Improved plastic-damage cap model for shear behavior predictions of plain and reinforced concrete members

Abstract

In this article, an improved continuous surface cap model (ICSC) with isotropic plastic-damage algorithms is proposed, namely to predict more accurately the shear behavior of both plain and reinforced concrete members. For this, a suitable yield surface is implemented and the critical shear-to-compression transition parameter in the ductile damage law is scrutinized and determined. Firstly, the mathematical framework of the plastic-damage cap model is summarized, namely the formulations in plasticity, the returning mapping algorithms of cutting plane and the isotropic damage law. Then, the proposed constitutive parameters in ICSC model are presented. The plastic-damage algorithms flowchart is presented and described, and the new proposed ICSC model is implemented in the software LS-DYNA. Next, the proposed ICSC model is validated against the original CSC model (MAT159 in LS-DYNA) and also against the previously improved CSC model with crack closure behavior developed by the authors. For this, several simulations using the three CSC models are performed and the results are compared with experimental results, which involve single concrete element under various loading conditions, plain concrete structure under direct shear load and simply supported reinforced concrete (RC) beams with or without stirrups under a center-point load. The results are presented and discussed. They show the superiority of the proposed ICSC model for the prediction of the ultimate concrete behavior at the material level, and a better prediction of the shear behavior for plain concrete and reinforced concrete beams.