Cracking and hysteretic behavior of reinforced concrete shear walls

Abstract

This thesis presents an analytical model to simulate the nonlinear hysteretic behavior of reinforced concrete (RC) structures subject to general in-plane stresses. The material behavior of concrete is described by an orthotropic constitutive relation, focusing on the tension-compression region with tension-stiffening and compression softening effects defining the equivalent uniaxial stress-strain relation in the axes of orthotropy. The behavior of cracked concrete is described by a system of orthogonal cracks, which follows the principal strain directions and rotates according to the loading history. From the strain distribution of concrete, energy equilibrium condition and average stress-strain concept, a cracking model for reinforced concrete planar structures to predict the post-cracking behavior of tension governing structures is introduced. Based on the force equilibrium, compatibility condition, and bond stress-slip relationship between the reinforcement and the surrounding concrete, a tension stiffening model that can simulate the rotation of crack angle and the interaction between reinforcing steel and concrete for shear dominated structures is proposed using the concept of average stresses and strains. In addition, an interface element is used to account for local discontinuous deformations at the boundary plane where members with different thicknesses are connected. While maintaining all the basic assumptions adopted in defining the constitutive relations of concrete under monotonic loadings, a hysteretic stress-strain relation of concrete, which crosses the tension-compression region, is defined. In addition, unlike previous simplified hysteretic stress-strain relations, curved unloading and reloading branches inferred from the stress-strain relation of steel considering the Bauschinger effect are used. Modifications of the stress-strain relation of steel are also introduced to reflect pinching and buckling effects depending on the shear span ratio a...