Displacement Capacity of Shear-Dominated Reinforced Concrete Walls

In this paper the load-displacement response and displacement capacity of shear-dominated reinforced concrete walls is studied with the help of a three-parameter kinematic theory (3PKT). The 3PKT is a rational and efficient approach based on a three-degree-of-freedom kinematic description of the deformation patterns in cantilever walls with aspect ratios ≤3.0. In addition to kinematics, the 3PKT also includes equations for equilibrium and constitutive relationships for the load-bearing mechanisms in walls. The paper summarizes this approach and applies it to nine wall tests from the literature featuring a wide range of test variables. It is shown that the model captures adequately the response of both moderately short walls (aspect ratios 2.2-3.0) and squat walls (ratios 0.33-0.54). With the help of the load-bearing mechanisms predicted by the 3PKT, it is shown that shear failures in squat walls develop due to the complex interaction between concrete crushing in the toes of the walls and aggregate interlocking along flat critical cracks. A modification to the 3PKT is proposed to capture the effect of loading conditions on squat shear walls. With this modification, it is shown that the 3PKT can also capture the effect of concrete stiffness, concrete compressive strength, and reinforcement ratios on the shear response of squat members. For all tests considered in this study, the 3PKT produced an average shear strength experimental-to-predicted ratio of 1.05 and a coefficient of variation COV=10.5%. Similarly accurate predictions were obtained for the displacement capacity of the walls: an average of 0.90 and COV=15.69%.