Avaliação da contribuição das vigas de contorno na estabilidade global de edifícios com lajes lisas protendidas

Abstract

The use of prestressed concrete in buildings is gaining more and more space in Brazil. Problems that often cannot be solved with conventional reinforced concrete are easily overcome using this structural solution. In addition, the use of prestressed concrete brings architectural versatility, as it reduces or even eliminates the need for beams, which means that the removal of walls, for example, does not cause an unwanted exposure of beams. However, without the beams, the portico effect does not happen, leaving all responsibility for the overall stability of the structure to the rigidity of the slabs and pillars, which can affect the functioning of the structure as a whole. Thus, this work evaluates the effects of considering or not the beams in the contour of the single slab of a 6-story building in post-tensioned prestressed flat slabs with limited non-adherent prestressing. The analysis is carried out using the AltoQi Eberick software with the prestressed slabs module, comparing a model with prestressed flat slabs supported directly on the pillars and another model with the slabs supported on beams along their entire contour. The comparison of results between the models was based on the slopes of the slabs and the horizontal displacements of the buildings for the service limit state, where a reduction of these values was observed; in the coefficient 𝛾𝑧, which presented a reduction in its value, representing an improvement in the global stability for the ultimate limit state with the insertion of the beams; and differences in the effective steel area between the pillars of the models, which also showed a reduction.