Practical Guidelines to Select and Scale Earthquake Records for Nonlinear Response History Analysis of Structures

ABSTRACT

Earthquake engineering practice is increasingly using nonlinear response history analysis (RHA) to demonstrate performance of structures. This rigorous method of analysis requires selection and scaling of ground motions appropriate to design hazard levels. Presented herein is a modal-pushover-based scaling (MPS) method to scale ground motions for use in nonlinear RHA of buildings and bridges. In the MPS method, the ground motions are scaled to match (to a specified tolerance) a target value of the inelastic deformation of the first-“mode” inelastic single-degree-of-freedom (SDF) system whose properties are determined by first-“mode” pushover analysis. Appropriate for first-“mode” dominated structures, this approach is extended for structures with significant contributions of higher modes by considering elastic deformation of second-“mode” SDF system in selecting a subset of the scaled ground motions. Based on results presented for two bridges, covering single- and multi-span “ordinary standard” bridge types, and six buildings, covering low-, mid-, and tall building types in California, the accuracy and efficiency of the MPS procedure are established and its superiority over the ASCE/SEI 7-05 scaling procedure is demonstrated.

First posted July 9, 2010