An enhanced damage plasticity model for predicting the cyclic behavior of plain concrete under multiaxial loading conditions

Some of the current concrete damage plasticity models in the literature employ a single damage variable for both the tension and compression regimes, while a few more advanced models employ two damage variables. Models with a single variable have an inherent difficulty in accounting for the damage accrued due to tensile and compressive actions in appropriately different manners, and their mutual dependencies. In the current models that adopt two damage variables, the independence of these damage variables during cyclic loading results in the failure to capture the effects of tensile damage on the compressive behavior of concrete and vice-versa. This study presents a cyclic model established by extending an existing monotonic constitutive model. The model describes the cyclic behavior of concrete under multiaxial loading conditions and considers the influence of tensile/compressive damage on the compressive/tensile response. The proposed model, dubbed the enhanced concrete damage plasticity model (ECDPM), is an extension of an existing model that combines the theories of classical plasticity and continuum damage mechanics. Unlike most prior studies on models in the same category, the performance of the proposed ECDPM is evaluated using experimental data on concrete specimens at the material level obtained under cyclic multiaxial loading conditions including uniaxial tension and confined compression. The performance of the model is observed to be satisfactory. Furthermore, the superiority of ECDPM over three previously proposed constitutive models is demonstrated through comparisons with the results of a uniaxial tension-compression test and a virtual test.

Finite element simulation of a motorway bridge collapse using the concrete damage plasticity model

The aim of this work is to show how the concrete damage plasticity model developed by Lubliner et al. can be applied for calculation of a motorway bridge collapse occurred in the Amur region, Russia. The concrete structural behaviour is highly complex. Being a quasi-brittle material, concrete demonstrates softening behaviour that is numerically complex due to the loss of positive definiteness of the tangent rigidity matrix of the material, and hence the loss of the ellipticity of the equilibrium rate equation. This eventually leads to the loss of well-posedness of the rate boundary value problem. Besides that, concrete behaviour in compression differs from that in tension. There are a few different failure modes of concrete material: tension cracking, compression crushing, spalling of concrete, etc.