Reliability Analysis of Serviceability Limit States of Beams in a Benchmark Reinforced Concrete Building

Resumo

The construction system of reinforced concrete entails inherent uncertainties concerning its execution method, as well as physical, chemical, and biological phenomena, along with the loads acting on buildings. Hence, understanding and characterizing random variables in designing reinforced concrete structures is pivotal for devising effective solutions that meet safety and performance requirements. In this context, limit state equations are employed for structural analysis and design, addressing different failure modes, while concepts of probability and statistics are utilized alongside reliability methods to ascertain the probability of failure and assess the structural integrity of the elements. Within this framework, this study endeavors to implement models for evaluating the reliability levels of reinforced concrete beams in a 2-storey building, considering the limit states of excessive deflection and crack width, and incorporating the effects of shrinkage and creep, according to NBR 6118:2023. The probabilistic assessment of the designed beams is performed by using the First-Order Reliability Method (FORM), whose results are validated and compared with those obtained through the Monte Carlo simulation method. The findings indicate a conservative design of the beams for the failure modes addressed, as the reliability indices are in line with values stipulated by international standards in most cases analyzed. Although this, some critical beams subject to higher loads approached the allowable limits more closely, presenting a narrow safety margin. This study aims to contribute to the advancement of integrating reliability analyses into reinforced concrete structural projects.