NONSTATIONARY RANDOM SEISMIC RESPONSES OF NONUNIFORM BEAMS

In this paper, a direct Ritz method is presented for analysing the res ponses of non-uniform shear beams subjected to the action of an evolut ionary random seismic excitation. Because of the use of a pseudo groun d acceleration, time-dependent random responses can conveniently be ca lculated by solving a set of deterministic equations of motion. These responses include power spectral densities, variances and higher spect ral moments of any required responses of the beam. A non-uniform beam example was solved and the time-dependent variances and second spectra l moments of both the beam-top displacement and the beam-base shear fo rce are given to show the simplicity and effectiveness of the method, which can also easily be applied to other continuous elastic structure s.