Seismic Response of Asymmetric Structures to Multiple Ground Motions

Abstract

If ground motion is not uniform over a building's base, or if the building is asymmetric, torsional response occurs. This paper investigates the effect of torsional coupling induced by both multiple ground excitations and building asymmetry on earthquake forces. The system studied is an idealized single-story two-degrees-of-freedom building model with four supports. Spatially varying ground excitations at the supports are used. Thirty sets of spatially correlated ground-motion time histories are simulated for the analysis. Each set of the simulated time histories are compatible with an empirical coherency loss function of recorded motions, and they are also individually compatible with the Newmark-Hall response spectrum with 5% damping and normalized to 0.5