Desenvolvimento de ferramenta computacional considerando o efeito de membrana na verificação estrutural de lajes mistas em situação de incêndio

Abstract

Studies on fires, both related to firefighting and to the load-bearing capacity of structures, have increased in recent years due to economic losses and fatalities. This work aims to develop a computational program for the design of composite slabs subjected to high temperatures considering the membrane effect, using symmetric and asymmetric welded mesh reinforcement. ABNT NBR 14323:2013 provides guidelines for the design of these structures by neglecting the contribution of the steel deck in its calculations and, consequently, requires the use of positive reinforcement; however, it does not account for the impact of the amplification coefficient caused by the membrane effect on the load-bearing capacity of the slab, thus making the design very conservative and uneconomical. The methodology consists of applying the method developed by Bailey (2001), which considers the membrane effect in slabs subjected to elevated temperatures. Results from the program developed in this research were analyzed using temperatures obtained from thermal analysis, as well as through the use of the computational program MACS+ for slab analysis with symmetric and asymmetric welded meshes. The results proved to be conservative when compared to the temperatures from EN 1994-1 2:2014, while the reinforcement ratio showed a particularly significant influence on the results. For meshes with smaller steel areas, a more uniform trend of increasing load-bearing capacity with increasing slab thickness was observed