Approximate Incremental Dynamic Analysis Using Reduction of Ground MotionRecords

Incremental dynamic analysis (IDA) requires the analysis of non-linear response history of a structurefor an ensemble of ground motions, each scaled to multiple levels of intensity and selected to cover theentire range of structural response. Recognizing that IDA of practical structures is computationallydemanding, an approximate procedure based on the reduction of the number of ground motions isdeveloped. A methodology based on data envelopment analysis (DEA), mathematical programmingthat can handle large numbers of variables and relations, is proposed to reduce the number of groundmotions needed for the production of a reliable median IDA curve. The IDA curves computed by theexact and approximate procedures for two different sets of ground motions for the 9-storey SAC-LosAngeles building are presented. The results demonstrate that the approximate procedure, which uses alimited number of input ground motions, is accurate enough for practical application in buildingevaluation and design.