Abstract
Various constitutive models are used in the nonlinear finite element (FE) analysis of reinforced concrete (RC) structures. Several researchers still utilize the Drucker-Prager model in conjunction with the tension cut-off to predict the reaction of reinforced concrete in structures such beams, beam-column joints, and slabs, despite the fact that concrete response models have progressed significantly. To accurately capture the non-linear behavior of RC members using the Drucker Prager model cohesion factor "c" and angle of friction "phi" plays an important role. This paper addresses the issue of how to select appropriate values for the angle of internal friction "phi" and a consistent cohesion factor "phi" in the Drucker-Prager or the Mohr-Coulomb elastoplastic constitutive models in nonlinear finite element modeling to investigate the behavior of reinforced concrete structures. Literature shows a big variation in the selection of "phi", from 10 degrees to almost 60 degrees, obtained by calibrating the results of the numerical model to experimentally observed data. In this paper, using theoretical concepts, it is shown that different values of "phi" and "c" can be obtained, depending on whether the two parameters involved are calibrated to data involving, two at a time, of the three easily available experimental measures i.e. uniaxial compressive strength, f(c)', uniaxial tensile strength, f(t), and biaxial compressive strength, f(bc)'. The concepts are further strengthened by comparing numerical results to experimental results for studies conducted on flexure-reinforced concrete beams and external beam-column joints in different research centers worldwide.