Effect of GFRP Shear Stirrups on Strength of Two-Way GFRP RC Edge Slabs: Experimental and Finite-Element Investigations

Abstract

Glass-fiber-reinforced-polymer (GFRP) reinforcing bars have recently gained wide acceptance as a viable construction material for sustainable new constructions. Yet current codes and guidelines have not addressed the design of GFRP-reinforced-concrete edge-slab–column connections with FRP stirrups as shear reinforcement. This paper summarizes the experimental results for full-sized edge-slab–column connections reinforced with GFRP bars and stirrups. The effectiveness of the GFRP stirrups and their extension from the column face on the performance of the tested connections are examined. In addition, a nonlinear three-dimensional (3D) finite-element analysis (FEA) is used to perform an in-depth investigation. Then, a comprehensive parametric investigation is presented on edge connections with different stirrup sizes, extensions located at different distances from the column, and different spacings. The test results reveal that the presence of GFRP stirrups as a shear reinforcement in the slab around the column perimeter improved the punching-shear response. In addition, the FEA results are in good agreement with the experimental results in terms of ultimate load, cracking patterns, strains in the reinforcement and concrete, and load-deflection relationships, thereby confirming the accuracy of the finite-element model. The results confirm that the punching-shear resistance decreased with increasing stirrup spacing and increased with increasing stirrup size and extension from the column. Based on the numerical-simulation results, a simple design approach to predicate the ultimate capacity of the tested connections is proposed. The model yielded good yet conservative predictions with respect to the experimental results as well as the available results in the literature.