Análise global de edifícios de concreto: efeitos de segunda ordem devidos à torção e efeitos de desaprumo

Abstract

The structural analysis is one of the fundamental steps in structural design development. The structure’s global analysis allow the determination of forces, stresses, displacements and strains, which are information necessary for the structural design. Despite the importance of structural analysis, some aspects of this process might not be easily found in publications or always be present in practical project development. Various considerations and hypothesis related to global geometric imperfection are not necessarily clear in the Brazilian Standard Code ABNT NBR 6118:2014. In addition, torsion effects on buildings` structural analysis and its influence in structures` second order behaviour might be partially accounted, as they are not completely included in simplified methods to account for second order effects such as the coefficient γz. This text focus on both these subjects in the context of global analysis of concrete structures. Thus, it is used the coefficient γθ, a proposition analogous to the coefficient γz, for the consideration of second order effects due to torsion. The rotational displacements on didactic models are calculated and compared with those obtained with a P-∆ method analysis. In addition, information related to the considerations of out-of-plumb buildings are sought and gathered, so that the expressions present in ABNT NBR 6118:2014 on the subject are better understood. A structure is analysed in order to verify some of the consequences of the consideration of the number of elements in the out-of-plumb effect and the Brazilian code regulations on the superposition of the wind and out-of-plumb actions in the global analysis.