Structural reliability of reinforced concrete beams in flexure: A comparison between FORM and Monte Carlo Simulation

Resumo

Structural reliability represents a fundamental discipline in structural engineering, enabling the quantitative assessment of safety by addressing the inherent variability of actions, geometric and mechanical properties of structural elements, and parameters of constitutive models. This study aims to contribute to the advancement of this field by developing computational tools for the reliability analysis of reinforced concrete beam sections subjected to simple bending, explicitly considering the stochastic behavior of the involved variables.The research employs two approaches: a numerical simulation method (Monte Carlo Simulation, MCS) and a transformation method (First Order Reliability Method, FORM), both based on two-dimensional modeling and grounded in established codes and technical literature.Two computational algorithms are developed to evaluate the reliability of rectangular cross-sections designed according to the ACI-318-19 code. These algorithms are applied to representative sections, accounting for typical ratios of permanent to variable actions observed in building structures. The methods are compared in terms of accuracy, computational efficiency, and applicability. Furthermore, a sensitivity analysis is conducted to identify the influence of random variables on reliability indices and failure probabilities.The proposed algorithms are also applied to case studies involving deviations from initial design assumptions, such as variations in actions, material strength degradation, and construction inaccuracies, allowing for an in-depth evaluation of their effects on structural safety.