A practical plasticity-damage concrete model for simulating axial–shear–flexure interaction of RC structures

Purpose It is of significant importance to predict the earthquake-induced damage of reinforced concrete (RC) structures. However, a practical concrete model is still urgently desired that is accurate, efficient and stable for simulating axial–shear–flexure interaction of RC structures. Design/methodology/approach In this paper, a novel plasticity-damage concrete model is presented where three conceptually independent yield surfaces are defined that keep updated with combined damages of tension, compression and shear directions. When combined with the Timoshenko fiber frame element, the model is able to efficiently and accurately simulate the strength decreasing, stiffness deterioration and pinching effects related to accumulated damage. More importantly, the model exhibits excellent stability by guaranteeing the stress to be continuous with strain, i.e. no stress jump occurs when strain passes through different yield surfaces or when the yield surface shrinks due to damage increases. Findings Two numerical examples of RC frames with flexural and shear failures, respectively, are analyzed and compared with experimental results. Originality/value The model is demonstrated to be able to simulate complicated axial–shear damages of RC frame structures.