Response of two-way eccentric building to nonuniform base excitations

Abstract

This paper studies the combined effects of structural eccentricities and nonuniform base excitations on the coupled torsional-lateral responses of two way eccentric building structures. The structural model used is a single-storey rigid diaphragm supported by four columns. The spatially varying multiple base excitations in the two horizontal directions are considered. Linear elastic structural responses are calculated by time history analysis. Spatially varying ground motion time histories are simulated for the analysis. The simulated time histories are individually compatible with the Newmark-Hall design response spectrum with 5% damping and normalized to 0.5 g, and are compatible with an empirical coherency loss function between each other. Analyses are carried out on the coupled torsional-lateral responses of torsionally flexible and torsionally stiff structures. Results are presented in terms of nondimensional parameters. It is found that nonuniform ground excitations reduce base shear, but induce torque in a building structure. Their effect is more significant than the structural eccentricity effect to torsionally flexible structure, but structural eccentricity effect is more pronounced to torsionally stiff structure.