EVALUATION ON COMMONLY USED GROUND MOTION SELECTING AND SCALING METHODS WITH PRACTICAL COMMENTS

This study compares the reliability of six commonly used ground motion selecting and scaling methods for the structural seismic response assessment. Results based on a total of 400 records which are selected from the PEER strong ground motion database and compatible to the earthquake environment are used as the benchmark seismic responses of structures. Using the six methods, records of 7-ground-motion set and 3-ground-motion set for each method are selected from the database and scaled to the design earthquake intensity. An engineering demand parameter, i.e., EDP (the inter-story drift ratio), of a 4-story and a 16-story frame structures are calculated with these sets of records. The accuracy of the six methods are examined by comparing the EDP against the benchmark seismic responses. For the 7-ground-motion set, the results demonstrate that the double frequency control and modal pushover scaling methods could provide more accurate evaluation results comparing with other methods. The maximum seismic responses predicted by the 3-ground-motion set may be conservative to the average seismic response predicted by the 7-ground-motion set. If each story of a structure is considered, almost none of the six methods could predict totally conservative inter-story drift ratio results when considering 1 or 2 standard deviations.