Study On Concrete-filled FRP Tube Composite Column

Steel-FRP composite concrete steel columns is placed in the FRP tube, then pouring concrete composite structure. it is High strength for the steel is built-in and FRP pipe is corrosion resistance, so it can be used in serious corrosion condition, resistance to harsh environment (humidity, corrosion, freezing, etc.) and can effectively improve the durability of concrete, prevent carbonation of concrete and steel corrosion. The birth of this new composite structure has been studied by domestic and foreign scholars extensively. this paper is study on 12 groups combination of steel reinforced concrete-FRP specimen and analysis the axial compression mechanical properties for different steel ratio, concrete strength grade and thickness of the specimen.Steel-FRP pipe concrete under axial compression test results show that High rates of steel specimens the capacity is high, Load displacement curve is stable, the bearing capacity of specimens are stable when the ratio of steel in cross-section is high. Ductility and post-load capacity is relatively good. FRP pipe to the concrete.Constraints effect is reduced accompany with the Increase in concrete strength ,mainly due to lateral deformation of high-concrete is small, Resulting in a binding effect relatively lower. When the thickness of steel-FRP pipe wall of concrete structures is not at the same level, the bearing capacity of GFRP specimens increased accompany with wall thickness increased, Strain yield changed little corresponding with the two samples yield point, This is due to constraint effect of GFRP tube on steel is not obvious. After the steel yield, Strain developed rapidly.Through the test data and the existing steel-FRP pipe concrete strength formulation, proposed two composite short columns bearing capacity formulation that is uniform law and superposition method. The average of the two methods were 1.046 and 1.047 respectively, the results are in good agreement.