Dimensionamento de lajes lisas em concreto protendido com variação da resistência característica à compressão do concreto utilizando o TQS

Abstract

Designed for structures with slender elements and longer spans, prestressing has emerged as an alternative to reinforced concrete. It applies compressive stresses to the areas of the concrete subject to traction, minimizing or eliminating the tensile stresses responsible for cracking and increasing the durability of the structure. The combination of high-strength steels and higher-strength concrete makes it possible to create slimmer sections, reducing the dimensions of the cross-section and making the structures lighter. In this sense, the main objective of this work is to design prestressed concrete flat slabs using the TQS software, varying the characteristic compressive strength of the concrete (fck) from 30 MPa, the minimum allowed by the Brazilian standard, to 40 MPa and 50 MPa, checking how this parameter influences the behavior of the slab. The results show that by increasing the fck of the concrete, it is possible to reduce the displacements or the number of prestressing cables. However, this increase is associated with an increase in the minimum passive reinforcement. When the number of cables is reduced, there is an increase in cracking, although within the permitted limits, and a decrease in prestress loss. A comparison between TQS models IV and VI reveals that model VI is closer to the real behavior of the slab, since it takes into account the influence of horizontal forces, such as those resulting from prestressing. As a result, the calculation of the slab's displacements is more accurate.