Abstract

The assessment of damage scenarios and human and material losses is essential for seismic risk reduction, even in regions of low or moderate seismicity. A seismic risk evaluation is carried out in the residential district of Eixample in Valencia (Spain), a district with great historical and architectural value, with predominantly masonry buildings and where most of the modernist heritage of the city is located. Seismic vulnerability has been evaluated following the vulnerability index method [1] obtaining the seismic quality for the residential building stock taking into account the structural typology, maintenance level, age and geometry, and identifying the most vulnerable buildings. Damage probability matrices for deterministic and probabilistic scenarios have subsequently been determined considering a binomial or beta-equivalent probability distribution and, using a geographic information system, scenarios of damage, losses and costs maps have been produced for each earthquake intensity. Results confirm that vulnerability and seismic risk is significant and, therefore, a detailed study will enhance the structural earthquake performance of the buildings in the district, especially if they are protected, helping to reduce human and material losses, and safeguarding the citys heritage. On the other hand, the Special Plan against Earthquake Risk in the Valencia Region, approved in 2011, recommends the development of specific plans in several municipalities including the city of Valencia. This small study can serve as a starting point to be extended to the entire city.

Abstract

The vulnerability index method, in its version developed in the framework of the European project Risk-UE, has been adapted and applied in this article, to evaluate the seismic risk for the city of Barcelona (Spain) through a GIS based tool. According to this method, which defines five damage states, the action is expressed in terms of the macroseismic intensity and the seismic quality of the buildings by means of a vulnerability index. The probabilities of damage states are obtained considering a binomial or beta-equivalent probability distribution. The most relevant seismic risk evaluation results obtained, for current buildings and monuments of Barcelona, are given in the article as scenarios of expected losses.

Abstract

The evaluation of the damage caused by horizontal loads, such as seismic action, to existing bridges has received an important attention
in recent years, because it is the first step towards reducing casualties and economic losses. In damage detection and evaluation, the
application of simple and reliable models has been prioritized, because they are necessary in further multi-analyses required by Monte
Carlo simulations. A simplified moment–curvature damage evaluation model, capable of evaluating the expected seismic behavior of RC
highway bridges is proposed in this paper. The damage of a pier is related to the reduction of the cross-sectional moment of inertia of the
bridge piers. Therefore, the evaluation of the damage is based on a non-linear analysis determining the changes of the mentioned moment of inertia. The model was validated using experimental results obtained at the JRC Ispra for the Warth Bridge of Austria and also FEM analyses performed by other authors for the same bridge.

Abstract

The seismic risk of the buildings of Barcelona, Spain, is analyzed by using a method based on the capacity spectrum. The seismic hazard in the area of the city is described by means of the reduced 5% damped elastic response spectrum. Obtaining fragility curves for the most important building types of an urban center requires an important amount of information about the structures and the use of nonlinear structural analysis tools. The information on the buildings of Barcelona was obtainedby collecting, arranging, improving, and completing the database of the housing and current buildings. The buildings existing in Barcelona are mainly of two types: unreinforced masonry structures and reinforced concrete buildings with waffled slab floors. In addition, the Arc-View software was used to create a GIS tool for managing the collected information to develop seismic risk scenarios. This study shows that the vulnerability of the buildings is significant and therefore, in spite of the medium to low seismic hazard in the area of the city, the expected seismic risk is considerable.

Abstract

Colombian seismic code NSR-98 establishes the requirement for the seismic vulnerability analysis and, if necessary, the strengthening of public facilities (schools). Due to the investments required by risk reduction programs, it is necessary to establish criteria for assigning priorities for the interventions. This article proposes a methodology for obtaining a Benefit-Cost Ratio (BCR) at the
subnational level, by assessing the expected annual average loss of the built area of public schools and the retrofitting cost. The BCR is estimated as the difference between the estimates of the net present value for status quo and retrofitted states, these two divided by the retrofitting costs. According to the BCR, 47.3% of the total school built area of Colombia should be retrofitted where the retrofitting
costs correspond to 25% of the total investment. Proposed BCR is useful for prioritizing regions in function of the feasibility of reducing the seismic vulnerability of the schools.

Abstract

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.

Abstract

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.

Abstract

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.

Abstract

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.

Abstract

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.