A Study on the Effect of Diagonal Cracks Opening on the Failure Behavior of RC Beam-Column Joint With Mechanical Anchorages by 3D RBSM

Abstract

Local reinforcement along the anchorages can be one way to avoid anchorage failure in the beam-column joints with mechanical anchorages. However, previous experimental work showed that different macroscopic behaviors were observed with different local reinforcement arrangements. The reason for such variations was not clarified since internal stresses and internal crack conditions are not well understood. It is considered that the opening of diagonal cracks in the beam-column joint plays an important role on the failure behavior. In this study, a meso-scale discrete analysis using 3D rigid body spring model (RBSM) is conducted to investigate this consideration. Parametric studies by 3D RBSM are conducted in which stirrups along the anchorages in the joint are modeled as deformed and plain bars. Based on the simulation results, different performances are predicted with different types of stirrups. Before the occurrence of diagonal cracks, bond performance along the development length of the anchorages depends on the number of stirrup and is not affected by the type of stirrup. Once diagonal cracks occur, the opening of diagonal cracks is affected by the type of stirrup. When stirrups are modeled as plain bars, slippage occurs easily between concrete and reinforcement and diagonal cracks then open readily. Furthermore, damage occurs at the top surface of the joint, leading to a decrease in capacity.