Material nonlinear analysis of steel fibre reinforced concrete beams failing in shear

Abstract

Experimental research has pointed out that fibre reinforcement gives valuable contribution for the shear strength of concrete beams. To obtain data to check the validity of the formulation proposed by RILEM TC 162-TDF for the evaluation of the fibres contribution for the concrete shear strength, sets of concrete beams were tested experimentally. To simulate the behaviour of this kind of structures, a computational code was developed, based on the finite element techniques. An accurate simulation of the behaviour of structures failing in a brittle mode, such is the case of the beams failing in shear, is a true challenge in the computational mechanics domain. To reproduce with enough accuracy the fracturing process of this type of elements, a multifixed crack model is implemented. The ability of the post-cracking stress-strain diagram proposed by RILEM TC 162-TDF to simulate the crack propagation is checked. A strain softening trilinear diagram is also derived from inverse analysis using the force-deflection relationship obtained in RILEM three-point notched beam tests. Its capability to model the fracture mode I is also assessed. The numerical strategy developed is described in the present work and the appropriateness of the model is evaluated simulating some beams tested experimentally.