Exterior Concrete Beam-column Connection Reinforced with Glass Fiber Reinforced Polymers (GFRP) bars under Cyclic Loading

This paper is devoted to assess the behavior of the exterior concrete beam-column connections reinforced with Glass Fiber Reinforced Polymers (GFRP) bars under cyclic loading. For this purpose, 8 different beam-column connections were experimentally investigated. In these specimens, concrete with compressive strength of 30 and 45 MPa was employed. In four of these connections, GFRP bars were used while the others were reinforced with steel bars. The confinement of longitudinal bars was different in the connections. The GFRP-reinforced beam-column connection showed an elastic behavior with very low plasticity features under cyclic loading. This resulted in lower energy dissipation compared to the steel-reinforced beam-column connections. The GFRP-reinforced beam-column connections showed lower stiffness than that of the steel-reinforced beam-column connections. Load-story drift envelope for specimens with GFRP bars showed an acceptable drift capacity. These specimens had the essential requirements for acting as a member of a moment frame in seismic regions. In case of GFRP strengthened specimens with low and high strength concrete, increasing the cyclic loading results in flexural failure of the beam in the beam-column connection region. Increasing the confinement of concrete beams leads to the reduction of crack width. Furthermore, at higher drifts, spalling was not observed in concrete surface in beam-column connection region. In the analytical parts of the study, specimens were simulated using the SeismoStruct software. Experimental and analytical results showed a satisfactory correlation.