Analysis of Coupled Lateral-Torsional-Pounding Responses of One-Storey Asymmetric Adjacent Structures Subjected to Bi-Directional Ground Motions Part II: Spatially Varying Ground Motion Input

Abstract

This is the second paper presenting numerical results of a parametric study of seismic induced lateral-torsional-pounding responses of an asymmetric and a symmetric one-storey adjacent structure. The accompany paper (Part I) (Gong and Hao 2004) assumed ground motion input at all structural supports as uniform. Torsional responses are generated because of inherent structural eccentricity and eccentric pounding. In reality, seismic ground motion at different structural supports inevitably varies owing to wave propagation. Spatially varying ground motion will induce torsional responses of structures, and generate out-of-phase responses between adjacent structures. Thus it might have a significant effect on coupled lateral-torsional-pounding responses. This paper studies the ground motion spatial variation effect. For comparison purpose, same adjacent structure models and impact element used in Part I of this study are adopted here again. 20 sets of spatially varying ground motion time histories are stochastically simulated. All the time histories are compatible with the Newmark-Hall design response spectrum with 5% damping and normalized to 0.5g. The spatial variation of any two simulated time histories is compatible with an empirical coherency loss function. Coupled lateral-torsional-pounding responses of the two structures to the simulated ground motions are calculated. Discussions on the ground motion spatial variation effects are made.