Estudo da confiabilidade estrutural de sapatas submetidas a cargas centradas dimensionadas pelo CEB-70

Abstract

Foundation structures are the ones responsible for the safe transmission of the loads acting on the structure to the soil, and its designs are developed through deterministic means. The structural reliability methodology, on the other hand, use a probabilistic approach, enabling the consideration of the uncertainties relative to the project variables in the safety assessment of the structure. The solution of the structural reliability problem can be attained through both transformation and simulation methods. This paper proposes the structural reliability analysis of axially loaded sloped footings designed by CEB-70. The employed methods for the attainment of the reliability indexes were the First Order Second Moment method (FOSM), the First Order Reliability Method (FORM), the Second Order Reliability Method (SORM) and the Monte Carlo Simulation Method with Importance Sampling using Design Points (SMC-PP). It was noted that the values of the reliability indexes obtained for de CEB- 70 design suited the minimum recommended by the European and American norms. It was possible to note similar values obtained by the FORM, SORM and SMC-PP methods, and a high difference of the FOSM method regarding the others. It was observed a high influence on the probability of failure of the structure regarding the live loads and uncertainty of the resistance models variables, pointing to the importance of studying these variables. Furthermore, it was noted that the increase of both the steel area and height of the sloped footing contribute positively to the reliability index of the structure, and can be used for the reliability based design of the structure.