Strength Concrete Core Column Under Axial Compression Theoretical Research

With the development of the high-rise building in our country, steel reinforced concrete (SRC) are researched and implemented comprehensively. As a kind of SRC, the high-strength concrete filled steel tube reinforced concrete (CFSTRC), which shows an alluring applying prospect, is endowed with better mechanical property than the common SRC structure, due to the confined concrete by steel tube. However, due to the little systematical research on the CFSTRC, and it is unfavorable for application and development of this kind of component.Firstly, this paper summarizes the limited load-carrying capacity formula of the Composite Column with Core of High-strength Concrete filled Circular Steel Tube which under axial pressing. Then, based on the testing datum, this paper proposes normal section load-carrying capacity formula of CFSTRC. Compare results of the formula with test results, they inosculate well. This indicates that the formula proposed in this paper has certain dependability.And the nonlinear FEM analysis about axial pressing and small eccentricity pressing of CFSTRC, the next part of this paper, is conducted to observe the influence of sector factors to limited load-carrying capacity such as steel tube ratio, volumetric percentage of stirrups and reinforced bar-diameter. No matter axial pressing or small eccentricity pressing of CFSTRC, it can be concluded such conclusions as following. (1)Compared with normal concrete filled steel tube (CFST), the CFSTRC has better ductibility and limited load-carrying capacity. The outer reinforced concrete offers much help to yield load and limited load. (2) Under the same situation as tube-diameter and so on, yield load and limited load increase with the increasing of steel tube ratio. But the steel tube ratio's variety has ruleless to maximum displacement of the upper column. (3) Under the same situation as steel tube ratio and so on, yield load and limited load increase with the increasing of volumetric percentage of stirrups. The stirrups's restriction offer much help to delaying the outer concrete's breakage. (4) Under the same situation as steel tube ratio and volumetric percentage of stirrups and so on, yield load and increases with the increasing of reinforced bar-diameter. But the variety of reinforced bar-diameter has ruleless to limited load and ductibility. (5) When CFSTRC is fail to bear loads, protection cover's concrete and outer concrete reach axial compressive strength firstly, then core concrete, steel tube is the last.