Development of earthquake vulnerability functions for tall buildings (original) (raw)
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Effect of earthquake probability level on loss estimations
The ground shaking intensity used for calculating the quasi-static forces to be applied in building design according to the National Building Code of Canada (NBCC) is established by probabilistic seismic hazard analyses. The probability level for which the amplitudes of design motions are determined in the current building code, NBCC-1995, corresponds to a 10% chance of exceedance in 50 years. The insurance industry has funded loss estimation studies at the University of British Columbia for a number of cities in British Columbia, including the largest, Vancouver. This city has the highest seismic hazard among the three most populated urban centres in Canada. A major objective of the studies was to provide a rational basis for discussions with government on how to cope with catastrophic losses in the region. For this reason, it was considered appropriate to use the same probability of exceedance of shaking intensity as that used in NBCC-1995. The seismic provisions of the next edition of the code, NBCC-2005, will be based on a probability level corresponding to a 2% chance of exceedance in 50 years. This paper investigates the impact of this change on the loss estimations for Vancouver. The concepts and strategies used in the Vancouver study are of wide applicability and should be of interest to others engaged in risk assessment.
Controlling Parameters in the Assessment of the Seismic Vulnerability of Buildings
2016
The probabilistic seismic risk assessment in terms of economic losses for building portfolios requires the seismic hazard assessment, the definition and characterization of the building portfolio and the estimation of the expected economic losses of specific building typologies for increasing seismic intensities. The probability distribution function of economic losses for different seismic intensities can be estimated by integration of individual building component ́s repair costs. By means of Monte Carlo simulations, all relevant variables that influences the final repair cost can be introduced into the analysis. The results of the analysis are integrated and represented through specific vulnerability functions for each building typology, which relates the expected economic losses and its corresponding uncertainty measure with the seismic intensity level. The integration of losses considers the uncertainties associated with the hazard assessment, the dynamic response of the model,...
Tall building analytical seismic vulnerability functions for the global earthquake model
Safety, Reliability, Risk and Life-Cycle Performance of Structures and Infrastructures, 2014
Guidelines for developing analytical seismic vulnerability functions are proposed for use within the framework of the Global Earthquake Model (GEM). Emphasis is on high-rise buildings and cases where the analyst has the skills and time to perform nonlinear dynamic analysis. The basis for this effort is formed by the key components of the state-of-art PEER/ATC-58 methodology for loss assessment. Simplified modeling options are proposed to reduce model complexity and ease application for building ensembles. Nonlinear dynamic analysis is employed for the estimation of local story drift and absolute acceleration response to evaluate both structural and non-structural losses. Important sources of uncertainty are identified and propagated using simplified methods based on moment-matching to reduce the computational load. The resulting guidelines allow the generation of vulnerability functions for a class of high-rise buildings with a reasonable amount of effort by an informed engineer.
Probabilistic seismic vulnerability assessment of buildings in terms of economic losses
Engineering Structures, 2017
The probabilistic seismic risk assessment in terms of economic losses for building portfolios aims to the estimation of the probability distribution functions (PDF) of economic losses for a set of stochastic events representing the seismic hazard at a particular geographic zone. This paper proposes a methodological approach to evaluate and integrate, in a consistent and rigorous way, the economic losses as a function of the seismic hazard intensity for prototype building constructions. Prototype building models are designed and characterized with a set of reference parameters. By means of 3D structural models, detailed nonlinear response history analyses are performed for a set of seismic records at several increasing intensities. Seismic records are selected to represent particular seismological and geotechnical conditions at the site of analysis. Then, a component-based model is conformed considering structural, non-structural, and content components potentially susceptible to damage. Each component type is assigned a fragility specification for various damage states in terms of costs and times of repair. Using Monte Carlo simulations, the different sources of uncertainty are included in the assessment of the costs and times of repair at different seismic intensities. Uncertainties in the hazard, model response, damage states, and costs and times of repair are considered. Aspects such as geographical variations in the hazard, scale economy, special commercial conditions, minimum or total intervention costs, and business interruption costs are included in the assessment. Finally, the results are represented by means of vulnerability functions for specific building typologies. To illustrate the methodology, a case study is presented in detail for a typical 5-story reinforced concrete moment resisting frame building designed for special seismic code level and located in a typical soft soil deposit of Bogotá, Colombia. Additional results are presented for six (6) different building typologies illustrating variations in results due to different story heights and seismic code levels. The resulting vulnerability functions are compared with equivalent results from other similar methodologies. Conclusions and possible potential applications related to probabilistic risk assessment are summarized.
E3S Web of Conferences
Earthquake loss estimation (ELE) refers to the analysis and study of the possible effects of an earthquake in a region or population and quantifies the consequences of the earthquake. The objective of this study is to provide an insight into earthquake loss estimation for the most common approaches by seeking to survey the current methodologies for quantifying the earthquakes' negative effects. Naturally, peoples search about desirable approaches to estimate of earthquakes costs and losses which are not predetermined to subsist as usual. Other issues related to those approaches are endeavor to achieve the state of art to quantify the earthquakes consequences, the aspects of a building's response to earthquake. The aspects that will be characterized in this research are: 1) Input data like building information (Structure system, location, occupation, etc.), earthquake hazard; 2) Analysis methods; 3) Output data. ELE methods are categorized in different ways depending on one o...
Comparative earthquake loss estimations for high-code buildings in Istanbul
Soil Dynamics and Earthquake Engineering, 2020
The paper presents the probabilistic and scenario based earthquake loss estimations for the case that the hazard and building inventory inputs are kept the same whereas the damage functions as well as the seismic demand estimation method are changed in an earthquake loss model. Spectral acceleration-displacement based damage assessments by alternating damage functions and inelastic demand evaluation methods are performed for high-code buildings in Istanbul. The buildings are mid-and high-rise, reinforced concrete, moment-resisting frames that are assumed to be designed in accordance with the provisions of Turkish Earthquake Resistant Design Code (1998). Three damage models, i.e. structural capacity and fragility curves, are employed for each building class: Expert judgment based capacity and fragility functions; HAZUS's high-code seismic design level capacity and fragility functions; and Capacity and fragility functions derived based on nonlinear analyses of code complying RC frames. Inelastic spectral displacement demands are computed with three methods: Capacity Spectrum Method, Modified Acceleration-Displacement Response Spectrum Method, and Displacement Coefficient Method. Analyses are realized under site-specific ground motions based on a state-of-the-art hazard model for eight return periods ranging from 100 to 2475 years as well as for an Mw ¼ 7.5 scenario earthquake. Probabilistic loss curves for each case are developed. Estimated average annual losses (AAL) and loss ratios (AALR) are compared. Grid and district based maps illustrating the spatial distributions of estimated long term average losses per year and the loss ratios are presented. The estimated annualized loss ratios at district level in the city are compared to the earthquake insurance premium rates.
Earthquake vulnerability assessment of buildings for catastrophic risk analysis in urban areas
A catastrophic risk model has been developed to evaluate, building by building, the probabilistic losses and pure premiums of different portfolios. The model includes a hazard module, an exposure module, a vulnerability module and a risk module. A brief summary of the methodological approach adopted for catastrophic risk assessment and an improvement methodological approach for the vulnerability assessment of building structures is presented. Dynamic nonlinear or simplified nonlinear analysis, the consideration of multiple damage functions for different types of components of the construction and a repair cost methodological approach are proposed in order to integrate the total economic losses for the building, for different performance levels of analysis. The methodology is illustrated with a one-story, one-bay reinforced concrete moment resisting frame with unreinforced masonry infill walls. Preliminary conclusions and recommendations are presented for the implementation of the proposed methodology.
Simplified Estimation of Economic Seismic Risk for Buildings
Earthquake Spectra, 2004
A seismic risk assessment is often performed on behalf of a buyer of commercial buildings in seismically active regions. One outcome of the assessment is that a probable maximum loss ( PML) is computed. PML is of limited use to real-estate investors as it has no place in a standard financial analysis and reflects too long a planning period. We introduce an alternative to PML called probable frequent loss ( PFL), defined as the mean loss resulting from shaking with 10% exceedance probability in 5 years. PFL is approximately related to expected annualized loss ( EAL) through a site economic hazard coefficient (H) introduced here. PFL and EAL offer three advantages over PML: (1) meaningful planning period; (2) applicability in financial analysis (making seismic risk a potential market force); and (3) can be estimated using a single linear structural analysis, via a simplified method called linear assembly-based vulnerability (LABV) that is presented in this work. We also present a simp...
Bulletin of Earthquake Engineering, 2021
This paper focuses on the exposure and fragility/vulnerability of the residential, mixed residential/commercial, and public building stock of the city of Isfahan, in Central Iran, and constitutes the first part of a seismic risk assessment study for that city. To determine the assets at risk, we first summarize the details of the building stock and population from the available georeferenced 2011 Census data. From this dataset and from a local survey of the city, we categorize the building taxonomy in 27 construction classes characterized by age, height, and material/lateral-load-resisting system. A building exposure model is then assembled by first dividing Isfahan in city blocks and then by assigning the appropriate statistical properties to the buildings, such as construction class, built area, and replacement cost. The population of each city block is also estimated and accounted for. To assess the fragility and vulnerability to earthquake ground motion, for each building class we performed nonlinear dynamic analysis of multiple equivalent single-degree-of-freedom systems. This process generated a set of classand region-specific fragility and vulnerability functions that considered both record-to-record and building-to-building response variability. In the companion paper we used the exposure model and the fragility and vulnerability curves generated for all these asset classes to probabilistically assess the seismic risk of Isfahan.