Assessing the Effects of Record Selection and Ground-Motion’s Spectral Shape on the Collapse Capacity of the Structures

Abstract

Selecting and scaling the set of ground-motion records is among the most important challenges in collapse capacity assessment and estimation of structures. In this study, 44 records were considered to estimate the collapse capacity of the structure.Next, the response spectrum matching degree of each ground-motion with the conditional mean spectrum at the inspected hazard level was employed to account for the effect of record selection on the collapse capacity of the structure and appropriate records were selected per each hazard level. Further, the spectral shape factor or epsilon was used to incorporate the effect of spectral shape on collapse capacity. In the first approach, the collapse capacity of the structure was modified for the overall set of selected ground-motions via epsilon according to the level of inspected hazard. In the second approach, the simplified method introduced by Haselton et al. was used to assess the effect of epsilon and modify the collapse capacity of the structure at the inspected hazard level. The results of the modified collapse capacity at the inspected hazard level were collected from three respective methods of record selection. These data were collected using the overall set of ground-motions with the epsilon and the simplified method. The obtained results indicate that the ratio of modified collapse capacity with the effects of record selection and epsilon on collapse capacity, disregarding the record selection and epsilon effects, are 1.216, 1.174, and 1.197 at the hazard level of 2% in 50 years for the three discussed methods, respectively. Ultimately, these three individual methods have rendered approximately equal estimates.