Behavior of Unbonded, Post- Tensioned, Precast Concrete Connections with Different Percentages of Mild Steel Reinforcement

Abstract

This paper presents the results of tests performed on post-tensioned, precast concrete moment-resisting, beam-column connections containing different mild steel reinforcement contents. In the experimental program, five hybrid connections were tested under displacement-controlled reversed cyclic loading. The main variable was the mild steel's percentage of contribution to the flexural capacity of the connection, ranging from 0% to 65% of the connection's moment capacity. Each hybrid connection was compared with the test result of the reference monolithic subassembly in terms of connection strength, stiffness degradation, energy dissipation, and permanent displacement. The objective of this study was to determine the effect of mild steel reinforcement content on the behavior and performance of post-tensioned, precast concrete hybrid connections. The response of post-tensioned, precast concrete hybrid connections approached that of the monolithic subassembly as the mild steel reinforcement content increased. Connection capacities were well predicted by the joint gap-opening approach. The design assumptions of hybrid connections are best satisfied with a 30% mild steel reinforcement contribution to the connection's flexural capacity.