Cálculo de deslocamentos em lajes nervuradas

Abstract

This work has as main objective to contribute for the development of a methodology capable to determine through numerical simulations the displacements in waffles slabs, submitted to uniformly distributed loading. It was analyzed a unidirectional waffle slab and another bidirectional, applying the method of the homogeneous equivalent material for the determination of the behavior of the transversal section of the ribbing. The materials had been characterized from the recommendations of NBR 6118 and also for the analyses carried through the authors of the reference slab, that will serve for the validation of this work. With the job of finite elements of bar and hexaedrals with twenty nodes, it was simulated the structure of the unidirectional waffle slab, getting as main result, the displacements at the center span. One evidenced that the model with hexaedrals finite elements of twenty we represented of satisfactory form the behavior of the structure. For the finite elements of bar, similar curves with behavior the actual structure, but with values of displacements below of the experimental values was obtained. On new analysis, it was verified that the used finite element did not consider all the characteristics of the T section, identified a correction factor, resultant of the ratio of the width table and the ribbing width, to be applied to the obtained values, generating a corrected load-displacement diagram. These last results had presented compatible values with the real structure. For the analysis of the bidirectional waffle slab, the option for the use of assay carried through in reduced model was made, applying the method with bar finite elements, through a grate. In the determination of the equivalent homogeneous material had been grouped the ribbings in bands, in accordance with the similarity of the form and the reinforcemente, generating a mechanical behavior for each band. The results also had been corrected by the correction factor, coming close themselves to the experimental values, except in edges of the slab where the influence of the negative moments are bigger. Thus, it was contributed for the development of a methodology capable to calculate the displacements in the waffle slabs.