NLFM for FRC Pavement Analysis and Design

Abstract

Non Linear Fracture Mechanics (NLFM) represents a powerful tool for analyzing Fiber Reinforced Concrete (FRC) slabs on grade; in fact, because of the stress redistribution, possible in these statically indeterminate structures, the bearing capacity can remarkably increase after reaching the ultimate strain up the formation of a collapse mechanism. This evidences that slab behavior is highly influenced by the crack propagation and underlies the importance of a fiber reinforcement. In fact, concrete roughness is significantly increased by steel fibers that may substitute (partially or totally) conventional reinforcement. Fibers also increase the crack resistance of concrete pavement. The use of a NFLM method for modeling concrete slab on grade with different types of reinforcement is presented in this paper. The validation of the methods was firstly obtained by simulating experiments on full-scale slabs subjected to different loading conditions. The numerical analyses proved to be in a good agreement with the experimental response for the load-displacement behavior, for the ultimate load and for the final crack pattern. Finally, some deign considerations are introduced by comparing the numerical response or slabs characterized by the same geometry and loading conditions and a different reinforcement arrangement. In particular, the behavior of concrete slabs reinforced by steel fibers only, by steel rebars only or by steel rebars and fibers together is presented.