Physically Based Cyclic Tensile Model for RC Membrane Elements

A physically based tensile model for RC membrane elements subjected to cyclic loading conditions is presented. Average concrete stresses are derived from equilibrium, compatibility, and constitutive relationships of a cracked RC element under biaxial stress-strain conditions. Cyclic bond degradation is explicitly accounted for in the equations governing tension-stiffening, crack-closing, and crack-opening. The proposed tensile model is combined with a compressive cyclic model to fully describe the axial response in the normal and parallel-to-the-crack directions. Along the crack, the constitutive model for shear is based on a new shear modulus, which allows divergence between principle stress and strain directions while satisfying equilibrium and compatibility conditions. The model is implemented within a fixed-crack membrane finite element and verified against experimental tests on shear panels and RC walls.