EARTHQUAKE ANALYSIS OF ISOTROPIC ASYMMETRIC MULTISTORY BUILDINGS

摘要

Isotropic multistory buildings are the ones characterized by the property: all load-resisting planar frames have proportional lateral stiffness matrices. In the present paper it is proved that the modal analysis of an N-story isotropic asymmetric, torsionally coupled, building (a problem of order 3N) can be separated into two independent sub-problems: (a) a sub-problem that corresponds to a single-story asymmetric, torsionally coupled, building (a problem of order 3); and (b) a sub-problem that corresponds to an N-story, torsionally uncoupled, planar frame (a problem of order N). It is also demonstrated that the orientation of peak modal seismic forces of the building is independent of the orientation of seismic excitation, which affects only their size. The separation provides a better insight into the structural behavior of asymmetric multistory buildings under earthquake ground motion.