Influência da utilização dos coeficientes de redução de cargas variáveis no dimensionamento de uma edificação em concreto armado

Abstract

This paper presents the study about the adoption of multipliers αn of variable loads contained in ABNT NBR 6120/2019, and how their use impacts on the internal forces and, therefore, on the design of the structure of a reinforced concrete building. According to ABNT NBR 6120/2019 this reduction criterion can be applied for buildings with different types of use, to each set of adjacent floors of the same type of use. It is worth making it clear that the application of the coefficients is not mandatory, so it is up to the structural engineer to do it or not. For the study, it was chosen to use four different floor numbers for the same architecture: 8, 12, 16 and 20. For this, the four buildings were modeled in TQS V22 software imposing the proper permanent and accidental loads on the structural elements, as well as the wind load related to the building location. The first analysis of efforts and design of the structural elements was done for the structure with permanent and variable integral loads, without the use of the reducer. After that, the load reduction coefficients were adopted for all floors, except for the roof and first floor, correctly following the standard criteria. It was concluded that although there are load reductions as the number of floors increases, the efforts in the foundations do not reduce enough to have a change in the consumption of concrete and steel. The columns of the 8, 12 and 16 floor buildings presented a significant reduction in steel consumption, but for the 20 floor building there was a smaller influence. This conclusion should not be generalized because it is based on the floor plan and number of floors adopted for this research.