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Structural Engineering and Mechanics
  Volume 36, Number 1, September10 2010 , pages 19-36
DOI: https://doi.org/10.12989/sem.2010.36.1.019
 


Estimation of load and resistance factors based on the fourth moment method
Zhao-Hui Lu, Yan-Gang Zhao and Alfredo H-S. Ang

 
Abstract
    The load and resistance factors are generally obtained using the First Order Reliability Method (FORM), in which the design point should be determined and derivative-based iterations have to be used. In this paper, a simple method for estimating the load and resistance factors using the first four moments of the basic random variables is proposed and a simple formula for the target mean resistance is also proposed to avoid iteration computation. Unlike the currently used method, the load and resistance factors can be determined using the proposed method even when the probability density functions (PDFs) of the basic random variables are not available. Moreover, the proposed method does not need either the iterative computation of derivatives or any design points. Thus, the present method provides a more convenient and effective way to estimate the load and resistance factors in practical engineering. Numerical examples are presented to demonstrate the advantages of the proposed fourth moment method for determining the load and resistance factors.
 
Key Words
    load and resistance factors; fourth moment method; target mean resistance; simple formula.
 
Address
Zhao-Hui Lu: School of Civil Engineering and Architecture, Central South University, 22 Shaoshannan Road, Changsha 410075, China
Yan-Gang Zhao: Department of Architecture, Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan
Alfredo H-S. Ang: Department of Civil and Environmental Engineering, University of California, Irvine, E-4150 Engineering Gateway, Irvine, CA 92697-2175, USA
 

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