A PROPOSAL FOR SAFETY FACTOR ESTIMATION IN SEISMIC PSA OF STRUCTURE BY STOCHASTIC FEM TECHNIQUE

The study of safety factor estimation in seismic probabilistic safety assessment has been a focus of researchers' interest for some time. Mo st of the papers dealt with the safety factor estimation by means of e xperimental knowledge or numerical analysis such as the Monte Carlo te chnique. This paper presents a new method to gain parts of structural response factors analytically by utilizing the statistical theory of e xtremes and the stochastic FEM technique. First, the stochastic FEM is adopted to obtain the statistical response values considering the unc ertainty of structural material, through the spectral analysis due to an earthquake as a stationary random process. As second step, combinin g the results by statistical theory of extremes for a structure having deterministic material properties with the previous results by spectr al analysis considering material uncertainty, with the aid of the tota l representation theorem against uncertainty modeling, statistics rela ted to maximum values of response could be calculated under the consid eration of structural material uncertainty. Those results are shown in good agreement with Monte Carlo simulation. Finally, using the obtain ed results, it is shown how to get the structural safety factors relat ed to structural material uncertainty analytically.