Ação do vento na estabilidade global efeitos de segunda ordem em estruturas de concreto armado na cidade de Belém-PA

Abstract

Due to the exponential growth of urban populations, the need for space for housing has grown significantly. To meet these demands, increasingly tall and slender buildings are designed, always aiming at the need to reduce costs and raise profitable margin by the construction companies. New materials and methods of structural analysis are created and improved so that maximum performance and structural safety are extracted at the lowest cost. Thus, this dissertation aims to contribute to the studies concerning the analysis of global stability and evaluation of the effects of 2nd order in the structures, from the comparative analysis of stability parameters, with the premises described in NBR 6118 (2014). In relation to the ultimate limit state, the following coefficients were evaluated: α and γz - suggested by NBR 6118 (2014), as well as FAVt and 𝑅𝑀2𝑀1 - obtained by the CAD/TQS System. With regard to the service limit state, the results concerning the horizontal displacements at the top of the buildings were analyzed and compared with the normative limits. For this, computational modeling was performed representing nine distinct fictitious structures submitted to the actions of the usual project loads on residential buildings, according to the aspects of NBR 6120 (1980), besides the evaluation of the influence of the consideration of the wind loads in the mentioned models structures. As for the development of the structures, usual techniques of discretization were employed, using the finite element method, through the CAD/TQS program. From the results obtained, it was observed that in the higher structures the parameters related to the ELU and ELS exceeded the normative limits, and that the fact regarding the lack of consideration of the wind action in the structures can significantly compromise the behavior and structural safety, since the calculated 1st and 2nd order final efforts can be up to 41% lower in relation to the efforts calculated by applying the criteria described in NBR 6123 (1988), in turn causing undersized structures and consequently, leading such structures to results catastrophic, such as ruin through progressive collapse.