Numerical study of some post-cracking material parameters affecting nonlinear solutions in RC deep beams

Abstract

This paper describes a numerical study of some of the quasi-material parameters which are used to define the post-cracking response in smeared crack models for the nonlinear finite element analysis of reinforced concrete. The two major effects studied were interface shear transfer and tension stiffening. The investigation was carried out on a solid deep beam using a nonlinear plane stress formulation. Parabolic isoparametric elements were used with a standard nonlinear solution procedure.The effect of the quasi-material parameters was found to be significant in predicting the behaviour of the deep beam. A sudden drop in the stress at the cracking load was found to be important in the tension stiffening model. Different values can lead to different solutions for load–deflection curves, ultimate loads, and crack patterns. Also it was found that a large reduction in shear modulus to account for interface shear transfer can affect the nonlinear solution and cause numerical problems when used with a gradual release tension stiffening model with no discontinuity at the cracking load. Key words: deep beams, finite element, load deflection, post-cracking, shear transfer, tension stiffening, ultimate load.