Scipedia: Alex Barbat's monographs

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.

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.

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.