Systematic assessment of irregular building-soil interaction using efficient modal analysis

In this paper an efficient methodology applying modal analysis is developed to assess systematically the combined soil-structure interaction and torsi onal coupling effects on asymmetric buildings. This method is implemented i n the frequency domain to accurately incorporate the frequency-dependent fo undation impedance functions. For extensively extracting the soil-structure interaction effects, a diagonal transfer matrix in the modal space is deri ved. A comprehensive investigation of asymmetric building-soil interaction can then be conveniently conducted by examining various types of response q uantities. Results of parametric study show that the increasing height-to-b ase ratio of a structure generally amplifies its translational and torsiona l responses. Moreover, both the translational and torsional responses are r educed for the case where the two resonant frequencies are well separated a nd this reduction is enhanced with the decreasing values of the relative so il stiffness and the height-to-base ratio. The most noteworthy phenomenon m ay be the fact that the SSI effects can enlarge the translational response if the structure is slender and the two resonant frequencies are very close . Copyright (C) 2001 John Wiley & Sons, Ltd.