Experimental study on seismic property of concrete filled FRP-steel tube

The same size specimens strengthened by FRP(CFRP/GFRP) sheets with different wrapping modes were studied experimentally by quasi-static test system for the purpose of investigating the mechanical property of concrete filled GFRP-steel tube structure under combined seismic loading and comparing it with concrete filled CFRP steel tube. Combined loads including axial pressure and bending were applied to simulate the complex seismic loadings. The test results indicate that the strengthening of FRP(CFRP/GFRP) is potential and effective for significant improvements in dynamic bending resistance of the structures. Concrete filled GFRP-steel tube equips higher ductility, comparing with concrete filled steel tube, energy dissipation coefficient of the components with circumferential, longitudinal and bi-directional GFRP improve 2.0%, 7.0% and 12.7% respectively, while components with circumferential, longitudinal and bi-directional CFRP get improvement of 2.0%, 5.8% and 6.7% respectively.