Probabilistic Analysis of Immediate Settlement of a Rectangular Foundation Using Various Reliability Software

Study of immediate settlement of a rectangular foundation with the task of transferring structural forces to the ground, is one of the important factors in the design of structures. Due to its heterogeneous and anisotropicnature, soil parameters have highuncertainties, the omission of which in estimating the settlement of foundation, creates challenges in the analysis of structural stability. Therefore, the use of reliability methods with the ability to accept uncertainties and reliable stability analysis of geotechnical issues are welcomed today. In this study, in order to estimate the probability of failure due to settlement of rectangular foundation, first-order and second-order reliability methods as well as Monte Carlo simulations were used and the relevant analysis were performed in RT and @Risk software.The results indicate a high probability of failure related to the foundation settlement (9.5%). The second-order methods and Monte Carlo simulations provide more accurate results due to the non-linearity of the limit state procedure. In addition, the sensitivity analysis of random variables based on sensitivity vectors showed that thecontact stress (qo), has an important role in the probability of failure, and then the Poisson’s ratio is important.