Modelo para calcular a contribuição da fibra na resistência à punção de lajes em concreto reforçado com fibra de aço Model to predict the contribution of fibre for the punching resistance of steel fibre reinforced concrete slabs

In this paper analytical formulations are developed for predicting the punching resistance of flat slabs of steel fiber reinforced concrete (SFRC) also flexurally reinforced with steel bars (usual reinforcement). By performing statistical analysis with a database that collects experimental results on the characterization of the post-cracking behavior of SFRC, equations are determined for evaluating the residual flexural tensile strength parameters ( fRi ) from fundamental data that characterize steel fibers. The fRi strength parameters proposed by ModelCode10 were used for the definition of the stress-crack width law ( �-w) that simulates the fiber-reinforcement mechanisms in cement-based materials. The second part of the paper describes an analytical formulation based on the concepts proposed by Muttoni and Ruiz, where the �-w law is conveniently integrated for simulation of the contribution of steel fibers for the punching resistance of SFRC slabs. By using a database composed of 154 punching tests with SFRC slabs, the good predictive performance of the developed proposal is demonstrated. The performance of this model is also evidenced by