Proposed Vulnerability Functions to Estimate the Real Damage State of RC Buildings After Major Turkish Earthquakes (original) (raw)
Related papers
Fragility Analysis for Seismic Vulnerability Assessment of Buildings: A Review
Fragility analysis is one of the trending probabilistic seismic performance methodologies. With the advancement in computational methodologies and large database of existing buildings, fragility analysis can be implemented for precise vulnerability assessment of buildings. The vulnerability curves can be categorized into three groups-empirical, analytical and hybrid. Empirical approach includes-Damage Probability Matrices and Vulnerability Functions, which depend on the damage-motion relationship statistics observed after an earthquake. Analytical curves adopt damage distributions simulated from the analyses of structural models. Hybrid curves overcome the deficiencies of the above two approaches by combining post-earthquake damage statistics with simulation techniques. This paper reviews the importance of fragility analysis using existing methodologies and focuses on their key features highlighting limitations. The paper suggests the way forward for selection of appropriate assessm...
Assessment of seismic damage of multistory structures using fragility curves
Performance-based design, PBD, is gaining popularity and its concept hasbeen applied in many international seismic building codes. In this research, five real structures designed according to the Egyptian Building Code, which does not consider PBD, are considered and modeled in a three dimensional way using the software SeismoStruct in order to assess their performance under expected earthquakes. The structures are 2-story, 4-story, 6-story, 8-story and 10-story reinforced concrete framed structures. The structural system of these structures is of the moment-resisting frame type, with and without shear walls. The structures weredesigned under dead, live and seismic forces of " Zone 3 " with a design acceleration of 0.15g.The models were analyzed using incremental dynamic analysis, IDA, considering 12 real records of historical earthquakes. IDA curves were developed for all analyzed models, considering four damage states. Fragility curves were subsequently developed to provide an overview of the expected seismic performance of a typical low or mid-rise multistory reinforced concrete framed structure in Egypt as designed in accordance with thecurrent Egyptian Building Code.
Derivation of Fragility Relations with Regard to Poorly Constructed Existing RC Buildings
2018
The objective of this paper is to illustrate probabilistic fragility assessment of existing residential buildings in Turkey. Poor seismic performance of these buildings during the recent major earthquakes not only exhibit that the present building stock predominantly consists of lowand mid-rise structures with the lack of engineering design and detailing; but also were constructed according to the regulations of the previous versions of seismic codes. The damage in these buildings has accentuated the need for risk assessment of sub-standard structures to estimate the potential damage and to mitigate the losses during future seismic events. Within the scope of this research, an ensemble of 50 existing RC buildings is selected which represent the structural characteristics of existing structures with weakness in stiffness and strength, in addition to poor concrete quality and rebar detailing. The ensemble consists of buildings, which have been site-investigated after the corresponding...
Propagating fragility curve for RC buildings via HAZUS methodology
Materials Today: Proceedings, 2020
In this era where sustainability plays a key role, to design structures for resisting the earthquake in best probable manner is an inspiration for all designers. The recent trend for structural engineers is evolving in the direction of NSA (Nonlinear Static Analysis) in order to generate its ultimate building capacity. Frame structures are evaluated using NSA i.e. pushover analysis to interpret the phenomenon of plastic yielding being experienced within the structure. ATC-40 has well illustrated various performance levels of the buildings. When seismic loads are active due to shaking of ground, it is essential to assess the conditional probability of structural response. This can be done using conditional probability as a function and plotting fragility curves for structural response due to application of seismic activity or loading as a function. These fragility curves are useful not only for calamities before earthquake but also after earthquake to evaluate the seismic losses. The probability of whichever damage state being exceeded can be plotted using fragility curves which can be derived using empirical or analytical methods which rely on both the source of the data along with type of analysis. This paper addresses the analytical method using the guidelines given by the HAZUS MH technical manual. The work represented here is compiled by means of procedure for establishing the fragility curves for three typical Reinforced Concrete (RC) frame structures having variations resembling 3 storey intended for short-period structures, 6 storey used for medium-period structures and 12 storey representing long-period structures. For analyzing structures, FEM based software SAP2000 has been used as a tool. The present study contributes towards quantification of seismic fragility; henceforth fragility curves are co-related and plotted which provides a rational and consistent probabilistic treatment of damage or loss. The fragility curves are figured out to assess and interpret the results.
Rigorous versus less-demanding fragility relations for RC high-rise buildings
Bulletin of Earthquake Engineering, 2020
Analytical seismic scenario-based probabilistic fragility relations form the spine of earthquake risk assessment and mitigation of RC high-rise wall buildings. In this study, a framework is proposed to develop both rigorous (refined) and less-demanding (cheaper) fragility relations for such structures. Multi-record incremental dynamic analysis is employed using a new scalar intensity measure and net inter-storey drift as a consistent global damage measure for varying heights of buildings. To illustrate the framework, a 30-storey wall building located in a multiple-scenario earthquake-prone region is analysed. The refined fragility sets are derived using 40 real earthquake records representing two seismic scenarios, while the proposed methodology to develop less-demanding seismic scenario-based fragility relations employs a considerably lower number of earthquake records. In this methodology, a new record selection criterion and a fragility curve tolerance factor are introduced. Finally, the two fragility relation sets for the reference structure are developed, assessed, and compared to provide insights into their features and accuracy. Using the proposed methodology, the study revealed that fairly reliable seismic scenario-based fragility sets can be developed for RC high-rise buildings with a significant reduction in computational time and efforts. The proposed framework is generic and can be implemented to deriving refined and less-demanding fragility relations for RC high-rise buildings of different configurations and structural systems.
Development of analytical seismic fragility functions for the common buildings in Iran
Bulletin of Earthquake Engineering
One of the main components for the development of regional seismic risk models is the fragility functions for common building types. Due to the differences between the national design codes, construction practices, and construction materials, it is necessary to develop speci c fragility functions for the common building types which are constructed in each region. One of the existing challenges is the lack of classi ed, reliable, and cogent local seismic fragility functions for common buildings in Iran. For this reason, the present study is devoted to lling this essential gap. Therefore, at the rst step, a comprehensive study was performed on the existing building types in the country. Finally, the Iranian common buildings are classi ed into 35 categories regarding material, lateral-loadresisting system, age, height, and code level. Also, by conducting comprehensive studies on all previously performed researches in the country, structural and dynamic parameters have been collected for buildings in each class. This information was used to compute a large set of backbone curves for Iranian buildings taxonomy. In the next steps, a large set of ground motion records were selected. Then non-linear time-history analyses were performed on the generic backbone curve for each type of building, and the structural responses were used to derive fragility functions for building classes. Then nearly three hundred appropriate fragility functions were generated for Iranian common buildings considering both record-to-record and building-to-building response variability using cloud analysis. Based on the existing empirical data from past earthquakes in the country, the validation of the resulting fragility functions was carried out. The resulted fragility functions can be utilized in seismic risk assessment studies in the country.
Simplified seismic vulnerability analysis of historic residential buildings with fragility curves
In the disciplines dealing with the preservation of the built heritage, the assessment of the seismic vulnerability plays a decisive role. A high number of numerical models have been developed to simulate the behaviour of different building typologies subjected to seismic action, but requiring a in-depth knowledge of the object of study they are not suitable for urban scale analysis. The widespread historical built heritage in Italy, as in many other countries, requires the definition of rapid and reliable assessment procedures that allows a large-scale evaluation of the vulnerability of historical buildings before a seismic event. This analysis should be based on existing databases, such as the Reluis-Cartis database, without necessarily proceeding at this stage with detailed investigations of each individual building. Based on state-of-the-art procedures, a methodology is proposed for the fast construction of the fragility curves starting from information available on the Reluis-Cartis database. The curves define the relationship between the probability of reaching a safety factor or a vulnerability index in function of the seismic acceleration PGA. The methodology allows to understand the probability of loss of the structural safety in function of a given PGA. The developed methodology is applied here in two cases: (a) a small historic building hit by several earthquakes in order to calibrate the methodology and (b) to a set of historic building of the same typology in a historic center never hit by earthquakes in order to assess the level of the probability of loss of the structural safety given the code defined PGA, as well as to draw conclusions on prioritizing intervention strategies at the urban scale.
Bulletin of Earthquake Engineering, 2021
This paper describes CEQID, a database of earthquake damage and casualty data assembled since the 1980s based on post-earthquake damage surveys conducted by a range of research groups. Following 2017–2019 updates, the database contains damage data for more than five million individual buildings in over 1000 survey locations following 79 severely damaging earthquakes worldwide. The building damage data for five broadly defined masonry and reinforced concrete building classes has been assembled and a uniform set of six damage levels assigned. Using estimated peak ground acceleration (PGA) for each survey location based on USGS Shakemap data, a set of lognormal fragility curves has been developed to estimate the probability of exceedance of each damage level for each class, and separate fragility curves for each of five geographical regions are presented. A revised set of fragility curves has also been prepared in which the bias in the curve resulting from the uncertainty in the ground...
2009
Earthquake shaking represents complex loading to a structure. It cannot be accurately characterized by a single parameter such as peak ground acceleration. The goal of this work is to compare the role of various strong-motion parameters on the induced damage in the structure using numerical calculations. The most influential parameters are then used to build multi-variable fragility functions, in order to reduce some of the uncertainty inherent in the response to seismic loading. To this end, a robust structural model of an eight-story reinforced concrete building on which dynamic calculations can be performed at an acceptable cost is used. In the model, all elements have a linear behaviour, except the ends of each column and each beam to which a nonlinear behaviour based on damage mechanics and plasticity type (plastic-hinges model) is assigned . Several hundred nonlinear dynamic analyses are carried out on the structure and the damage levels are identified using the inter-story drift ratio, which can be linked to standard damage scales. The spectral displacements, SDs, at the first two modal periods T 1 and T 2 are used to represent the seismic loading as the most useful parameters reflecting the structure´s response [1]. Each pair of points [SD(T 1 ), SD(T 2 )] is associated with a probability of exceeding a given damage level. This probability P is evaluated by considering the damage levels attained by other points located in its neighbourhood. A scalar parameter R = f [SD(T 1 ), SD(T 2 )] is then built up and we can construct an analytic equation for the fragility curve P = g(R) = g(f [SD(T 1 ), SD(T 2 )]). This results in an equation for a fragility surface that offers a more complete and accurate view of the structure´s vulnerability. A comparison between different profiles obtained by the generated fragility surfaces and conventional fragility curves shows the significant role of the second parameter in accurately estimating the probability of damage. Such fragility surfaces can be implemented within earthquake risk evaluation tools and they should provide more precise damage estimations. It is expected that this procedure can lead to more accurate land-planning and retrofitting policies for risk mitigation.
Engineering Structures, 2013
This paper presents a new procedure to derive fragility functions for populations of buildings that relies on the displacement-based earthquake loss assessment (DBELA) methodology. The recent developments in this methodology are also presented herein, such as the development of new formulae for the calculation of the yield period or the consideration of infilled frame structures. In the fragility method proposed herein, thousands of synthetic buildings have been produced considering probabilistic distributions describing the variability in their geometrical and material properties. Then, their nonlinear capacity has been estimated using the DBELA method and their performance against a large set of ground motion records has been calculated. Global limit states are used to estimate the distribution of buildings in each damage state for different levels of ground motion, and a regression algorithm is applied to derive fragility functions for each limit state. The proposed methodology is demonstrated for the case of ductile and non-ductile Turkish reinforced concrete buildings with and without masonry infill walls, and compared with results obtained using nonlinear dynamic procedures and with the results from previous studies.