Uma formulação mista para o projeto de consolos de concreto armado

Abstract

Corbels are structural elements of reinforced concrete generally connected to columns and whose function is to transfer loads to the main structure. The main loads acting on the corbels are vertical, coming from elements that rely on them. There may also be horizontal loads from shrinkage, deformation, creep or temperature changes of the beam-corbel assembly. They basically act as a cantilevered structure, but the ratio of the distance between the applied force and the center of the column (a) and the effective depth (d) is always smaller than the unit. This study is very important because as the ratio a/d is smaller than unity, the behaviour of the consolations cannot be compared to the behaviour of other structural elements. Although corbels are considered uniform, isotropic and perfect elastic materials, static and geometric discontinuities are observed in their structures, not obeying the Bernoulli Hypothesis. Due to the lack of more detailed study on the subject in question, this paper aims to find a new design model for the calculation of reinforced concrete corbels using methods already existing in the literature. Thus, several experiments with structural corbels elements were studied to find a suitable calibration, based on the shear-friction model, that works with some precision for very short corbels. After that, the calibrated shear-friction model was applied to 389 corbels obtained through the literature. Finally, the model proposed by Vieira (2018) based on the strut-and-tie method together with the shear-friction model proposed in this paper were used to perform a complementary weighting that defines the final formulation to find the calculated shear stress. The results obtained from this model were used to compare, through tables, graphs and statistical analysis, with those found in laboratory tests, obtaining satisfactory values.