The Reliability of the Foundation Seismic Design Using Iranian National Building Code

Deterministic approaches, such as allowable stress design (asd), and load and resistance factor design (lrfd), which are proposed by iranian national building code, are widely used for seismic foundation design. as almost all the engineers’ community know, the deterministic methods cannot provide a transparent view of the risk level of the designs. hence, determining the reliability ranges of the mentioned methods can aware us about the circumstances into which we are faced. in this paper, a practical probabilistic approach proposing by low 1996 is employed to calculate the reliability indexes of the design methods following the iranian code (7th part). numerical results of this research indicate that although both methods cannot meet the appropriate target reliability (3-4), the reliability of the lrfd method is better than the asd. the differences between the reliability of these two methods will be more considerable in the granular soil deposit. a significant result shows the reliability will decrease by either increasing the slope angle or region seismicity. given the indicated point, it can be concluded that using iranian code (asd, and lrfd) cannot yield a reliable design. therefore, this can pose a high risk, a risk which should be considered. it is essential to note that the mentioned analyses and obtained results in this paper are mainly based on some few examples with assumed values for different factors. for the research to be more widespread, comparison of these results with real behavior of the foundations, built in recent years following the iranian code is needed. notwithstanding, this study can give us a clue that seismic foundation designing utilizing iranian code in different circumstances can lead to a broad spectrum of reliability.