RELIABILITY ASSESSMENT OF STRUCTURE SUBJECTED TO HORIZONTAL-VERTICAL RANDOM EARTHQUAKE EXCITATIONS

Statistical analysis of the response spectra due to both horizontal an d vertical ground excitations is conducted. A method is presented for generating a uniform hazard response spectrum making use of the seismi c hazard curve expressing annual probability of exceedance as a functi on of peak ground acceleration (PGA), a set of normalized mean respons e spectra, and a coefficient-of-variation function for the random norm alized spectral values in terms of period T. The response spectra of t he system are calculated by considering both horizontal and vertical e xcitations simultaneously. Comparison on the uniform hazard response s pectrum for case of single input (horizontal excitation only) and for case of multiple inputs (horizontal and vertical excitations) are made , It is important to note that the effect of load ratio (Mg/P-cr) as w ell as the PGA ratio between horizontal and vertical ground accelerati ons are two important parameters in the analysis of structural systems subjected to both horizontal and vertical ground motions. (C) 1997 El sevier Science Ltd.