Reliability-Based Evaluation of Load Factors using Beta Unzipping and Bayesian Methods


1 Dept. of Civil Engineering, University of Amirkabir, Tehran, Iran

2 Dept. of Civil Engineering, Amirkabir University of Technology, Hafez Ave, Tehran, Iran

3 Dept. of Civil Engineering, Amirkabir University of Technology, Hafez Ave, Tehran, Iran


In this study, various sources of uncertainty in demand and capacity and their direct and indirect dependencies according to their significant function in performance based earthquake engineering (PBEE), were incorporated proposing a practically new simple procedure. This procedure distinguishes and evaluates collapse probability of elementary mechanisms as well as computes their dependencies utilizing commonly used deterministic computer software through a full probabilistic methodology using β-unzipping and Bayesian methods. This procedure has been benchmarked for a typical 2D reinforced concrete moment frame and reliability index of the structure for the most probable collapse mechanism was obtained within a reliability-based framework. Moreover, the coefficients of dead, live and earthquake loads for a ACI load combination were reevaluated utilizing β-unzipping and Bayesian methods through the proposed procedure and were compared with the code's coefficients. Good compatibility between obtained coefficients and code's ones has been perceived and the probability of collapse, implicitly considered in the code, was revealed. It has been concluded that the coefficients extracted from Bayesian method are closer to the code's ones comparing to those from β-unzipping method; however, requiring less primary computational effort and slight differences between the results, β-unzipping is usually more preferred by evaluators.