating the results and identifying the factors towards which risk management actions should be oriented, in order to assess their effectiveness. Its main objective is to stimulate decision-making and not the precise evaluation of the risk that is commonly supported in the concept of physical truth.

Methodology for the evaluation of the risk management performance

Alex Barbat — Fri, 20 Apr 2018 17:00:11 +0200

The Risk Management Index, IGR, is an essential technical contribution of operation ATN / JF-7907-RG of the IDB, coordinated by the Institute of Environmental Studies, IDEA, of the Universidad Nacional de Colombia, sede Manizales, within the regional program on "Information and Indicators of Risk and Risk Management" for the Americas, promoted by the IDB, ECLAC and the IDEA between March 2003 and May 2005. It is a composite indicator based on a multi-attribute technique. It represents a series of risk factors that must be minimized through policies and actions to reduce vulnerability and through the maximization of resilience, that is, of the capacity to face and absorb the impacts of dangerous phenomena. Each composite index is made up of various factors that are represented by existing indicators or variables. For purposes of formulating the IGR, it was necessary to propose qualitative indicators, valued with subjective scales, due to the nature of the aspects that are evaluated and due to the lack of pre-existing parameters. The weighting of the indicators that constitute it was made based on the criterion of experts of each country, using numerical techniques consistent from the theoretical and statistical point of view. The IGR is the first systemic approach - based on fuzzy sets - that is used at the international, national and urban levels to assess the performance of risk management, in order to establish targets that improve the management effectiveness. Decision makers, at different territorial levels, now have a useful tool for monitoring the risk management and have the possibility to observe the relative position over time of the studied area and compare the obtained results with other countries, regions or cities. The strength of the IGR lies in the possibility of disaggregating the results and identifying the progress and deficiencies of risk management, with the aim of guiding the actions in order to improve its effectiveness. Its main objective is to stimulate decision-making.

Seismic vulnerability of bridges using simplified models

Alex Barbat — Fri, 20 Apr 2018 16:03:01 +0200

In this monograph, we study the definition of possible damage in bridges by using simplified structural models. The state-of-the-art of the seismic vulnerability of bridges is first discussed and the theoretical background of the methods to evaluate their vulnerability is commented. The existing methodologies to evaluate the vulnerability of bridges are then described in detail; The methods are classified as: (1) methods based on the vulnerability index; (2) methods based on structural analyses; (3) methods based on expert opinion and statistical evaluations; and (4) methods based on statistical evaluations of the observed damages. A simplified methodology to estimate the seismic vulnerability of reinforced concrete bridges with simple pier bent and elastic girders is then proposed. The methodology is applied to an existing bridge, built 30 years ago. The elastic and the non-linear procedures of evaluation are first discussed. The non-linear procedure includes an analytical methodology to estimate the local damage in the piers, using a continuous damage model, and the global damage of the bridge. Thereinafter, a numerical process allows considering artificial seismic actions compatible with the velocity spectrum of deterministic records. Finally, an application of the proposed analytical procedure to estimate the seismic vulnerability of the real bridge is given. The obtained damage results show that the studied bridge would suffer only a minor damage when a seismic action similar to that of the expected seismic scenario is considered. The proposed methodology is compared with previous experimental results and with analytical results obtained by using commercial codes. It is shown that the proposed simplified methodology is less computational time consuming and that it provides reliable values of the maximum damage suffered by the bridge piers.

Vulnerability of motorway bridges. A state of the art

Alex Barbat — Fri, 20 Apr 2018 12:56:18 +0200

In this monograph, a complete review of the state of the art of the seismic vulnerability of motorway bridges is carried out. The work begins with a review of the damage caused by the last major earthquakes in the world. Next, the theoretical framework of the methods of evaluation of the seismic vulnerability of structures is described. Then, different methodologies for the evaluation of the seismic vulnerability of bridges are examined in detail. Advances in assessing their seismic vulnerability should be sought using expert judgment, the study of damage data associated with past earthquakes and the numerical simulation of bridge response. For this reason, in the monograph the seismic vulnerability evaluation methods are classified into the following groups: (1) methods based on vulnerability indexes; (2) methods that use structural analysis; (3) methods based on statistical evaluations and expert opinion; and (4) methods that use the observed damage statistics. Finally, some of the main methods for obtaining the indices that characterize the importance of motorway bridges are described, as well as indices for the evaluation of the liquefaction effect.

Multiphase elastomer numerical model and its application to the analysis of structures with seismic isolation

Alex Barbat — Thu, 19 Apr 2018 17:44:37 +0200

In this monograph, a numerical model based on the finite element method is developed to analyze buildings with base seismic isolation, discretizing the structure-isolator system. In this way, the response of such systems is estimated with greater precision and, thus, the tasks of designing and verifying them is facilitated. The development of the model requires the resolution of the following problems:
• Development of an appropriate constitutive model for elastomers that considers large elastic deformations, incompressibility, visco-elasticity and elasto-plasticity in large strains.
• Incorporation of the constitutive model developed in a general model of dynamic analysis of structures using the finite element method that combines bar elements with plane elements; appropriate constitutive models for the numerical simulation of the structural materials; mixing theory; discretization by layers.
• Application of damage indices that facilitate the evaluation of the global state of the structure after a seismic ground motion.
• Numerical study of the behavior of structures with elastomeric isolation system subjected to earthquakes and their comparison with the corresponding fixed base structures.

Structural analysis concepts in the seismic design codes

Alex Barbat — Thu, 19 Apr 2018 12:00:57 +0200

The standards make recommendations regarding the seismic loads, the simplified methods of structural analysis, the criteria that must be applied to ensure its good global seismic behavior, as well as the earthquake resistant design details that must be applied. The structural analysis procedures included in all the seismic design standards are based on concepts generally used in the static and dynamic analysis of structures. However, when considering the possibility of using simplified procedures of dynamic calculation and of formulas that allow approximating the values of the dynamic characteristics of buildings, the mentioned concepts are not explained in a clear way. For this reason, the present monograph analyzes the content of the earthquake-resistant design codes in relation to the calculation methods they propose, explaining the concepts of structural analysis that are applied in each case, with special reference to Spanish regulations in force, NCSE-02. In addition, this monograph deals with aspects of conceptual design, which provides qualitative descriptions of design solutions based on the designer's experience. In this phase, the structural typology, the plan form of the structure, the distribution of the masses in height and the rigidities are chosen, the organization of the resistant system is specified, etc. It should be mentioned that in many regulations the conceptual design is specified in rules that are not justified in the text. All this implies taking decisive decisions in the initial phases of the design of structures, which condition the seismic behavior of the structures to such an extent that all the subsequent calculations, as well as the design details that are applied, may not have the expected effect.

Metodologia d’anàlisi de l’impacte del TTIP sobre la competència i la competitivitat. Una perspectiva catalana

Joan Ribas — Wed, 18 Apr 2018 16:30:03 +0200

Aquest estudi revisa les metodologies més habituals que s’han aplicat per calcular l’impacte econòmic del Transatlantic Trade and Investment Partnership (TTIP) negociat entre Europa i els Estats Units d’Amèrica. Sobre la base d’aquesta revisió l’estudi realitza una proposta metodològica per analitzar l’impacte del TTIP en l’economia catalana. Les categories d’impacte analitzades, en línia amb l’anàlisi estàndard d’impacte dels tractats comercials, són l’impacte macroeconòmic i l’impacte microeconòmic. Aquests impactes es calculen mitjançat models d’equilibri general, calibrats per capturar els canvis normatius derivats de la integració comercial i mitjançant casos d’estudi que permetin aproximar l’impacte del tractat sobre els sectors més rellevants.

Evaluation of the overall damage index in reinforced concrete framed structures

Alex Barbat — Wed, 18 Apr 2018 15:44:47 +0200

The main objective of this monograph is to evaluate the overall damage index of framed reinforced concrete structures using different models. In order to achieve this objective it is necessary to identify the parameters that most influence the seismic behavior of reinforced concrete buildings and to propose alternatives for the calculation of some of them. In this context, procedures for calculating variables such as the yielding curvature due to inelastic shear are indicated. The methods for assessing the seismic damage in framed reinforced concrete structures are analyzed, and the correlation between the results obtained with different models in several structures with different reinforcement is studied. Based on this analysis, a simplified methodology for evaluating seismic damage using a global (or overall) index is proposed. The seismic action in most damage evaluation methods is defined by means of accelerograms. Very few methods calculate the damage defining the action by means of response spectra. Although there is no theoretical justification for the possibility of using modal analysis in the context of inelastic analysis, in the seismic analysis of structures this type of calculation is included in all seismic design regulations in the world. The proposed calculation method uses response spectra, is easy to use, can be applied to any type of earthquake, determines the zones that are going to enter into the non-linear range, the maximum lateral displacement that is expected and indicates the overall damage index of the structure.

Modeling of seismic hazard

Alex Barbat — Wed, 18 Apr 2018 14:22:48 +0200

The design and construction of structures in seismic areas requires knowledge of the seismic actions to which they can be subjected throughout their useful life. In general, it is not enough to establish what would be the maximum acceleration which could act upon the structure to be designed, but, in addition, the frequency with which the seismic phenomenon occurs and the damage it would produce should be known. In this monograph the probability of occurrence of earthquakes is studied regardless of the type of structure, of the population of the area, of the industrial level of the same, for the northeast area of the Iberian Peninsula; the results obtained are reflected in maps. The study is restricted to finding the probabilities of occurrence of earthquakes classified by their intensity (epicentral or felt) and, in spite of the approximation due to the use of the intensities, the results will be of great value for the making of design decisions. The methods for evaluating these probabilities of intensity occurrence are very varied, but basically there are two different conceptions of the methods of calculation: the deterministic methods and the probabilistic ones. The deterministic methods start from the recorded earthquakes and evaluate the effects of these using different coefficients. The probabilistic methods do not directly use the recorded earthquakes, but these data serve to establish certain laws of probability of occurrence that give rise to regional or zonal models of occurrence. The method presented herein has elements of both approaches, although always in the context of Bayesian statistics and is adapted to the special conditions of the northeast of the Iberian Peninsula or other areas where data are scarce and seismicity is moderate.

Probabilistic evaluation of the seismic vulnerability and risk of reinforced concrete structures by means of simulation

Alex Barbat — Tue, 17 Apr 2018 17:02:14 +0200

The present work is aimed at conducting studies of vulnerability and seismic risk of building structures. The objective of such studies is to try to predict the damage expected in a structure, in a group of structures or in an entire urban area, for an earthquake of certain characteristics. Once the expected damage is known, solutions can be found to reduce the losses that future earthquakes would cause. The wide use that reinforced concrete has had as building material in recent decades requires an in-depth study of the seismic behavior and of the degree of vulnerability of buildings constructed with this material. For this reason, in this monograph a methodology for assessing the vulnerability and seismic risk of said buildings is applied. One of the central aspects studied is related to the use of the probabilistic simulation of the seismic behavior of the structures. The method of the vulnerability index applied to reinforced concrete structures is described, which is used for the large-scale evaluation of the seismic quality of the structures. Then the methodology is applied to the study of the seismic vulnerability of the structures, obtaining as a result vulnerability functions and damage probability matrices. Using these curves, the probabilistic seismic risk study is carried out in the central area of Barcelona, Spain, calculating the annual probable loss rates in the area and analyzing the possible costs of insurance against earthquakes. Some seismic damage scenarios obtained with the help of a geographic information system are also developed. Finally, the results and measures to reduce the risk in the area are analyzed.

Seismic design of reinforced concrete buildings

Alex Barbat — Tue, 17 Apr 2018 10:17:05 +0200

The monograph is subdivided into two parts. The first part presents concepts of seismology such as intensity or magnitude, together with probabilistic concepts related to the vulnerability and the potential damage that can occur in reinforced concrete and masonry buildings. Procedures for the preliminary design of buildings are included together with conceptual design recommendations. A brief introduction to the expert systems is made, presenting the qualitative reasoning systems in more detail and giving examples for the preliminary design of structures. Finally, a summary is made of the equations that govern the dynamics of linear and non-linear structures and their solution, including numerical procedures for the modal uncoupling and the step-by-step integration of the equations of motion. In the second part of the monograph, the non-linear behavior of structures subject to earthquakes is studied. This allows to predict the response of inelastic structures without the need of performing a non-linear analysis. The relative influence of various parameters such as structural damping, global ductility and the coefficient of strength is presented in detail. Next, the seismic action necessary in the analysis of structures is defined by means of accelerograms and seismic response spectra, but the one performed in several design standards of the world is also discussed. Finally, procedures are developed for the seismic design of structural elements and systems such as reinforced concrete ductile frames, dual systems and eccentric frames. The monograph includes a brief synthesis of earthquake-resistant design codes.

Simulation of damage scenarios for seismcic risk studies

Alex Barbat — Mon, 16 Apr 2018 15:48:24 +0200

The present monograph is a continuation of the monograph MIS-10 and uses the same concepts and definitions described therein. However, to facilitate reading, the authors briefly describe some of the aforementioned concepts. The monograph is based on the definition of seismic risk based on the convolution of three factors: 1) the seismic hazard, which represents the probability of occurrence, within a specific period of time and a given area, of a seismic motion with a given intensity; 2) the seismic vulnerability of a structure or group of structures, defined as the degree of damage due to the occurrence of a seismic motion of a given intensity; 3) the cost of the structures. It is explained that the mechanism to reduce seismic risk is the reduction of vulnerability and, therefore, its evaluation is required. The main result of the risk studies is the expected loss (or the expected degree of damage) that a structure of a given typology would suffer due to the action of an earthquake of certain characteristics. This result can be described by means of damage probability matrices, or by vulnerability functions (relations that express, in a continuous way, the vulnerability according to a parameter that describes the size of the earthquake). The calculation, both of probability matrices of damage and of vulnerability functions, can be carried out, on the one hand, from statistical studies of data observed during past earthquakes or, on the other, by calculating the response of structures based on models.

Seismic risk, hazard and vulnerability of masonry buildings

Alex Barbat — Mon, 16 Apr 2018 12:00:41 +0200

This monograph describes a conceptual framework necessary for the formulation of seismic risk and of vulnerability studies. The Italian methodology of the vulnerability index is described for unreinforced masonry buildings and is applied to an area of the downtown of the city of Barcelona, Spain. A Geographical Information System (GIS) is used which allows automating the process completely and facilitates obtaining the results. Studies of observed seismic vulnerability, based on the damage caused by earthquakes in the past, are performed and their relationships with the previous method is examined. An efficient scheme is proposed to carry out post-earthquake investigations which is applied to the case of the two earthquakes that occurred in the region of Almeria in December 1993 and January 1994; it is explained how to make effective use of the results. To achieve this objective, data on the effects of the mentioned earthquakes has been collected and processed with the objective of obtaining the first observed vulnerability function for Spain. This function would allow the evaluation of future losses due to earthquakes in Spain. In this way, both a seismic risk study methodology and a complete procedure to evaluate the seismic vulnerability of an entire area in an urban will be available.

Definition of the seismic action

Alex Barbat — Mon, 16 Apr 2018 10:40:10 +0200

The present monograph describes different ways to define the action of earthquakes upon structures. The progress that has taken place in recent years the application of different models to define the seismic action requires a panoramic view of the different existing methods. However, the literature on such methods is widely dispersed in different publications, and this publication brings together and synthesizes the most outstanding models. The fact that the seismic action has a a complex nature, and that frequently occur seismic events that exceed the forecasts, has maintained the traditional vocation of the Earthquake Engineering to collect and assimilate the new developments in fields as diverse as seismology, signal analysis, probability theory and stochastic processes, mechanics of materials, etc. Important developments have been achieved in the traditional model of response spectra, usual in the everyday design of simple structures, incorporating spectra based on seismological models, of damage indices or of energy. A wide range of algorithms for the simulation of accelerograms are also available, ranging from those that are limited to the compatibility with response spectra or with a seismological model to those that allow developing spatial models of the waves. Finally, an important development has taken place in relation to the stochastic modeling of the seismic action, which has made possible advances in the probabilistic methods of structural response and in the structural safety.

Nonlinear active control of buildings with base isolation

Alex Barbat — Fri, 13 Apr 2018 15:37:16 +0200

In this monograph, we study a type of hybrid system that combines a base isolation system with an active control system that applies forces on the base. The control forces are calculated by means of a control law that guarantees an adequate behavior, both of the structure and of the base, considering a wide class of non-linearities of the base isolator and uncertainties in the dynamic model and in the excitation. In order to simulate properly the proposed hybrid system, algorithms are used able to analyze the effect of the base isolation with non-linear behavior. At the same time, it is necessary to have a control law that generates the active control force, whose objective is examined from the point of view of the behavior of the system composed by the structure and the base isolation in purely passive conditions. The control law is formulated for the two subsystems coupled through their boundary conditions. The active control forces are applied upon one of the subsystems in order to guarantee a form of practical stability. In this case, the subsystem over which the control acts is the base and the other subsystem is the structure. In the monograph the equations that describe the two systems of seismic base isolation considered in this monograph are developed (one hysteretic and the other frictional), the use of the hybrid system is justified, the different components are described and a critical analysis of the different existing hybrid systems is performed. The law of adaptive control is developed, the hypotheses are stated and the stability of said law is analyzed. The developed strategy is applied to different buildings with base isolation systems and numerical simulation results of their seismic response are shown.

Factores de prestaciones sísmicas de edificios con irregularidad en planta

María Jesús Samper — Fri, 13 Apr 2018 15:34:56 +0200

Some residential buildings are irregular, having plants with entrances, fact which can worsen their behavior during potential seismic events. They can present demands that are much higher than their design capacity. The objective of this monograph is to study the seismic performance factors of buildings by applying the FEMA P695 methodology to a set of regular and irregular structural configurations with and without incorporating closure beams in their entrances. The case studies consider low-rise reinforced concrete buildings located in high seismic hazard areas. The structures are analyzed, considering the hypothesis of flexible diaphragm, in the linear range (using the Robot Structural Analysis computer code) and in the nonlinear range (using the SeismoStruct 7.0.3 computer code); both are based on the finite element method. The seismic response of the structures is evaluated by performing nonlinear pseudo-static analysis and incremental dynamic analysis (IDA). It is worth noting that the response of the buildings with entrances by applying the pushover analysis requires specifying certain rules of application, which are proposed herein. The performance point is calculated by applying the extended N2 method, which is especially applicable to buildings with irregularities in plan considering the effect of the higher modes of vibration. This allows obtaining the seismic response of the buildings to earthquakes similar to those of the seismic code. The displacement corresponding to the performance point allows making evaluations by means of the method of the quadrants and the damage index indicates if the structure is fragile or ductile. In addition, an alternative method is proposed to obtain the ductility and factors such as the torsional irregularity index, which is a dimensionless coefficient that characterizes the structural response and relates it to the existing irregularities. Comparisons among structures with different irregularity in plant are also made considering their fragility curves. The R coefficient is adopted according to the current regulations applying FEMA P695 and a new value of R is established by using the IDA curves obtained from the nonlinear analysis.

Seismic vulnerability of buildings

Alex Barbat — Fri, 13 Apr 2018 10:37:29 +0200

The monograph summarizes the problem of risk for any type of natural phenomenon, defines each of the terms that intervene in the risk analysis, describes the way in which these terms interact and some of them are particularized for the case of the seismic phenomenon. A synthesis is made of the deterministic and probabilistic methods for the evaluation of the seismic hazard at regional and local scales. Then, the theoretical basis of the analytical methods for assessing seismic damage in buildings is explained. The hysteretic behavior of reinforced concrete elements is studied, the factors controlling this behavior and the main computational models are described. The different indicators used to estimate the damage in structural elements and globally in the structure are examined and the probabilistic interpretation of the analytical methods is explained. Next, we describe the subjective methods of damage prediction, such as those based on damage probability matrices or vulnerability functions, and we show the form taken by the specific risk equation in each of these two cases. A methodology for the evaluation of seismic vulnerability in urban areas is developed, based on the vulnerability index method; it is described how the vulnerability of a building is calculated and the existing vulnerability functions for the estimation of risk scenarios are shown. The problem of the seismic risk analysis at urban level is studied and an example of application of this methodology to a sector of Barcelona is shown. Finally, a procedure for the simulation of vulnerability functions for reinforced concrete buildings is described and vulnerability functions are obtained for different structural typologies and different degrees of seismic intensity.

Buildings with nonlinear base isolation

Alex Barbat — Thu, 12 Apr 2018 18:48:48 +0200

The objectives of the seismic design of buildings can be achieved by applying techniques of conventional design that consider the that the ground motion is transmitted to the structure through its fixed base. As an alternative to this traditional design, base isolation systems were developed consisting of mechanisms that partially uncouple the structure of the foundation ground to reduce, in this way, the damages of the structure and of its content. Decoupling is carried out by placing support devices between the base of the structure and its foundation that increase the flexibility of the overall structure-base system and that produce, at the same time, an appropriate damping. Despite the large number of studies on different base isolation systems, there are few comparative analyzes between these systems. In this monograph, structures isolated with different systems are compared with structures with conventional design. To this end, criteria for evaluating the behavior of the different systems have been defined. In the numerical studies, models with linear behavior for the structure and nonlinear behavior of the base isolation system have been considered. The type of nonlinearity of the isolation is formulated by means of differential equations, capable of describing both hysteretic and frictional systems.

Simulation of the seismic damage in reinforced concrete buildings

Alex Barbat — Wed, 11 Apr 2018 18:31:28 +0200

There is a general interest in civil engineering to quantify the damage produced in structures by catastrophic actions. It would be convenient, from a practical point of view, to describe the state of a structure by means of a single figure that clarifies whether the structure is capable of supporting the service charges or not; if it will survive to another extraordinary load in the future; how does the present damaged state influence in its future behavior; where the most damaged points are located; what capacity of resistance remains in each point; and, in general, all kind of information that help to make design or repair decisions. The authors have proposed a solution to this problem in the specific case of earthquakes acting upon reinforced concrete building structures. A methodology has been formulated for the definition of an index of damage that can be typified for all the structures belonging to the same class and that allows classifying them according to their seismic vulnerability. In the monograph, simple beam structures are first studied in order to better describe the concepts involved and the parameters that influence the solution to the problem. The developed methodology, which models the structures using the finite element method, is directly and easily extended to shells, plates or 3D solids. The fundamental idea of this work is to apply constitutive equations formulated in 3D at a material point instead of using constitutive laws formulated in generalized forces-displacements such as, for example, bending moment-curvature, shear force-angular distortion, etc. This allows modeling the behavior of composite materials directly since for each component material its own constitutive law is considered. In this way, it is sufficient to have a single 3D constitutive model and a methodology to calculate the components of the stress and strain tensors at any point of the beam section.

Eficiència en la gestió de la despesa pública

Jordi Baños Rovira — Wed, 11 Apr 2018 13:37:02 +0200

La situació de les finances públiques força a cercar una major eficiència en l’ús dels recursos públics per tal de generar els espais fiscals que permetin finançar iniciatives que donin resposta a les creixents necessitats de la ciutadania. Per a l’acompliment d’aquesta fita, la gestió pública compta amb instruments eficaços, com són la pressupostació per resultats, l’avaluació de polítiques públiques, els processos de revisió de la despesa i la comptabilitat analítica. Tot i que aquests instruments, i els corresponents processos d’anàlisi i presa de decisions, s’han anat introduint en els darrers anys dins del sector públic català, la seva implantació encara dista de ser completa i efectiva. Aquest article, dins la perspectiva de la Generalitat de Catalunya, ofereix una sèrie d’orientacions i prospectiva per a la implementació efectiva d’aquests instruments, i el conseqüent assoliment d’una major eficiència en la despesa pública.

Sostres de despesa, una eina per planificar i contribuir a la sostenibilitat de les finances públiques a llarg termini.

Pallarols Llinàs Esther — Wed, 11 Apr 2018 12:56:02 +0200

Els tres grans objectius dels pressupostos públics són: la disciplina fiscal, l’eficiència assignativa i l’eficiència i l’efectivitat de la despesa.

La disciplina fiscal es tradueix en el control del dèficit, del deute i de la despesa agregada, variables que es troben limitades, en la majoria de països del nostre entorn, a través del que s’anomenen regles fiscals i que tenen per objectiu vetllar per l’estabilitat i la sostenibilitat de les finances públiques a llarg termini, mentre que a curt termini permeten actuar als estabilitzadors automàtics dels pressupost, és a dir, permeten al sector públic dur a terme polítiques contracícliques.

L’eficiència assignativa respon a la necessitat de prioritzar la despesa i assignar els recursos en funció de la utilitat marginal social de la mateixa. És a dir, si el sector públic disposa d’un euro addicional per ser assignat, cal que aquest s’assigni on es generarà una utilitat social més gran, és a dir a on incrementi més el benefici per a la societat. També es parla de reassignació d’acord amb les prioritats, reduint o eliminant programes de baixa prioritat cap als d’alta prioritat.

L’expansió estructural de les exportacions de béns a Catalunya des de l’any 2000

Pau Vilalta — Wed, 11 Apr 2018 12:13:28 +0200

Des de l’any 2000, l’expansió del comerç mundial ha estat molt notòria, amb taxes de creixement per damunt del PIB. Les exportacions catalanes de béns, per la seva banda, han assolit també una gran expansió, amb un creixement fins al 2016 del 92,3% en termes corrents. Només s’ha experimentat un retrocés en els fluxos exportadors l’any 2009, corregit amb escreix durant els anys posteriors, fet que ha donat a l’expansió exportadora un caràcter estructural. Les quotes de mercat de les exportacions catalanes a nivell mundial es mantenen al llarg del període 2000-2016 a l’entorn del 0,5%, tot i la irrupció amb força de la Xina i d’altres noves economies industrialitzades al comerç mundial. El comportament de les exportacions catalanes ha estat millor que el de les economies del seu entorn, fet que ha permès també augmentar la quota de mercat dins les exportacions europees. Com assenyala Antràs (2011), el cas espanyol (i per extensió el català) són excepcionals davant l’afebliment de la posició competitiva revelada de les principals economies avançades. Aquesta expansió, sorgida de la reacció pro-activa de l’empresa exportadora catalana en millorar productes i buscar nous mercats, en particular després del col·lapse de 2009, reflecteix sobretot una ampliació del marge intensiu (el valor mitjà exportat per empresa), però també un eixamplament de la base exportadora regular els darrers anys. Reforçar la diversificació i el dinamisme de les exportacions de més valor afegit són estratègies cabdals per al futur de l'economia catalana. Un altre factor que ha reforçat la tendència creixent de les exportacions a partir de 2009 és el procés de devaluació interna que mostren els índexs de competitivitat basats en els costos laborals unitaris.

L’economia catalana abans i desprès de la crisi

Àngela Fernández — Tue, 10 Apr 2018 12:58:58 +0200

L’economia catalana presenta dos models de creixement ben diferenciats entre el període previ i posterior a la crisi. Però malgrat que s’han recuperat els nivells de PIB previs a la crisi, els nivells d’ocupació no ho han fet encara i el PIB per habitant en relació amb la mitjana europea ha perdut posicions. L’economia catalana té un nivell de productivitat aparent del treball i una taxa d’ocupació similar a la mitjana de la zona euro, però els seus recursos disponibles són inferiors, tant per afrontar els reptes econòmics com socials. Tot i això, l’economia presenta bons resultats en creació neta d’ocupació en activitats intensives en coneixement que són l’aposta per continuar millorant els nivell de productivitat i orientar la seva economia en la trajectòria de la nova revolució tecnològica.

L’habitatge, punt de fuita d’eficàcia de l’Estat de Benestar

Jordi Bosch Meda — Sun, 08 Apr 2018 20:12:22 +0200

L’habitatge és un pilar clau de l’Estat de Benestar com ho són també l’educació, les pensions, la sanitat, o els serveis socials. Però la importància de la política d’habitatge no només rau en la necessitat d’assegurar un bé de primera necessitat a tota la població, ni en l’impacte que té en la qualitat de vida i el benestar de les persones, ni en la materialització d’un dret jurídicament reconegut, com succeeix a Catalunya. Existeix una vasta evidència científica sobre com la manca d’un habitatge digne i adequat en termes físics i econòmics incideix negativament en la salut, en el desenvolupament educatiu dels infants i en les necessitats assistencials i de serveis socials dels membres més vulnerables de la llar, fins al punt que, quan els nivells d’exclusió residencials assoleixen cotes elevades, l’eficàcia del conjunt de polítiques socials es veu greument soscavada. Malauradament, a casa nostra, patim de la manca de consciència que l’habitatge és un dels pilars de l’Estat de Benestar, i encara molta gent segueix confiant en què el mercat garantirà la cobertura de necessitats tant quantitatives com d’ajust del cost. Això ens porta a viure els problemes d’habitatge com un mal endèmic, i a enfrontar cada nova circumstància conjuntural amb perplexitat i amb insuficiència de recursos i d’instruments d’intervenció. En aquesta comunicació s’examinaran les múltiples relacions existents entre la política d’habitatge i la resta de serveis troncals de l’Estat del Benestar, tant de forma general com per determinats col·lectius particularment vulnerables com, per exemple, els infants o les persones grans.

Gestió Activa o Passiva?

Daniel Quer — Sun, 08 Apr 2018 15:14:01 +0200

En aquest escrit tractem la qüestió del debat existent entre la conveniència pels inversors de la gestió activa o de la gestió passiva dels seus actius financers, i l’emmarquem dins d’un debat molt més ampli entre la Hipòtesi del Mercat Eficient (EMH) i el “behavioral finance”, molt present a la comunitat econòmica. En detallem els costos de cadascun dels dos tipus de gestió, i els relacionem. Acabem finalment proposant un model de remuneració de la gestió d’inversions que vagi en funció del tipus de gestió, activa, passiva o semi-activa, que la gestora d’inversions faci, per la qual cosa utilitzem el “tracking error”. La finalitat del treball és una millora dels sistemes actuals de retribució de la gestió d’inversions, augmentant-ne l’eficiència en detriment de friccions que actualment existeixin, com pugui ser la gestió passiva a preus d’activa. No es tracta pas de demanar-ne una regulació afegida, sinó la de fomentar l’autoregulació del sector.

Seismic and structural response of a framed four level building with RC and steel structure designed according to current Venezuelan codes

Alex Barbat — Sat, 07 Apr 2018 09:49:02 +0200

This study determines the structural behavior of a four level framed building with composite RC and steel structure designed according Venezuelan seismic codes. The structural system consists of RC frames in the first three levels and steel frames in the fourth. It was performed linear analysis to design all structural elements. Capacity curves and performance points were obtained with pushover
analysis. Results showed greater ductility in the X frames’ direction and greater resistance reserve in the external frames. Performing points showed adequate resistance values but low stiffness in two Y frames’ directions. Seismic action is carried on through synthetic accelerograms defined by the seismic codes used in this study. Dynamic analysis is used to compute parameters of ductility, over
strength and displacements. In one case the collapse Limit State was reached, implying a general collapse of the building. Incremental dynamic analysis was performed to obtain fragility curves and damage probability matrix; a very high probability of significant lateral displacement and damage was evidenced from this despite a normative design of structural elements.

Seismic response and torsional effects of RC structure with irregular plant and variations in diaphragms, designed with Venezuelan codes

Alex Barbat — Sat, 07 Apr 2018 09:39:58 +0200

The objective of this study is to determine the seismic response and torsional effects of an existing Reinforced Concrete building with irregular plant and five levels projected according to an older version of Venezuelan seismic design code. Two structures were analysed: the original building and a redesigned version. Nonlinear static analysis and nonlinear 3D dynamic analysis were applied, based on registers of three synthetic accelerograms compatible with the elastic design spectrum for the used code. In 3D analysis, four structures were simulated, with and without rigid diaphragms so as to compare the seismic behaviour of the buildings. Through this nonlinear analysis parameters were determined that define the behaviour of the structure, torsional moments and rotations in columns reached for simulated buildings. Also, to obtain damage fragility curves for five states damage were generated. Results show that the
original structure has an inadequate resistant behaviour and a high probability of exceeding the moderate damage state, while the redesigned structure presents good performance under seismic events according to the existing code. It was also observed that maximum torsional effects occur in the entrant corners of the irregular plant, which are reduced in mid-rise buildings by using a rigid
diaphragm.

Probabilistic Seismic Damage Assessment of RC Buildings Based on Nonlinear Dynamic Analysis

Alex Barbat — Sat, 07 Apr 2018 09:30:40 +0200

The incremental dynamic analysis is a powerful tool for evaluating the seismic vulnerability and risk of buildings. It allows calculating the global damage of structures for different PGAs and representing this result by means of damage curves. Such curves are used by many methods to obtain seismic risk scenarios at urban level. Even if the use of this method in a probabilistic environment requires a relevant computational effort, it should be the reference method for seismic risk evaluation. In this article we propose to assess the seismic expected damage by using nonlinear dynamic analysis. We will obtain damage curves by means of the incremental dynamic analysis combined with the damage index of Park & Ang. The uncertainties related to the mechanical properties of the materials and the seismic action will be considered. The probabilistic damage curves obtained can be used to calculate not only seismic risk scenarios at urban level, but also to estimate economic losses.

Vulnerability Assessment of Reinforced Concrete Framed Structures Considering the Effect of Structural Characteristics

Alex Barbat — Sat, 07 Apr 2018 09:21:24 +0200

Considering the effects of earthquakes occurred during the last 15 years, this article focusses on finding solutions to minimize the human and economic losses. Several methodologies were developed in order to assess the vulnerability of the built environment with special reference to one of the most suitable structural systems in seismic areas for dwellings, offices or other functionalities, which is the reinforced concrete framed structure. Thus, the present article studies the influence on the vulnerability of reinforced concrete framed structures of geometric structural characteristics like the slab thickness, the building height and the plan configuration. Referring to the slab, it adds supplementary stiffness to the structure that can significantly influence upon its overall failure mechanism. 3D static nonlinear analyses are conducted by means of the SAP2000 computer program. The results are capacity curves which are used to develop the vulnerability curves. Three thicknesses are considered for the slab: 0.1 cm, 0.12 cm and 0.15 m. Medium and high rise structures are considered, with 4, and 8 levels, respectively, in order to determine the influence of the building height on the
vulnerability index. Three plan configurations of the buildings are compared: a square one, a rectangular one and an L shaped one. For all the analyzed cases, the corresponding vulnerability curves are compared. The obtained results reveal that more realistic results for the behavior of the structure can be obtained if special attention is given to the structural characteristics, especially during the conceptual design process.

Probabilistic seismic risk evaluation of reinforced concrete buildings

Alex Barbat — Sat, 07 Apr 2018 09:12:20 +0200

The main objective of this article is to propose a simplified methodology to assess the expected seismic damage in reinforced concrete buildings from a probabilistic point of view by using Monte Carlo simulation. In order to do so, the seismic behaviour of the building was studied by using random capacity obtained by considering the mechanical properties of the materials as random variables. From the capacity curves, the damage states and fragility curves can be obtained, and curves describing the expected seismic damage to the structure as a function of a seismic hazard characteristic can be developed. The latter can be calculated using the capacity spectrum and the demand spectrum according to the methodology proposed by the Risk-UE project. In order to define the seismic demand as a random variable, a set of real accelerograms were obtained from European and Spanish databases in such a way that the mean of their elastic response spectra was similar to an elastic response spectrum selected from Eurocode 8. In order to combine the uncertainties associated with the seismic action and the mechanical properties of materials, two procedures are considered to obtain functions relating the peak ground acceleration to the maximum spectral displacements. The first method is based on a series of non-linear dynamic analyses, while the second is based on the well-known ATC-40 procedure called equal displacement approximation. After applying both procedures, the probability density functions of the maximum displacement at the roof of the building are gathered and compared. The expected structural damage is finally obtained by replacing the spectral displacement calculated using ATC-40
and the incremental dynamic procedure. In the damage functions, the results obtained from incremental static and dynamic analyses are compared and discussed from a probabilistic point of view.

Seismic performance of waffled-slab floor buildings

Alex Barbat — Sat, 07 Apr 2018 09:00:55 +0200

The codes used in seismic design of waffled-slab floors buildings (WSFB), such as the Spanish NCSE-02 earthquake-resistant design code, assign them restricted ductility, utilise linear structural analysis based on modal analysis, but also consider the structural ductility
concept. Uncertainties arise whenever these codes are applied to the special case of buildings with waffled-slab floors, the ductility of which is doubtful. In many cases, during earthquakes, buildings with restricted ductility are unable to reach the ductility values assumed in the design process, although they may exhibit adequate values of overstrength. This paper therefore studies typical WSFB by applying static incremental non-linear analysis procedures (pushover analysis) in order to calculate their actual structural ductility and overstrength values. Fragility curves corresponding to different damage states and damage probability matrices are also calculated and compared with those of moment-resisting frame buildings (MRFB) in order to obtain useful conclusions for earthquake resistant design. One of the most relevant conclusions of this article is that the use of a better confinement and of ductile steel can only improve the seismic behaviour of MRFB but not that of WSFB.

Canvis en la problemàtica de l’habitatge a Catalunya

Daniel Quer — Fri, 06 Apr 2018 19:26:03 +0200

L’any 1988 es va celebrar el II Congrés d’Economia i Empresa de Catalunya impulsat pel Col·legi d’Economistes.

En els 30 anys que ens separen d’aleshores s’han produït canvis substancials en el marc econòmic i legislatiu del país. L’accés a l’allotjament de la població segueix sent avui un tema cabdal a casa nostra, però el vell problema de l’habitatge té avui característiques molt diferents a les que tenia el 1988, qüestió fonamental, sovint oblidada, quan es postulen mesures concretes per contribuir a solucionar els problemes d’allotjament del conjunt de la població i d’aquelles famílies en risc d’exclusió. A diferència d’altres polítiques públiques, per exemple, la d’infraestructures, la política d’habitatge es dona en un context de mercat i la bondat i eficàcia de les mesures dissenyades i implementades dependrà del coneixement que es tingui del funcionament dels mercats i de la seva dependència i interrelació amb l’evolució de l’economia del país.

Avui la nostra societat té un problema d’accés a l’habitatge per una part de la població, igual que 30 anys abans, malgrat que es pot afirmar que en el seu conjunt la població disposa de condicions d’allotjament millors. La crisi econòmica iniciada el 2007 ha reduït la renda familiar de moltes llars i un nombre important de casos d’atur de llarga duració ha portat a una part de les famílies a nivells d’ingressos per sota els mínims de subsistència. La situació d’emergència en matèria d’habitatge ha tingut àmplia repercussió en la percepció pública del problema de pèrdua de l’habitatge, ja sigui en compra o lloguer. No obstant això les estadístiques de desnonament per execucions hipotecàries i per falta de pagament del lloguer no són els indicadors sobre la bondat de les polítiques d’habitatge, però probablement sí de les polítiques del sistema d’assistència social lligat a l’habitatge i al manteniment de nivells mínims de renda familiar.

Probabilistic seismic damage assessment of reinforced concrete buildings considering directionality effects

Alex Barbat — Fri, 06 Apr 2018 15:49:22 +0200

Most of buildings and structures are usually projected according to two main axes. However, the geographical position of these buildings varies randomly. Such random distributions of the azimuthal positions of structures, in most of the cities, generally, are not accounted for when assessing their seismic risk; certainly, the direction of the seismic loads is another highly random variable. Moreover, an additional important source of uncertainty is related to the structural response, mainly due to the random character of the mechanical properties. There is a consensus that uncertainties must be considered for adequately assessing the seismic risk of structures, but these directionality effects have not been deeply explored so far. In this article, the influence of the high uncertainty involved in these input variables on the expected seismic damage is analysed. Thus, an actual earthquake, which affected the southern part of Spain, is studied. Notably, damages on a group of affected buildings, located close to the epicentre, are analysed and discussed in detail. The results show that the influence of the random azimuthal position of structures is an important source of uncertainty and that it should be taken into account when estimating the expected seismic risk in urban areas.

Seismic vulnerability and risk evaluation methods for urban areas. A review with application to a pilot area

Alex Barbat — Fri, 06 Apr 2018 15:40:57 +0200

The most relevant seismic vulnerability and risk analysis methods are discussed and compared in this article using, as a pilot urban area, the city of Barcelona, Spain, where risk studies have been carried out over the last 15 years in the framework of different research projects. Most of the buildings in Barcelona, which have unreinforced masonry structure or reinforced concrete structure with waffled slab floors, show a high degree of vulnerability to earthquakes. The physical seismic risk but also the socio-economic implications of risk are considered in the article. The robustness of the innovative holistic approach, based on indicators related to the physical exposure, the social fragilities and the lack of resilience of urban area, is also proved. Using a geographic information system (GIS), the seismic risk results are described by means of scenarios of expected losses, but also as scenarios of probabilities of occurrence of predefined damage states.

Fourier-based maximum entropy method in stochastic dynamics

Alex Barbat — Fri, 06 Apr 2018 11:50:40 +0200

As the recent research by Trybicki and Sobczyk has demonstrated [1-3] the principle of maximum entropy is a powerful tool for solving stochastic differential equations. In particular, its use in connection with the moment equations generated by the Ito formula provides accurate estimations of the probability density evolution of some oscillators for which conventional methods such as the diverse closure schemes are not applicable. A major computational requirement of the method, however, lies in the need of calculating a large number of multidimensional integrals at each time step -a numerical task for which both accurate and economic algorithms are required. In this paper it is shown that conventional economic integration techniques often lead to numerical collapse of the solution, especially when dealing with higly nonlinear oscillators. A strategy that overcomes this difficulty is proposed. In essence, the integrals are reformulated in terms of multidimensional Fourier transforms, which are solved by an ad hoe FFT algorithm aimed at obtaining only one single "frequency" point. It is demonstrated that the numerical stability and the accuracy of the proposed algorithm are superior to those afforded by other integration schemes.

Improved stochastic linearization method using mixed distributions

Alex Barbat — Fri, 06 Apr 2018 11:36:13 +0200

A new procedure for the random vibration analysis of hysteretic structures using stochastic equivalent linearization is reported. Its aim is to improve the prediction of the response obtained by conventional Gaussian linearization technique. To this purpose, mixed discrete-continuous Gaussian distributions are used taking into account the bounded nature of the non-linear restoring force. The simple but important property of the mixed distribution is its linearity, which allows the use of the previous results obtained by the Gaussian hypothesis, avoiding the need of employing non-Gaussian continuous distributions or other time-consuming techniques such as local Monte Carlo simulations. Closed-form expressions of the new linearization coefficients for the Bouc-Wen-Baber model are then provided. The relative weights of the discrete and Gaussian distributions are calculated in dependence of the degree of non-linearity in each time step. The comparison of the results with previously published ones obtained by simulation shows a good agreement, providing a substantial improvement of the method with respect to the conventional Gaussian technique with the same calculation effort.

Seismic damage evaluation in urban areas using the capacity spectrum method: Application to Barcelona

Alex Barbat — Fri, 06 Apr 2018 10:51:43 +0200

Conceptual aspects related to seismic vulnerability, damage and risk evaluation are discussed first, together with a short review of the
most widely used possibilities for seismic evaluation of structures. The capacity spectrum method and the way of obtaining seismic
damage scenarios for urban areas starting from capacity and fragility curves are then discussed. The determination of capacity curves for buildings using non-linear structural analysis tools is then explained, together with a simplified expeditious procedure allowing the
development of fragility curves. The seismic risk of the buildings of Barcelona, Spain, is analyzed in the paper, based on the application of the capacity spectrum method. The seismic hazard in the area of the city is described by means of the reduced 5% damped elastic response spectrum. The information on the buildings was obtained by collecting, arranging, improving and completing a broad database of the dwellings and current buildings. The buildings existing in Barcelona are mainly of two types: unreinforced masonry structures and reinforced concrete buildings with waffled-slab floors. The ArcView software was used to create a GIS tool for managing the collected information in order to develop seismic risk scenarios. This study shows that the vulnerability of the buildings is significant in Barcelona and, therefore, in spite of the low-to-moderate seismic hazard in the region, the expected seismic risk is considerable.

An Updated Probabilistic Seismic Hazard Assessment for Romania and Comparison with the Approach and Outcomes of the SHARE Project

Alex Barbat — Fri, 06 Apr 2018 08:31:48 +0200

The probabilistic seismic hazard analysis for Romania is revisited within the framework of the BIGSEES national research project (http://infp.infp.ro/bigsees/default.htm) financed by the Romanian Ministry of Education and Scientific Research in the period 2012–2016. The scope of this project is to provide a refined description of the seismic action for Romanian sites according to the requirements of Eurocode 8. To this aim, the seismicity of all the sources influencing the Romanian territory is updated based on new data acquired in recent years. The groundmotion models used in the analysis, as well as their corresponding weights, are selected based on the results from several recent papers also published within the framework of the BIGSEES project. The seismic hazard analysis for Romania performed in this study are based on the traditional Cornell-McGuire approach. Finally, the results are discussed and compared with the values obtained in the recently completed SHARE research project. The BIGSEES and SHARE results are not directly comparable since the considered soil conditions are different—actual soil classes for BIGSEES and rock for SHARE. Nevertheless, the analyses of the seismic hazard results for 200 sites in Romania reveal considerable differences between the seismic hazard levels obtained in the present study and the SHARE results and point out the need for further analyses and thorough discussions related to the two seismic hazard models, especially in the light of a possible future harmonized hazard map for Europe.

Failure pressure evaluation of the containment building of a large dry nuclear power plant

Alex Barbat — Fri, 06 Apr 2018 08:21:04 +0200

The evaluation of the failure pressure of the containment building of a large dry PWR-W three loops nuclear power plant, based on computer numerical simulation, is described in this paper. The proposed method considers fully three-dimensional finite element models in order to take into account the effect of the most significant structural characteristics (presence of three buttresses, penetrations, additional reinforcement around the penetrations, etc.), the lack of symmetry of the forces generated by the prestressing system, as well as the nonlinear behaviour of the materials and the sensitivity of the results to uncertainties associated with several parameters. The computational model is completely described, including the constitutive equations for the concrete, the reinforcing steel and prestressing tendons, the spatial discretization—isoparametric elements including the reinforcement are used. The structural models and the analyses performed for their calibration are also described. The influence on the failure pressure of incorporating the foundation slab in the structural model, and the influence of the thermal effects, are discussed. One of the conclusions of the numerical study is that the failure process can be appropriately simulated by means of a structural model which does not include either the foundation slab or the thermal effects. Finally, results of a probabilistic simulation of the failure pressure are given.

La tercera via: la gestió dels serveis públics bàsics des de l’economia social

Ramon Roig — Thu, 05 Apr 2018 23:33:02 +0200

En la producció i provisió dels serveis públics sempre es planteja el dilema entre 1) gestió directa mitjançant unitats internes de la mateixa administració o empreses públiques, o 2) gestió indirecta a través de fórmules d’externalització dels serveis.

A la realitat hi ha, però, un tercer model, a cavall entre la gestió directa i la gestió indirecta, que passa per la prestació de serveis públics articulats mitjançat empreses de l’economia social. La substitució de l’objectiu de «maximització de beneficis» pel de «priorització de les persones i la finalitat social» transforma i facilita les bases de la relació publicoprivada.

Urban seismic risk index for Medellín, Colombia, based on probabilistic loss and casualties estimations

Alex Barbat — Thu, 05 Apr 2018 17:37:59 +0200

Medellín is the second largest city of Colombia with more than 2 million inhabitants according to the latest census and with more than 240,000 public and private buildings. It is located on an intermediate seismic hazard area according to the seismic zonation of Colombia although no destructive earthquakes have occurred having as a consequence low seismic risk awareness among its inhabitants. Using the results of a fully probabilistic risk assessment of the city with a building by building resolution level and considering the dynamic soil response, average annual losses by sectors as well as casualties and other direct effects are obtained and aggregated at county level. Using the holistic evaluation module of the multi-hazard risk assessment CAPRA platform, EvHo, a comprehensive assessment that considered the social fragility and lack or resilience at county level is performed making use of a set of indicators with the objective of capturing the aggravating conditions of the initial physical impact. The urban seismic risk index,
USRi, is obtained at county level which is useful to communicate risk to decision-makers and stakeholders besides making easy identifying potential zones that can be problematic in terms of several dimensions of the vulnerability. This case study is an example of how a multidisciplinary research on disaster risk reduction helps to show how risk analysis can be of high relevance for decision-making processes in disaster risk management.

Vulnerability index and capacity spectrum based methods for urban seismic risk evaluation. A comparison

Alex Barbat — Thu, 05 Apr 2018 17:27:42 +0200

This article contributes to the development and application of two latestgeneration methods of seismic risk analysis in urban areas. The first method, namely vulnerability index method (VIM), considers five non-null damage states, defines the action in terms of macroseismic intensity and the seismic quality of the building by means of a vulnerability index. The estimated damage degree is measured by semi-empirical functions. The second method, namely capacity spectrum based method (CSBM), considers four no damage states, defines the seismic action in terms of response spectra and the building vulnerability by means of its capacity spectrum. In order to apply both methods to Barcelona (Spain) and compare the results, a deterministic and a probabilistic hazard
scenario with soil effects are used. The deterministic one corresponds to a historic earthquake, while the probabilistic seismic ground motion has a probability of exceedence of 10% in 50 years. Detailed information on the building design has been obtained along
years by collecting, arranging, improving, and completing the database of the dwellings of the city. A Geographic Information System (GIS) has been customized allowing storing, analysing, and displaying this large amount of spatial and tabular data of dwellings. The
obtained results are highly consistent with the historical and modern evolution of the populated area and show the validity and strength of both methods. Although Barcelona has a low to moderate seismic hazard, its expected seismic risk is significant because of the
high vulnerability of its buildings. Cities such as Barcelona, located in a low to moderate seismic hazard region, are usually not aware of the seismic risk. The detailed risk maps obtained offer a great opportunity to guide the decision making in the field of seismic risk
prevention and mitigation in Barcelona, and for emergency planning in the city.

Robustness of the holistic seismic risk evaluation in urban centers using the USRi

Alex Barbat — Thu, 05 Apr 2018 17:18:26 +0200

The Urban Seismic Risk index (USRi) published in a previous article (Carreño et al., Nat Hazards 40:137–172, 2007) is a composite indicator that measures risk from an integrated perspective and guides decision-making for identifying the main interdisciplinary
factors of vulnerability to be reduced or intervened. The first step of the method is the evaluation of the potential physical damage (hard approach) as a result of the convolution of the seismic hazard with the physical vulnerability of buildings and infrastructure.
Subsequently, a set of social context conditions that aggravate the physical effects is also considered (soft approach). According to this procedure, the physical risk index is evaluated for each unit of analysis from existing loss scenarios, whereas the total risk index is obtained by multiplying the former index by an impact factor using an aggravating coefficient, based on variables associated with the socio-economic conditions of each unit of analysis. The USRi has been developed using the underlying holistic and multi-hazard approach of the Urban Risk Index framework proposed for the evaluation of disaster risk in different megacities worldwide. This article presents the sensitivity analysis of the index to different parameters such as input data, weights and transformation functions used for the scaling or normalization of variables. This analysis has been performed using the Monte Carlo simulation to validate the robustness of this composite indicator, understanding as robustness how the cities maintain the ranking as well as predefined risk
level ranges, when compared with the deterministic results of risk. Results are shown for different cities of the world.

Design and implementation of a voluntary collective earthquake insurance policy to cover low-income homeowners in a developing country

Alex Barbat — Thu, 05 Apr 2018 17:11:16 +0200

Understanding and evaluating disaster risk due to natural hazard events such as earthquakes creates powerful incentives for countries to develop planning options and tools to reduce potential damages. The use of models for earthquake risk evaluation allows obtaining outputs such as the loss exceedance curve, the expected annual loss and the probable maximum loss, which are probabilistic metrics useful for risk analyses, for designing strategies for risk reduction and mitigation, for emergency response strategies and for risk financing. This article presents, based on probabilistic risk models, the design and implementation of a risk transfer instrument to cover the private buildings of the city of Manizales, Colombia. This voluntary collective instrument provides financial protection to both, the estate tax payers and the low-income homeowners through a cross-subsidy strategy; besides, it promotes not only the insurance culture but also the solidarity of the community. The city administration and the insurance industry are promoting this program using the mechanism of the property tax payment. This collective insurance helps the government to access key resources for low-income householders recovery and improve disaster risk management at local level.

A disaster risk management performance index

Alex Barbat — Thu, 05 Apr 2018 16:56:52 +0200

The Risk Management Index, RMI, proposed in this paper, brings together a group of indicators that measure risk management performance and effectiveness. These indicators reflect the organizational, development, capacity and institutional actions taken to reduce vulnerability and losses in a given area, to prepare for crisis and to recover efficiently from disasters. This index is designed to
assess risk management performance. It provides a quantitative measure of management based on predefined qualitative targets or benchmarks that risk management efforts should aim to achieve. The design of the RMI involved establishing a scale of achievement levels or determining the distance between current conditions and an objective threshold or conditions in a reference country, sub-national region, or city. The proposed RMI is constructed by quantifying four public policies, each of which is described by six indicators. The mentioned policies include the identification of risk, risk reduction, disaster management, and governance and financial
protection. Risk identification comprises the individual perception, social representation and objective assessment; risk reduction involves the prevention and mitigation; disaster management comprises response and recovery; and, governance and financial protection policy is related to institutionalization and risk transfer. Results at the urban, national and sub-national levels, which illustrate the application of the RMI in those scales, are finally given.

Urban Seismic Risk Evaluation: A Holistic Approach

Alex Barbat — Thu, 05 Apr 2018 16:49:20 +0200

Risk has been defined, for management purposes, as the potential economic, social and environmental consequences of hazardous events that may occur in a specified period of time. However, in the past, the concept of risk has been defined in a fragmentary way in many cases, according to each scientific discipline involved in its appraisal. From the perspective of this article, risk requires a multidisciplinary evaluation that takes into account not only the expected physical damage, the number and type of casualties or economic losses, but also the conditions related to social fragility and lack of resilience conditions, which favour the second order effects (indirect effects) when a hazard event strikes an urban centre. The proposed general method of urban risk evaluation is multi hazard and holistic, that is, an integrated and comprehensive approach to guide decision-making. The evaluation of the potential physical damage (hard approach) as the result of the convolution of hazard and physical vulnerability of buildings and infrastructure is the first step of this method. Subsequently, a set of social context conditions that aggravate the physical effects are also considered (soft approach). In the method here proposed, the holistic risk evaluation is based on urban risk indicators. According to this procedure, a physical risk index is obtained, for each unit of analysis, from existing loss scenarios, whereas the total risk index is obtained by factoring the former index by an impact factor or aggravating coefficient, based on variables associated with the socioeconomic conditions of each unit of analysis. Finally, the proposed method is applied in its single hazard form to the holistic seismic risk evaluation for the cities of Bogota (Colombia) and Barcelona (Spain).

Framing vulnerability, risk and societal responses: the MOVE framework

Alex Barbat — Thu, 05 Apr 2018 16:42:37 +0200

The paper deals with the development of a general as well as integrative and holistic framework to systematize and assess vulnerability, risk and adaptation. The framework is a thinking tool meant as a heuristic that outlines key factors and different dimensions that need to be addressed when assessing vulnerability in the context of natural hazards and climate change. The approach underlines that the key factors of such a common framework are related to the exposure of a society or system to a hazard or stressor, the susceptibility of the system or community exposed, and its resilience and adaptive capacity. Additionally, it underlines the necessity to consider key factors and multiple thematic dimensions when assessing vulnerability in the context of natural and socio-natural hazards. In this regard, it shows key linkages between the different concepts used within the disaster risk management (DRM) and climate change adaptation (CCA) research. Further, it helps to illustrate the strong relationships between different concepts used in DRM and CCA. The framework is also a tool for communicating complexity and stresses the need for societal change in order to reduce risk and to promote adaptation. With regard to this, the policy relevance of the framework and first results of its application are outlined. Overall, the framework presented enhances the discussion on how to frame and link vulnerability, disaster risk, risk management and adaptation concepts.

Methodology and applications for the benefit cost analysis of the seismic risk reduction in building portfolios at broadscale

Alex Barbat — Thu, 05 Apr 2018 16:28:31 +0200

This article presents a methodology for an estimate of the benefit cost ratio of the seismic risk reduction in buildings portfolio at broadscale, for a world region, allowing comparing the results obtained for the countries belonging to that region. This methodology
encompasses (1) the generation of a set of random seismic events and the evaluation of the spectral accelerations at the buildings location; (2) the estimation of the buildings built area, the economic value, as well as the classification in structural typologies; (3) the development of vulnerability curves for each typology; (4) the estimation of the annual average loss of the buildings portfolio in the current conditions as well as in the case of a hypothetical structural intervention. The benefit cost ratio is estimated as the difference between the estimates of the present value of these two annual average losses, divided by the retrofitting costs. This methodology has been applied to the portfolio of public schools of 14 countries ofLatinAmerica and the Caribbean, for evaluating the feasibility of the seismic risk reduction at a national scale.

Hybrid loss exceedance curve (HLEC) for disaster risk assessment

Alex Barbat — Thu, 05 Apr 2018 16:16:21 +0200

Taken into account that the natural hazard risk is a contingent liability and, therefore, a sovereign risk for national governments, it is important to assess properly the potential losses to design a suitable risk reduction, retention and transfer strategy. In this article, a disaster risk assessment methodology is proposed based on two approaches: on the one hand, the empiric estimation of losses, using information available from local disaster databases, allowing estimating losses due to small-scale events and, on the other hand, probabilistic evaluations to estimate losses for greater or even catastrophic events, for which information usually is not available due to the lack of historical data. A ‘‘hybrid’’ loss exceedance curve is thus determined, which combines the results of these two approaches and represents the disaster risk in a proper and complete way. This curve merges two components: the corresponding to small and moderate losses, calculated using an inductive and retrospective analysis, and the corresponding to extreme losses, calculated using a deductive and prospective analysis. Applications of this risk assessment technique are given in this article for eleven countries.

Probabilistic earthquake risk assessment using CAPRA: application to the city of Barcelona, Spain

Alex Barbat — Thu, 05 Apr 2018 15:31:02 +0200

The risk evaluation model CAPRA (Comprehensive Approach to Probabilistic Risk Assessment) is a techno-scientific methodology and information platform, composed of tools for evaluating and communicating risk at various territorial levels. The model allows evaluating losses on exposed elements using probabilistic metrics, such as the loss exceedance curve, the expected annual loss and the probable maximum loss, useful for multi-hazard risk analyses. In this article, the process of probabilistic seismic risk analysis is described, explaining the main features of the CAPRA modules of hazard, vulnerability and risk estimation applied to the city of Barcelona, Spain. In addition, according to the physical risk results and the information on the socioeconomic indicators of the city, this article presents the holistic evaluation of seismic risk, which is a valuable result to facilitate the integrated risk management by the different stakeholders involved in risk reduction decision making.

Deterministic and Probabilistic Earthquake Scenarios for the Seismic Risk Analysis of URM Buildings

Alex Barbat — Thu, 05 Apr 2018 15:08:00 +0200

Barcelona, as well as a large number of cities in the Mediterranean basin, has a housing stock composed of a large number of unreinforced brick masonry buildings. Motivated by different factors, the enlargement of the city (Eixample in Catalan) was held from the second half of the 19th century and the beginning of the 20th, a period in which a large number of buildings of this type were built, many of which are still used as dwellings. Although the buildings were built individually, some of them are linked to adjacent buildings by the side walls. This feature leads to the analysis of the buildings as isolated structures and also as an aggregate. Barcelona is located in a seismic region of low to moderate hazard, with macroseismic intensity between the grades VI and VII of the European macroseismic scale EMS'98. Based on the deterministic and probabilistic response spectra for the different types of soils present in Barcelona obtained in the work of Irizarry (2004), the seismic risk of four individual buildings and an aggregate is evaluated. The buildings are modeled and analyzed using the TREMURI program and MATLAB routines under the guidance of RISK-UE project.

Nonlinear Response of Structures with Sliding Base lsolation

Alex Barbat — Thu, 05 Apr 2018 14:59:18 +0200

It is accepted that sliding or friction base isolation systems effectively protect structures subjected to severe earthquakes. Precise modeling of the sliding connection is, however, still difficult since various parameters influence the friction coefficient. Simplified models, such as those based on a constant friction coefficient, are convenient to understand the behavior of sliding structures and to identify general trends. However, this article shows that for final structural designs (and in particular if the building enters in the nonlinear range) these trends should be used carefully. The purpose oí the article is to discuss the general behavior of structures supported on sliding connections and to describe a simple numeric model to take into account variations in the friction coefficient. The numeric model enables to represent complex force-displacement relationships for the sliding bearings. The model is used to perform a preliminary evaluation of the influence in the response caused by changes in the friction coefficient for elastic and elasto-plastic structures. The variations in the friction coefficient are obtained from experimental testing for a class of teflon-based connections.

Seismic performance of buildings with a class of adaptive nonlinear hybrid systems

Alex Barbat — Thu, 05 Apr 2018 14:50:55 +0200

A class of hybrid control system which combines a passive nonlinear base isolator with an active controller is analyzed. The passive component of the system has a hysteretic behaviour. A single control force is applied on the structural base by means of a new adaptive
control strategy, not requiring knowledge of the system parameters and the excitation and able to handle the typical nonlinearities associated with base isolators. A numerical study is performed to assess the improvement of the behaviour of buildings equipped with this control system.

El sòl per activitats econòmiques: aportacions per a l’increment de la competitivitat del territori i de les empreses

Miquel Morell — Thu, 05 Apr 2018 12:49:02 +0200

El present treball identifica els reptes dels sòls per activitats econòmiques a Catalunya que, a grans trets, poden resumir-se en una realitat actual caracteritzada per l’obsolescència de molts polígons existents, la seva dificultat per la seva posta al dia, la presència de sòls per activitat econòmica en territoris poc competitius en termes territorials i en termes de la racionalitat econòmica, o bé territoris amb dèficits de disponibilitat de parcel·les de superfície que encaixi amb el mercat. Realitat actual que té a veure, entre d’altres factors, amb un procés de producció de sòl basat fins a dia d’avui en una cadena de valor més focalitzada en la producció de nou sòl (creixements en extensió), que no pas en la gestió i/o renovació dels espais en sòl urbà consolidat (processos de regeneració i renovació urbana). El treball apunta línies d’actuació que tinguin per objectiu l’increment de la competitivitat del territori a partir de l’anàlisi de l’oferta de sòl per activitats econòmiques arreu de Catalunya, la cadena de valor de la transformació urbanística del sòl, la legislació urbanística, i la gestió operativa dels sòls d’activitat econòmica. Paraules clau Urbanisme, planejament urbanístic, sòl industrial, regeneració i renovació urbana, Business Improvement Districts

Experiències i limitacions de la gestió del cicle econòmic sense sobirania monetària.

Albert Carreras — Thu, 05 Apr 2018 12:18:01 +0200

Aquestes pàgines són unes primeres reflexions per endreçar l’àmplia problemàtica que suscito. No hi ha ni dades ni resultats, només un esquema interpretatiu.

1. Un cop ens acostem als vint anys de creació del BCE i l’euro, comencem a tenir una experiència prou llarga de gestió d’una economia com la catalana, sense sobirania monetària i en plena globalització. En els primers vint anys, la política econòmica ha estat realitzada en part (principal) per les autoritats espanyoles i en part (secundària) per les autoritats catalanes. Val la pena analitzar els marges d’actuació que ha tingut cada autoritat, especialment la catalana, i com l’una i l’altra han intentat compensar la manca d’instruments monetaris i comercials. Consideraré els resultats, parant atenció als factors externs, als problemes de sintonia o manca de sintonia entre autoritats estatals i autonòmiques i a les polítiques endegades pel govern de la Generalitat. Els xocs positius i negatius viscuts han estat tan grans que convé reflexionar sistemàticament sobre les lliçons que en podem aprendre. Hi havia un curs d’acció alternatiu al que es va prendre? Si existia, era millor que el que es va seguir? Què podria haver canviat d’haver comptat amb més instruments de política econòmica?

2. Quina política econòmica vol i pot fer la Generalitat? No és pas una pregunta simple ni mancada d’importància. Apunta al cor de la capacitat de gestió de les administracions subestatals. En el cas d’una regió de la Unió Europea, particularment de l’Eurozona, apunta a la combinació de manca de sobirania monetària en un espai que no està preparat per a la completa integració monetària, i a la disposició d’alguns poders de promoció econòmica.

La transformació digital a la Indústria. Oportunitats per a les empreses catalanes.

Joan L. Mas-Albaigès — Thu, 05 Apr 2018 11:37:44 +0200

L’adopció massiva de les tecnologies digitals en el món empresarial, industrial, i en general en qualsevol àmbit de l’activitat econòmica està canviant les relacions i les formes de la producció. La transformació digital està propiciant noves oportunitats en forma de nous models de negoci i de penetració a nous mercats i al mateix temps, com tota transformació que mostra símptomes de verdadera revolució, planteja interrogants especialment rellevants en aspectes d’impacte social com per exemple la distribució de la riquesa generada o les futures relacions laborals.

Aquest treball es centra en analitzar la transformació en el món productiu, entès en sentit ampli tant industrial com de serveis, que ja s’està observant, o que es preveu arribi a mig o llarg termini, degut a la introducció de canvis tecnològics de naturalesa digital. De manera particular, es detecten i descriuen quines oportunitats pot representar la transformació digital per a la indústria i les empreses catalanes dels diversos sectors implicats.

L'estudi, doncs, es focalitza en diverses disciplines tecnològiques que tenen una implantació rellevant a Catalunya, tant per la potencialitat en els àmbits de recerca associats com per un teixit empresarial actiu i innovador. En primer lloc s’aborda el cas de la nova economia de les dades, que se sustenta en tecnologies diverses com la computació al núvol, la ciència i analítica de les dades i, sobre tot, la capacitat d’algorítmica avançada. A continuació s’analitza la transformació al voltant de la indústria connectada o indústria 4.0, avaluant les diferents tecnologies que habiliten aquest concepte que, a la vegada, permeten definir la fàbrica del futur. Per a totes aquestes disciplines tecnològiques s’analitza el posicionament de les empreses catalanes i s’identifiquen les oportunitats de mercat que poden representar.

Los determinantes del RevPAR hotelero en Cataluña

Romero Eva — Thu, 05 Apr 2018 11:02:03 +0200

El buen comportamiento del turismo en España y Cataluña se ha traducido en una mejora del ingreso medio diario por habitación disponible (RevPAR) del sector hotelero durante los últimos años. Este estudio busca identificar los principales determinantes detrás del crecimiento del RevPAR en Cataluña y sus factores diferenciales con otras zonas de España bajo un enfoque cuantitativo. Los resultados indican que la evolución del RevPAR durante los últimos años ha venido explicada tanto por factores domésticos como internacionales. No obstante, la importancia de ambos componentes ha sido desigual a lo largo de los años y por zonas geográficas, presentando una importante relación con el peso relativo de las pernoctaciones de turistas domésticos y extranjeros. En adelante, se espera una menor contribución del componente internacional, influido por los efectos del Brexit y la pérdida del turismo prestado.

L’Economia Circular en tant que alternativa al model productiu

Pere Torres — Thu, 05 Apr 2018 11:01:01 +0200

D’un temps ençà, l’economia circular ha guanyat protagonisme mediàtic i discursiu. Tanmateix, molt sovint és presentada com una alternativa més sostenible a la gestió de residus, amb un enfocament que difereix poc del model convencional de les 3 R. En realitat, però, els principis de l’economia circular s’orienten a substituir radicalment les bases que han sustentat el model de producció industrial. La contribució pretén subratllar la necessitat de centrar adequadament els reptes de l’economia circular com un nou mode productiu i aportar criteris sobre els canvis tecnològics, fiscals, legals i corporatius, entre d’altres, que hauria d’impulsar.

Dynamic System Characterization via Eigenvalue Orbits

Alex Barbat — Thu, 05 Apr 2018 10:09:58 +0200

A new model-free approach for the description of general dynamicalsystems with unknownstructure, order, and excitation is introduced. The approach is based on the new concept of eigenvalue orbit. The eigenorbits are obtained by building an associated linear time-variant system through a matrix that relates the output measurements in a moving horizon window and viewing the trajectories of its time-varying eigenvalues. How the eigenorbits may be computed from the measurements and used for the characterization of the original system is shown. The basic properties of the eigenorbits are presented via a series of theorems for the case of a discrete-time, linear timeinvariant
system. A set of examples are included to illustrate these properties for more general classes of systems and to suggest some practical issues that can be drawn from the orbits.

Democràcia i mercats en el temps de la globalització

Antoni Castells — Wed, 04 Apr 2018 17:33:02 +0200

La Gran Recessió ha fet aparèixer alguns dels efectes relativament ocults de la globalització. N’hi ha dos de gran rellevància, que se situen de ple en el terreny de la relació entre política i economia. El primer és el paper relatiu de l’estat i el mercat. En bona part, la crisi ha estat conseqüència del desajustament entre uns mercats globals i uns estats nacionals i caldria examinar fins a quin punt estem entrant en un nou cicle caracteritzat per un major equilibri entre els dos. El segon fa referència al límits de la democràcia en el temps de la globalització. Hem de resignar-nos a haver d’escollir entre un replegament nacional en torn d’unes democràcies amb trets cada cop més autoritaris (‘iliberal democracies’) o bé una globalització presidida per institucions tecnocràtiques sense una base democràtica (‘undemocratic liberalism’)? Aquesta contribució ofereix algunes reflexions sobre aquestes dues qüestions, prestant una especial atenció a la singularitat del projecte europeu.

El mercat laboral català surfejant per les onades de l’automatització digital: una lectura a partir de la crisi i reactivació econòmiques

Josep Lladós-Masllorens — Wed, 04 Apr 2018 17:25:13 +0200

Avenços científics i revolució digital han transformat sensiblement el ritme i abast del canvi tecnològic sense que, més enllà de les oscil·lacions característiques del cicle econòmic, no s’hagi detectat un augment considerable dels nivells agregats de desocupació. Tot i que les noves tecnologies de producció han substituït treball, el seu efecte ha estat més que compensat per mecanismes que directa o indirectament generen una nova o major demanda laboral.

Tot i amb això, la preocupació social sobre les conseqüències del canvi tecnològic es reactiva per una nova onada d’automatizació, basada en la intel·ligència artificial, la robòtica, l’aprenentatge automàtic, la impressió 3D i els algoritmes que milloren la capacitat lògica, de càlcul i de gestió de grans quantitats d’informació.

És ben conegut que les tecnologies digitals tenen la facultat no només de substituir habilitats manuals, també són capaces de reemplaçar algunes habilitats cognitives. L’experiència de canvi tecnològic recent ha evidenciat la seva naturalesa disruptiva no pas al nivell d’ocupació sinó a la seva composició. Les tecnologies digitals manifesten un efecte de biaix, perquè en general es complementen millor amb el treball de major qualificació. Però, a cada lloc de treball, palesen també que, amb independència de les habilitats del treballador, el biaix del canvi tècnic també perjudica a les tasques rutinàries i més repetitives, que són més susceptibles de ser reproduïdes eficientment mitjançant un algoritme.

En aquest context disruptiu, relacionat amb el concepte Revolució 4.0, l’anàlisi dels canvis en la composició del mercat laboral català d’ençà l’esclat de la recent crisi financera, pel que fa a les habilitats disponibles, les característiques dels llocs de treball oferts i les tasques que en ells es desenvolupen, ofereix una aproximació a l’impacte potencial d’aquesta nova fase d’automatització digital, a banda dels aspectes regulatoris i de viabilitat econòmica i tècnica que òbviament se’n derivin.

AIRBNB a Barcelona: formació de preus i distorsions a les plataformes digitals

Josep Lladós-Masllorens — Wed, 04 Apr 2018 17:23:29 +0200

La irrupció de les plataformes digitals, en el marc de l’anomenada economia col·laborativa, ha generat beneficis econòmics evidents relacionats amb la reducció dels costos de transacció, la mobilització de recursos ociosos o l’accés a productes o serveis per part de col·lectius exclosos. Han ajudat a esmenar doncs situacions que els mercats convencionals no resolen adequadament, tant des d’una perspectiva purament econòmica com també des de l’interès social.

L’aparició d’intermediaris digitals que impulsen activitats comercials d’allotjament en xarxa mitjançant models de negoci basats en el P2P, estan esdevenint un dels fenòmens més evidents d’aquesta transformació que pot afectar sensiblement el mercat i les destinacions turístiques.

A partir de la informació proporcionada per la web http://insideairbnb.com/, s’analitza una àmplia mostra d’allotjaments turístics efectuats per particulars a la ciutat de Barcelona, utilitzant la plataforma Airbnb. L’objectiu d’aquesta anàlisi és determinar els principals factors de la formació dels preus, la incidència d’aspectes intangibles com la reputació de l’allotjament o la informació de l’usuari, la irrupció d’operadors corporatius o la transcendència de la localització. Els resultats no confirmen la naturalesa col·laborativa de la plataforma com a simple mercat bilateral ni tampoc les seves virtuts per a un desenvolupament econòmic més equilibrat a la ciutat.

La problemàtica del finançament del transport públic urbà. Sistemes innovadors per cobrir inversions i dèficit d’explotació

Prof. Mateu Turró — Wed, 04 Apr 2018 17:19:01 +0200

La proliferació de l’automòbil que va començar fa una cinquantena d’anys va portar a una reducció de la utilització del transport públic a les ciutats i a l’eliminació de serveis i, en molts casos, d’alguns modes com el tramvia o els troleibusos. Aquests modes es consideraven sorollosos o antiquats i representaven un impediment a una circulació que es volia tan ràpida com fos possible. Es va acceptar, en definitiva, que els cotxes dominessin els carrers i se n’apropiessin també per a l’aparcament. Aquest paradigma de “modernitat” genera unes externalitats que ara tenim ben identificades (contaminació de l’aire, producció de CO2, soroll, accidents i congestió1, a més d’una inacceptable ocupació de l’espai públic). Poc a poc, aquests efectes indesitjats han anat empenyent als responsables de les ciutats dels països més desenvolupats a posar impediments al trànsit i, en paral·lel, per no perjudicar la mobilitat, a recuperar i millorar els serveis col·lectius de transport urbà.

En aquest context sembla evident la necessitat de planejament del sistema de transport urbà i d’una adequada regulació del seu funcionament per evitar que la situació tendeixi al col·lapse i a uns nivells de contaminació insuportables per una societat moderna i desenvolupada. Aquesta intervenció pública ha de perseguir uns objectius d’eficiència global per a la societat que incorpori el pes de les externalitats. Els plans han de ser de qualitat i acceptats pels ciutadans, però és fonamental que es disposi dels mitjans financers per poder-los materialitzar. Cal doncs tenir clar d’on sortiran aquests mitjans per tal de programar amb realisme les mesures que comporten inversió i per assegurar la cobertura dels dèficits d’explotació que genera el transport públic. També cal preveure el paper que han de tenir les diferents administracions públiques en el finançament del sistema.

Desigualdad y redistribución de la renta de los hogares españoles durante la crisis económica, 2007-2015.-

Daniel Quer — Wed, 04 Apr 2018 17:15:02 +0200

Una de las consecuencias económicas más importantes de la Gran Recesión -cuyo comienzo se sitúa en el tercer trimestre del año 2008- ha sido el aumento persistente de la desigualdad de la renta disponible, siendo además los hogares de mayores ingresos los más beneficiados de la incipiente recuperación económica, OCDE (2016). Para el caso español, existe evidencia de que el aumento de la desigualdad de la renta disponible en nuestro país ha sido importante, Goerlich (2016).

Recientemente, el trabajo de Piketty et al. (2018) para la economía estadounidense de Estados Unidos revela un alto grado de desigualdad de la renta desde las últimas décadas del siglo pasado y hasta hoy. Dicho trabajo muestra la distribución personal de la renta nacional, El ejercicio distingue entre la distribución de la renta ‘pre-taxes’ y ‘post-taxes’. Por supuesto esta última es más igualitaria. Aun así, un resultado interesante es que el 10% de la población más rica acaparara el 40% de la renta nacional, mientras que el 50% más pobre sólo mantiene el 20% de dicha renta. Son resultados muy sorprendentes aunque robustos.

La desigualdad económica en España -a nivel de hogar- es relativamente alta, particularmente si nos atenemos a la distribución de la renta primaria, es decir, los ingresos que los individuos obtienen en el mercado por el uso de su fuerza de trabajo y como propietarios del capital. Esto contrasta con una distribución de la renta disponible mucho más igualitaria, como consecuencia del efecto igualador que ejercen las transferencias monetarias públicas a las familias y la imposición personal sobre la renta. La desigualdad de la renta, tal y como tendremos ocasión de comprobar, se caracteriza por una brecha muy significativa entre la renta primaria y la renta disponible de las familias, brecha que además ha ido creciendo durante los últimos años. Dicha brecha es todavía mayor si consideramos la renta extendida de los hogares, donde a la renta disponible le sumamos las transferencias en especie que representan el gasto público en educación y sanidad.

Situació i perspectives de les polítiques de sostenibilitat en la empresa Catalana desenvolupades a través de les agrupacions sectorials (Associacions i Clústers)

Josep Maria Galí Izard — Tue, 03 Apr 2018 17:03:46 +0200

La promoció del desenvolupament d’una economia sostenible, verda o circular és una prioritat per les institucions internacionals i catalanes. La nostra recerca ha consistit en analitzar fins a quin punt les empreses a Catalunya estan adoptant a polítiques de desenvolupament sostenible. L’anàlisi s’ha dut a terme a través de les actuacions impulsades per les institucions sectorials (clústers i associacions sectorials). La conclusió del treball és que les empreses per a les quals les polítiques de sostenibilitat milloren la seva posició competitiva han adoptat progressivament aquestes polítiques. Les raons de no adopció per les que no que no ho fan son que o bé els suposa costos importants que el marc regulatori actual no els obliga a internalitzar o bé perquè el marc legal fa econòmicament inviable la seva activitat. La implantació del marc regulatori recorregut pel Gobierno al TC – amb aixecament recent de la suspensió - ha de ser necessàriament el proper pas de política econòmica que porti al desenvolupament sostenible.

Computer-aided design and analysis of arch dams

Fernando Salazar — Tue, 03 Apr 2018 13:03:01 +0200

Double curvature arch dams feature geometrical complexity with a significant amount of parameters involved. Different criteria exist to assist in the design task, from simplified geometrical approaches to optimization procedures. However, most of them present a lack of flexibility and are not integrated in computer-aided design tools. In this contribution, an interactive and flexible software tool is presented to support the complete design process: geometrical definition, FEM model generation (including the mesh, the loads and the boundary conditions) and thermo-mechanical analysis. The design can be performed with different levels of detail to adapt to the information available in each stage of the project. The tool allows defining the shape of the reference cylinder, the excavation depth and slope along the foundation, the crown cantilever thickness and curvature, the shape and location of horizontal arcs; all these steps were described in former contributions. Here, special attention is paid to the introduction of additional features such as joints, spillways, abutments of varying shape and outlet works. All steps have been defined with a high degree of flexibility in the design process. The tool is integrated with the pre and post process software GiD, which allows taking advantage of its functionalities, such as mesh generation and results analysis. It is also coupled with a specific application for thermo-mechanical analysis of dams, developed in Kratos Multiphysics – a framework for building parallel multi-disciplinary simulation software. The whole design process can be followed in a unique environment, because the structural response of preliminary designs can be computed and the results considered to refine the dam geometry.

A systematic assessment of the influence of geometry and materials properties on the performance of arch dams

Fernando Salazar — Tue, 03 Apr 2018 09:41:01 +0200

Arch dams have different properties that play a relevant role in their behavior, although it is not clear to what degree or in what sense. There is some consensus regarding the relevance of certain factors such as length at crown, height, base and crest thickness, or Young modulus of dam and foundation. However, others such as the shape of arcs and cantilevers, which are correlated and whose effect is more difficult to consider, can also be influential. In this work, a systematic study of the response of arch dams in front of the common loading scenarios has been carried out, taking into account the usual range of variation of their properties. In total, 39 input variables related to geometry, material strength and thermal load were considered. Ranges of variation for each of these parameters have been defined according to the usual design criteria and 3,000 different geometries – together with the corresponding FEM models have been generated with random values of these parameters. The resulting displacements and stresses have been used to fit prediction models based on a machine learning technique named ‘random forests’ that give an estimate of the dam response. The interpretation of these models can be associated with the relative importance of the characteristics of arch dams on each of the behavior variables.

Procedures Based on Composite FEM Technology for the Resolution of Concrete-Framed Structures with Masonry in-fills: Comparison with Mexican Building Code

Alex Barbat — Mon, 02 Apr 2018 20:25:41 +0200

The construction of confined masonry buildings has become a good choice to meet the housing needs of low-income families in
big cities. Despite this, current building codes for such construction allow the use of highly simplified analysis techniques that have hardly changed in the last 40 years. This paper is based on numerical simulation and discusses the need to combine and improve existing techniques in finite-element method (FEM) analysis for composite materials, to assess the overall structural behavior of reinforced concrete structures with masonry in-fills, and consequently to support the derivation of rational rules for analysis and design. Through the use of a simple yet powerful shell finite element (FE), state-of-the-art theories of mixtures to analyze composite materials, a computational tool to generate the volume fraction of composites, and the Mexican building code, this paper attempts to be a guide to numerical reproduction of the overall behavior of confined masonry structures.

Predictive control of structures

Alex Barbat — Mon, 02 Apr 2018 20:10:56 +0200

Different continuous-time approches have been proposed in recent years to formulate active control algorithms to reduce the response of civil engineering structures under dynamic excitations. In this paper, a general formulation of a new discrete-time control methodology is presented and applied to structural control. This methodology, based on the concept of predictive control, is discussed and compared to the optima! control methodology by means of numerical examples.

New Tension-Compression Damage Model for Complex Analysis of Concrete Structures

Alex Barbat — Mon, 02 Apr 2018 20:03:42 +0200

A new damage model, based on continuum damage mechanics and simulating the opening, closing, and reopening of cracks in
concrete using only one surface of discontinuity, is proposed in this article. The model complies with the thermodynamics principles of nonreversible, isothermal, and adiabatic processes. Two scalar internal variables have been defined: a tensile damage variable d+ and a compressive damage variable d−; the threshold of damage is controlled by only one surface of discontinuity and a new parameter controlling the damage variable that should be activated. This new parameter represents the ratio of tensile stress to compressive stress in the damaged material. The continuity of response under complex loads, which is one of the aims of this work, is ensured. An adequate response under different types of loads leads to the conclusion that the proposed model provides a powerful tool to numerically analyze reinforced concrete structures. Validation and illustrative examples are included in the article.

ACTIVE CONTROL OF NONLINEAR BASE-ISOLATED BUILDINGS

Alex Barbat — Mon, 02 Apr 2018 19:56:03 +0200

A hybrid seismic control system for building structures is considered, which combines a class of passive nonlinear base isolator with an active control system. The active control forces are applied to the structural base with the objective of reducing its absolute displacements. An adaptive control law is formulated to compute the control forces to assure a form of stable behavior of the system under seismic excitation and in the presence of uncertainties in the characteristics of the building and the base isolator. Numerical simulations are performed to assess the effectiveness of the hybrid control system. The global behavior of the structurebase-isolator system is such that the absolute base displacement is significantly reduced, the price paid being a slight increase of the response of the structure.