Study On The Mechanical Behaviors Of The Hollow Reinforced Concrete Column Confined By GFRP Tube

The hollow reinforced concrete column confined by GFRP tube is a new type of member which combines the virtues of the concrete filled GFRP column and concrete filled hollow steel column. It is made of outer GFRP tube, inner PVC tube and reinforced concrete between them. GFRP tube can effectively resist the concrete and steel erosion from acid and alkali environment, restrain the concrete, improve concrete bearing performance and the members bearing capacity, and enhance the seismic ductility, etc. Compared with the solid column, this member is light-weight, so it can adapt to the contemporary engineering structures which have the requirement of large span, heavy load, durability, especially in the coastal complex environment. At present, scholars often focus on the solid concrete column confined by GFRP and the combined member with FRP concrete and steel tube, the research about this kind of member is rare. This paper analyzes the performance of the hollow reinforced concrete column confined by GFRP tube under centric axial loads by the test analysis and the finite element numerical simulation.Experimental research part designed six hollow reinforced concrete columns confined by GFRP tube with different hollow ratio and different reinforcement ratio. Through axial compression test, observed the test phenomenon, the failure pattern, the load-strain curves, the load-displacement curves, the ultimate bearing capacity, and analyzed the influence with different parameters. With the increase of hollow ratio, the confinement effect by the GFRP tube on the core concrete is reduced, but not linear relationship. With the increase of the reinforcement ratio, the bearing capacity is nonlinear improvement. In addition, the confinement effect by the GFRP tube is increased firstly and then decreased.Numerical analysis use the finite element software ANSYS. Analysis results coincides well with the experiment results. Then, research the mechanical behaviors of the hollow reinforced concrete column confined by GFRP tube under the different influence parameters. Parameters include hollow ratio, reinforcement ratio, concrete strength and slenderness ratio. Simulation results were basically same to test results with different hollow ratios and reinforcement ratios. With the improvement of the concrete strength, the bearing capacity was better, however, the confinement effect by the GFRP tube on the core concrete is reduced. With the increase of slenderness ratio, the bearing capacity of the composite column reduced. The decline was slow at the beginning, and the column was destroyed with the material breakage. The decreasing amplitude developed fast after a certain slenderness ratio, and the column was destroyed because of instability.