Earthquake Response of Torsionally Coupled, Frame Buildings

The earthquake response of torsionally coupled buildings is presented for a wide range of system parameters. Based on these results, it is demonstrated that the building response depends significantly on the static eccentricity ratio e/r, the uncoupled torsional to lateral frequency ratio Ω, the beam‐to‐column stiffness ratio ρ, and the uncoupled, fundamental, lateral vibration period Ty1. It is concluded that the response contributions of the higher vibration modal pairs increase with increasing Ty1. and decreasing ρ. However, if Ty1. is in the accelerationor velocity‐controlled regions of the earthquake design spectrum, the first two vibration modal pairs are sufficient to estimate the response to a useful degree of accuracy; the fundamental vibration modal pair suffices if Ty1. is in the acceleration‐controlled region of the spectrum.