Fragility analysis and seismic record selection

This paper explores the influence of spectrum-matched and amplitude-scaled ground motions on the development of fragility functions for structures. The quantification of the influence of these two types of ensembles on ground motions in predicting demands of structural and nonstructural systems is addressed. Moreover, the paper investigates the sensitivity of number of accelerograms in the ensembles, which produces consistent results in the nonlinear analyses. A multidegree-of-freedom (MDOF) inelastic shear-type building is used in the evaluations. The median and the dispersion of different types of damage measures are evaluated at each story and the effect of different levels of nonlinearity is investigated. Fragility functions are developed for structural and nonstructural components using the maximum likelihood method from the response generated with the selected ground motions. The sufficient number of ground motions necessary in the estimation of the response parameters and on the evaluation of the fragility functions is presented herein.