Earthquake analysis by response spectrum superposition

abstract Although earthquake response spectra can be used to determine the maximum response of structures having one degree of freedom, they provide only an approximate indication of the maximum response in multi-degree systems. In this paper, two different methods of approximating the maximum response, both based on superposition of the response spectra, are compared with exact analyses and the errors in the approximations are evaluated. Five different structures, each subjected to three different earthquake motions, are considered.