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 $e/r\text{,}$ the uncoupled torsional to lateral frequency ratio Ω, the beam‐to‐column stiffness ratio ρ, and the uncoupled, fundamental, lateral vibration period $T_{\mathrm{y1}}\text{.}$ It is concluded that the response contributions of the higher vibration modal pairs increase with increasing $T_{\mathrm{y1}}\text{.}$ and decreasing ρ. However, if $T_{\mathrm{y1}}\text{.}$ 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 $T_{\mathrm{y1}}\text{.}$ is in the acceleration‐controlled region of the spectrum.