Aberturas em lajes maciças de concreto armado: análise da sua influência no dimensionamento estrutural através do método de bielas e tirantes

Abstract

Openings in slabs are commonly seen in buildings, since this is a very usual and necessary solution for passages of water lines, sewage, data, among others. Its correct execution is of paramount importance to avoid cracks in the constructive element. To be successful on that, a specific reinforcement must be designed for this region. Therefore, this work analyzed the influence of these openings regarding their positioning and dimension in the resistance of the slabs in which they are used. For this research, the Brazilian standard ABNT NBR 6118:2014 was used, which determines how the design of massive slabs in reinforced concrete and the openings should be done. In this work it, was also exposed what types of materials are used and the calculation method for dimensioning the used constructive elements. In order to reach the proposed objective, an analysis matrix of 10 identical slabs was elaborated, with different types of openings and positions, with this, their reinforcement could be dimensioned with the help of the TQS software, and then, using the same program, be able to get results from displacements. Applying the method, it was found that the further to the middle of the slab and the larger its opening, the greater was the impact generated on the deflection of the structural element. Much further, it was found that the best position for the opening would be in the corner of the slab, since the displacements increased considerably when these openings were located in the middle of the structural element. For the determination of reinforcing reinforcements, the empirical method of Leonhardt and Mönning was used, which consists of the simple interruption of bars, and then this result was compared with what was calculated using the strut-and-tie model, which consists of finding the forces acting around the opening and then applying them to the idealized truss, thus determining the acting loads. With this, it was possible to determine a required steel area. With these results, it was observed that the empirical method of Leonhardt and Mönning presented, throughout the analysis matrix, a greater steel area than that obtained by the strut-and-tie model, thus being the most suitable for these situations. [resumo fornecido pelo autor]