Influence of structural system on shear capacity of wide members without shear reinforcement

 With my colleagues in Brazil, we have been working on further analysis of database results. As a result, the paper “Influence of structural system on shear capacity of wide members without shear reinforcement” was accepted for presentation at the virtual fib Shanghai symposium and published in November.

The abstract of the article is as follows: 

Most models of shear strength used to estimate the shear capacity of wide reinforced concrete members without shear reinforcement do not take into account the structural system or the support conditions. However, some experimental results indicate that bending moment can have a positive influence on members with predominant flexural action, contrary to most of the mechanical models governed by tensile strain in the control section. This indicates that the structural system or the support conditions can have an influence on the shear strength of wide members without shear reinforcement commonly neglected. In this paper, we investigate the influence of the structural system on the shear strength of wide members. For this purpose, we review the available test results that varied the structural system, and we compared the accuracy and precision level of shear strength models from the literature according to the structural system of the members. In the analyses, we observed that the ratio of tested to predicted shear capacity is 5 – 10 % smaller for cantilever members than for simply supported beams. On the other hand, the ratio of tested to predicted shear capacity is on average 10-20% larger in continuous members than in simply supported ones. Although these results may indicate some influence of the structural system in the shear behavior, in this study, we did not identify physical reasons to validate this hypothesis. In this way, this tendency of results could be addressed to some bias in the database. However, we verified that the correlation between the shear capacities of wide members could be better correlated with the shear slenderness by taking into account that the behavior of some continuous members under uniformly distributed loads is similar to the simply supported ones with a reduced span length.