Global Seismic Reliability Analysis of Building Structures Based on System-level Limit States

In this paper, a global limit state function for load-carrying capacity of structural system is firstly set up, in which the margin of safety is the difference between the limit base shear of structural system and the total horizontal seismic action. To probabilistically assess the global seismic capacity of structure, a new point estimation method (PEM) for analyzing statistical moments of complex random function is put forward, and then it is combined with deterministic finite element analysis to produce the so-called “random pushover analysis (RPA)”. On the basis of the above new methodologies, a semi-analytical approach which integrates the improved point estimation method, pushover analysis and first order reliability method (FORM) is developed to analyze the nonlinear seismic reliability of structure as a global system. By applying the proposed approach in R.C. frame structure, the changing rules of the global seismic reliability of the structure with the coefficient of variation of the total seismic action and correlation coefficient of storey-level seismic forces are derived. It is demonstrated by a numerical example that the newly developed method in this paper is simple, practical and efficient compared with MCS, and that it has the same accuracy as MCS.