Weighted and Unweighted Scaling Methods for Ground Motion Selection in Time-history Analysis of Structures

A weighted scaling method (WSM) is developed for the selection and modification of structure-specific earthquake records in time-history analysis. The matching errors and scaling factors are calculated by weighted least-squares method to match with target spectrum. The weight factors are determined by the modal-mass participation factors. The 3-, 9-, and 20-story steel moment-resisting frame structures are used as examples. Their mean structural responses were calculated by the WSM and the unweighted scaling method (USM). WSM is as accurate as USM for estimating mean structural responses, but WSM has a better capacity for reducing the variability of structural responses.