Fragility analysis

The fragility analysis evaluates the conditional fraction of failure of plant structures and equipment as a function of ground motion. The seismically initiated failure of plant components is expressed in terms spectral acceleration at 5.0 Hz which is between the fundamental frequency of the... 

Technical report NCEER-87-0015, State University of New York, Buffalo Erberik MA, Elnashai AS (2004) Fragility analysis of flat-slab structures. Eng Struct... 

Kircil MS, Polat Z (2006) Fragility analysis of mid-rise R/C frame buildings. Eng Struct... 

Casciati, F. Faravelli, L. 1991. Fragility Analysis of Complex Structural Systems. Taunton Research Studies Press Ltd. 

Currently, the assessment of seismic capacity is being carried out to comply with the relevant IAEA recommendations. In addition, a probabilistic seismic hazard analysis is included in the Temelin PSA Project scope in order to address the contribution from earthquake induced accident sequences to the overall CDF of the plant. The seismic hazard curves for the Temelin site has been developed and seismic fragility analysis has been performed for the structures and components. Based on the preliminary results (annual frequency of O.lg PGA (SSE) earthquake is lE-6/year), it is expected that the contribution of seismic events and the consequential accident sequences to the overall CDF will be negligible (i.e. less then 1% of overall CDF). The independent review of this PSA task is to be carried out in the framework of the 2nd IAEA IPERS (Level 1 - external initiating events) in August/September 1995. 

Bocchini, P. Frangopol, D.M. 2011. A stochastic computational framework for the joint transportation network fragility analysis and traffic flow distribution under extreme events. Probabilistic Engineering... 

Fragility analysis Fragility curve Limit state Nonlinear static procedure Pushover analysis SDOF model Seismic demand Target displacement Uncertainty... 

It should be noted that the main objective of this entry is to introduce the use of conventional pushover-based method for fragility analysis, taking into account the randomness of grotmd motion and the epistemic (modeling) xmcertainty. Thus, not all issues associated with pushover-based methods are precisely addressed. 

The result of fragility analysis is the fragility function, which represents the probability that an engineering demand parameter (EDP) will exceed a certain limit-state value edp given an intensity IM = im. In the simplest case, it is assumed that the seismic fragility function is based on a lognormal distribution function ... 

However, all the referenced procedures are based on simulations which are performed at the level of a MDOF model. Recently, an approximate procedure utilizing a deterministic MDOF model and uncertainty analysis at the level of a SDOF model was proposed (Kosic et al. 2014). It can be classified as being somewhere in between the aforementioned procedures for the determination of fragility parameters on the basis of pushover methods, both in terms of computational time and in terms of accuracy. Such an approach is computationally less demanding, since all the simulations are performed at the level of the so-called probabilistic SDOF model. It can therefore be attractive for the fragility analysis of more extensive building stock. 

Example Pushover-Based Seismic Fragility Analysis of the RC Frame Building With Consideration of Ground-Motion Randomness and Modeling Uncertainty... 

A simple variant of a pushover-based fragility analysis is demonstrated by means of an illustrative example. The procedure involves conventional pushover analyses and the nonlinear dynamic analyses of corresponding SDOF models. The effects of ground-motion and modeling uncertainties are accounted for, respectively, by the set of ground motions and the set of structural models which are generated by Monte Carlo with LHS. The step-by-step procedure for the determination of the fragility curve is as follows ... 

Step 2. Fragility analysis was performed for the limit states of damage limitation (DL), significant damage (SD), and near collapse (NC), as defined in Eurocode (CEN 2005). It was assumed that the DL limit state is attained at the structural level if the longitudinal reinforcement in all the columns in any story starts to yield. It was further assumed that the SD and NC limit states are reached, at the structural level, when the moment exceeds the maximum moment in the case of the first column or the rotation exceeds the ultimate rotation in the case of first column, respectively. However, additional criteria for the occurrence of the SD and NC limit states were... 

Step 4. Realization of the random variables was based on the LHS technique. The size of the sample was assumed to be equal to 20, which is slightly larger than twice the number of all the random variables considered in the fragility analysis. The correlation matrix of the sample was almost identical to the target correlation matrix. Note that this is only a necessary condition for the prediction of the seismic response parameters with the required accuracy, whereas the sufficient condition is related to the number of simulations, which is, in the case of the example, relatively low ( sim = 20). However, the results of performed studies have shown that, in the case when Nsim is larger than twice the number of random variables an increase in the... 

Bayesian statistics Earthquake probabilities Fragility analysis Ground motion simulation Seismic activity matrix Seismic hazard Seismo-logical model... 

Kafali C, Grigoriu M (2010) Seismic fragility analysis application to simple linear and nonlinear systems. Earthq Eng Stract Dyn 36(13) 1885-1900 Koutsourelakis P (2010) Assessing structural vulnerability against earthquakes using multi-dimensional fragility surfaces a Bayesian framework. Probab Eng Mech 25 49-60... 

Learning from Earthquake Disasters Probabilistic Seismic Hazard Models Seismic Fragility Analysis... 

Kafali C, Grigouri M (2004) Seismic fragility analysis. In Proceedings of the 9th ASCE specialty conference on probabilistic mechanics and stmctural reliability, Rome, 19-23 June 2005... 

Seismic Fragility Analysis Soil-Structure Interaction... 

Seismic fragility can be defined as the proneness of a structural component or a system to fail to perform satisfactorily under a predefined limit state when subjected to an extensive range of seismic action, fri accordance with the above definition, seismic fragility analysis can be regarded as a probabilistic measure for seismic performance assessment of structural components or systems. There are two different end products of seismic fragility analysis damage probability matrix and fragility curve. 

Seismic Fragility Analysis, Fig. 1 Conversion from a set of fragility curves to DPM (Prepared by using the data from... 

Basically, seismic fragility analysis is the comparison of seismic capacity and demand and to estimate whether the seismic capacity is exceeded for a well-defined performance level when the structural system is subjected to specified levels of ground motion intensity. Due to the probabilistic nature of seismic fragility analysis, both seismic capacity and demand are defined by probability functions in terms of certain random variables to quantify all the uncertainties involved in the process. 

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