Reliability analysis of nonlinear MDOF dynamic systems

This paper presents a simplified procedure to estimate the probability of failure for nonlinear MDOF shear-type systems optimally designed due to the seismic excitation. The excitation is idealized as a nonstationary stochastic process. With the aid of the response modification factor-ductility factor relationship established by the authors for these systems, 'an equivalent linear criteria' of such systems is introduced. Then, a linear response and the equivalent criteria can be used to evaluate the limit state probability as a solution to the classical first excursion probability problem at least in approximation. An example of a three-story building is demonstrated and the results are compared by using a simulation method. (orig.)