Effect of Stirrups on Lateral Cyclic Behavior of Interior Glass Fiber-Reinforced Polymer-Reinforced Concrete Slab-Column Connections

摘要

Providing shear reinforcement around slab-column connections in flat-plate structures located in seismic zones has proved to be effective in enhancing the punching shear performance of slabs. It results in increased punching shear strength, lateral-drift capacity, and ductility factor, while reducing connection stiffness deterioration. This paper presents the first-ever experimental investigation on five full-scale concrete slab-column connections reinforced with glass fiber-reinforced-polymer (GFRP) bars and stirrups. Each slab measured 2500 ⅹ 2500 mm with a thickness of 200 mm, and 300 mm square column extending 700 mm above and below the slab surfaces. All specimens were tested to failure under the combination of gravity and lateral reversed cyclic loading. The experimental study aimed to evaluate the effects of stirrups type (closed and spiral), stirrup extension, and gravity-load intensity on the seismic behavior of the connections. The test results showed that using GFRP stirrups around the slab-column connection significantly enhanced the seismic performance of the connection. The slabs with GFRP stirrups exhibited punching-shear failure with a gradual decrease in lateral load and maintained their integrity. Slabs reinforced with GFRP stirrups achieved lateral inter-story-drift capacity exceeding 2.5%, satisfying the limits in CSA A23.3 andACI421.2R. Moreover, all shear-reinforced slabs demonstrated high lateral-ductility indexes which are higher than the minimum ductility factor of 1.2 for steel-RC slab-column connections. Additionally, slabs with GFRP stirrups displayed an excellent ability to dissipate energy during high lateral-drift levels.