Avaliação da distribuição de tensões em edifícios de alvenaria estrutural submetidos à variação de temperatura devido a incêndio

Abstract

Several studies and experiments related to the analysis of reinforced concrete structures in fire situations are found in the literature. However, in terms of masonry structures, there's no lots of studies to evaluate the aspects of fire, for example, in the loss of elements resistance, the redistribution of stresses and the occurrence of cracking. In addition, considering the peculiar characteristics of the structural masonry walls behavior and their differences when compared to reinforced concrete structures, it's not possible to apply indiscriminately the guidelines established for the analysis of this kind of structure to masonry structures. In this sense, the objective of the present work is to evaluate the distribution of stresses in the structural masonry walls submitted to variations of temperature corresponding to a fire occurrence in certain rooms of the apartment. The analyzes were made by results imported from computational modeling of a standard building with four pavements, using the equivalent frame model proposed by Nascimento Neto et at. (2014), which consists of the masonry discretization using finite elements of bar. Through this modeling, the deformations occurred in the slab of the pavement and the way that it interactes with the structural walls of the building were also verified. In addition, it was evaluated the possibility of using simplified analysis models to obtain these deformations and the corresponding stresses acting on the walls. From the obtained results it was possible to identify the occurrence of shear stresses with intensity above the limits currently established by the norms NBR 15961-1 and NBR 15812-1, indicating the need to perform reinforcement procedures on some walls of the sample building. The analyzes were complemented by the evaluation of the stresses redistribution in the walls in order to predict the probable cracking that can occur.