Response Spectral Matching of Two Horizontal Ground-Motion Components

Abstract

Accurate performance-based earthquake engineering analysis requires that engineering seismologists and structural analysts employ consistent characterizations of bidirectional seismic demand. In current design, the seismic demand is generally given as a geometric mean response spectrum, which does not give a direct measure of the maximum spectral demand for all possible orientations of the ground motion with respect to the axes of the structure. Although this may be appropriate for most applications, it is shown that for some structures in which the lateral-load resisting system is not decoupled into two orthogonal subsystems, the maximum rotated spectral demand (major axis demand) may be the most appropriate characterization of bidirectional seismic hazard. On the basis of this observation, a new program is developed for matching the major and minor axis spectra of two horizontal ground-motion components simultaneously to two target spectra, using wavelets. The program,