Seismic behavior and restoring force model of GFRP-RC beam-column interior joints

In this paper, the beams-column interior joint in the concrete frame structure was taken as the main research object. First, four joints reinforced with GFRP (glass fiber reinforced plastic) bars were used to analyze the influences of reinforcement ratios under reversal cyclic loading. Then, the failure mechanism of the joints with GFRP bars was analyzed based on the damage of concrete and the bars. Finally, the corresponding restoring force model was proposed to show the bearing capacity and deformation characteristics of joints. The results show that the seismic behaviors of the GFRP-RC (glass FRP reinforced concrete) joints are good due to the high drift ratio, which can reach to about 6%. The energy dissipation of the joints mainly comes from the compression damage of the concrete. Compared with steel reinforced concrete, the high ultimate drift rate increases the range of concrete involved in energy consumption, which makes up for low energy consumption of GFRP bars. The stiffness degradation of the skeleton curve is related with the damage of concrete and the surface damage of the reinforcement. Besides, the damage of the bars was concentrated on the surface of the rib marks. The four-stage hysteretic model proposed in this paper can better reflect the seismic behaviors of joints. This study aims to provide research basis for the researches of GFRP-RC structures from the component level to the structural level.