Safety and serviceability of highway bridges, during and after an earthquake, is a prerequisite to ensure continuous transport facilities, emergency and evacuation routes. Recently, fragility curves have emerged as important decision support tools to identify the potential seismic risk and consequences during and after an earthquake. There has been a substantial increase in interest among researchers in the topic of seismic fragility assessment of highway bridges as evidenced by the growing number of published literature. Advanced computational techniques and available resources have led to the development of different methodologies for fragility assessment. This study presents a review of the different methodologies developed for seismic fragility assessment of highway bridges along with their features, limitations and applications. This study presents a review of available methodologies and identifies opportunities for future development. This study mainly focuses on the key features of different method...

Seismic fragility assessment of highway bridges: a state-of-the-art review

Fragility curves for isolated bridges in eastern Canada using experimental results

This Chapter presents a literature review of seismic fragility functions for reinforced concrete road and railway bridges. It first covers the main issues in fragility analysis, such as the systems for classification of bridges, methods for deriving fragility functions, intensity measures, damage states and damage measures. A section is dedicated to the way the uncertainties regarding the seismic action, geometry, material properties and modelling are treated in existing studies. The Chapter deals also with the recent developments that examine special issues which were not addressed in the first generation of fragility curves. They refer to damaged and retrofitted bridges, the effects of corrosion, skew, spatial variability of the seismic action and liquefaction. Finally, a method for fast fragility analysis of regular bridges is presented. The method applies to bridges with continuous deck monolithically connected to the piers or supported on elastomeric bearings and with free or constrained transverse translation at the abutments.

Fragility Functions of Road and Railway Bridges

The seismic damage of various structures has a significant impact on human production and life, to understand the seismic performance of typical structures and analyze their vulnerability characteristics, and achieve the objective of improving the seismic capacity of structures, and data from 18,480 empirical seismic damage samples from 33 cities and towns for the May 12, 2008, Wenchuan earthquake (China) are summarized and statistically analyzed. The reconnaissance results of the empirical seismic damage show that the structures of masonry structure, multistory reinforced concrete structure, bottom frame-seismic wall masonry and brick-timber and brick-masonry building have the characteristics of widespread application, a myriad of samples and typical failure, sample data for the categories of abovementioned structures are analyzed by statistics and numerical methods, and the empirical seismic damage probability matrix models are established. A nonlinear regression model for calculating the vulnerability grade and the number of samples damaged is proposed. Combined with the empirical sample data, the vulnerability regression function and the curve model of multiple structural types in the VI–X region are established. A mean vulnerability seismic index probability matrix model considering the empirical seismic vulnerability probability in the multiseismic region is proposed. The model is validated by using the above sample database, and the mean damage index matrix in the multiseismic zone is obtained. The analysis results can effectively evaluate the vulnerability characteristics of typical structures in multiseismic regions and provide a necessary reference for a view to a future revision of the building codes and seismic intensity scales currently in force.

Analysis of the probability matrix model for the seismic damage vulnerability of empirical structures

Performance evaluation of natural rubber seismic isolators as a retrofit measure for typical multi-span concrete bridges in eastern Canada

This paper illustrates the results of a seismic vulnerability study aimed to derive the fragility curves for typical Algerian reinforced concrete bridge piers using an analytical approach. Fragility curves express the probability of exceeding a certain damage state for a given ground motion intensity (e.g., PGA). In this respect, a set of 41 worldwide accelerometer records from which, 21 Algerian strong motion records are included, have been used in a non-linear dynamic response analyses to assess the damage indices expressed in terms of the bridge displacement ductility, the ultimate ductility, the cyclic loading factor and the cumulative energy ductility. Combining the damage indices defined for 5 damage rank with the ground motion indices, the fragility curves for the bridge piers were derived assuming a lognormal distribution.

Analytical fragility curves for typical Algerian reinforced concrete bridge piers

The main objective of this present work is to estimate the seismic fragility of typical existing buildings in the north part of Algeria, in which we evaluate the performance, the seismic vulnerability and the damage of reinforced concrete frame structures and URM masonry buildings, existing in dominant way in the city of Algiers (Algeria). An analytical procedure for the derivation of fragility curves is proposed. The capacity spectrum method and seismic damage potential for the city, starting from capacity and fragility curves, are then discussed. Different tools regarding the determination of capacity curves of different existing structural systems by using a non-linear structural analysis are implemented and explained. Four damage states are defined for both structural systems. The earthquake action is expressed in terms of spectral values and the seismic quality of the buildings; the probabilities of the damage states are obtained considering a lognormal probability distribution. An ADRS format has been used for the studied area where a significant damage is obtained for mid-rise and high-rise masonry buildings.

Seismic Fragility Evaluation of Existing RC Frame and URM Buildings in Algeria

This study evaluates the seismic vulnerability of an existing URM building which is currently used as a city hall of one of the biggest cities in the east part of Algeria called Constantine. In order to avoid serious damages, in the future, a seismic vulnerability and damage investigation of this kind of buildings are must. A seismic vulnerability study has been considered. Structural analysis is performed based on the site investigation (including inspection of the building and materials characteristics). An analytical procedure for the derivation of fragility curves is proposed. Different tools regarding the determination of capacity curves of the structural system by using a nonlinear analysis are implemented and four damage states are defined. The earthquake action is expressed in terms of spectral values; the probabilities of the damage states are obtained considering a lognormal probability distribution.

Seismic Vulnerability and Damage Assessment of an Existing URM Building

The latest earthquake disasters have highlighted, once again, poor functioning of the existing masonry structures, and the need to intervene all these structures which have been designed with old regulatory criteria, inadequate or those that have been built before the emergence of design codes. The significant progress made in new criteria of earthquake resistant design, should be extended to all the existing structures, it is therefore essential to identify the degree of seismic performance. Unreinforced masonry (URM) buildings represent a significant portion of the residential structures in Algeria, accounting for more than 60% of existing buildings. In addition to significant population, the brittle nature of URM buildings further supports a thorough consideration of seismic response given the susceptibility to severe failure modes. Currently, there is a pressing need for analytically based fragility curves for URM buildings. In order to improve the estimation of damage state probabilities through the development of simulation-based masonry fragilities, an extensive literature survey is conducted on pushover analysis of URM structures. Structural response is evaluated using an advanced capacity spectrum method. Capacity, demand, and response are thus derived analytically and response data is used to generate an improved and uniform set of fragility curves for use in risk assessment. Seismic fragility curves are expressed in multiple forms for wide range of use in loss-assessment applications. Results are discussed and compared with other relationships developed in the literature.

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Analytically Derived Fragility Curves and Damage Assessment of Masonrybuildings

During the last decades, many destructive earthquakes occurred in Algeria, particularly in the northern part of the country (Chlef (1980), Constantine (1985), Tipaza (1989), Mascara (1994), Ain-Benian (1996), Ain Temouchent (1999), Beni Ourtilane (2000), and recently Boumerdes (2003), causing enormous losses in human lives, buildings and equipments. In order to reduce this risk and avoid serious damages to the strategic existing buildings, the authorities of the country, aware of this risk and in order to have the necessary elements that let them to know and estimate the potential losses in advance, with an acceptable error, and to take the necessary countermeasures, decided to invest into seismic upgrade, strengthening and retrofitting of those buildings. To do so, seismic vulnerability study of this category of buildings has been considered. Structural analysis is performed based on the site investigation (inspection of the building, collecting data, materials characteristics, general conditions of the building, etc.), and existing drawings (architectural plans, structural design, etc.). The aim of these seismic vulnerability studies is to develop guidelines and a methodology for rehabilitation of existing buildings.
This paper presents the methodology, based on non linear and seismic analysis of existing buildings, followed in this study and summarizes the vulnerability assessment and strengthening of one of the strategic buildings according to the new Algerian code RPA 99/version 2003. As a direct application of this methodology, both, static equivalent method and non linear dynamic analysis, of composite concrete masonry existing building in the city of "CONSTANTINE", located in the east side of ALGERIA, are presented in this paper.

Fouad Kehila

Papers

Analytical fragility curves for typical Algerian reinforced concrete bridge piers

Seismic Fragility Evaluation of Existing RC Frame and URM Buildings in Algeria

Seismic Vulnerability and Damage Assessment of an Existing URM Building

Analytically Derived Fragility Curves and Damage Assessment of Masonrybuildings

Seismic vulnerability assessment of composite reinforced concrete-masonry building