The Analysis And Study Of The Ultimate Bearing Capacity Of Separation Concrete Filled Steel Tube Column Under Compression

In recent years, designing and building a lot of large span bridge structures with the rapid development of urbanization in China. Concrete filled steel tube column are widely used in the field of civil engineering by construction company because it has advantages such as resistance of compressive, resistance of seismic, resistance of refractory, resistance of corrosion, and economic. But for many of the concrete-filled steel tube arch bridge in the engineering. However, because of various factors the ability of concrete in the inside the rib of arch bonding with the wall of steel tube decreases and make them separate, which result in a phenomenon of separation which make resistance of whole concrete filled steel tubular column to compression decreases, it makes an obstacle to the development of the concrete filled steel tubular column. Therefore, the study of the mechanical performance of concrete filled steel tube column after separation has been focused on by an increasing number of experts in civil engineering field. In this paper, the ultimate bearing capacity of the concrete filled steel tube column after separation is analyzed in theory and simulated by the finite element software ANSYS, so as to explore ultimate bearing capacity of concrete filled steel tubular column after separation under both axial compression and eccentric compression compression.Through this article can gives some basic research materials about construction and safety testing of concrete filled steel tube column in the actual project.In this paper, the main work has been done:(1)The advantages and shortcomings of high strength concrete structure is introduced, when an earthquake occurs, the brittle failure of high strength concrete outside the high strength concrete columns will happen. Also introduce the advantages and mechanical characteristics of concrete filled steel tube structure, when the end of concrete-filled steel tube column under pressure, because steel pipe and concrete depend on and restrict by each other when they bear the pressure in common, this kind of composition structure made mechanics performance two kinds of material get used sufficiently. The advantage of concrete filled steel tube column in the field of bearing mechanical is that the steel tube under axial compression can produce ferrule effect to concrete, which make them be stressed in three directions. This is different from the uniaxial stress state of ordinary reinforced concrete under the axial compression and make the bearing capacity of each material get used sufficiently.But because of various factors concrete and inside wall of steel tube in the concrete filled steel tubular column are easy to escapes, this paper introduces the basic location, reason and test methods of separation. List the research status about concrete filled steel tubular column under both axial compression and eccentric compression.(2)The analysis and summary of existing research results, after quantities considerations of the rate of separation, get stress-strain curve of concrete in steel pipe; analysis of material nonlinearity, calculate geometric nonlinear by making it be equivalent to linear approximate, regard existing data as standard, using finite element software ANSYS to establish the concrete filled steel tubular column model under separation, the model are consistent to the selected specimens in size and material properties in the test, simulate the characteristics of columns in resistance to external load and the influence to ultimate bearing capacity by various parameters of columns eccentric compression, and gets some conclusions are helpful to the engineering practice, such as for the same concrete filled steel tube column with separation, the greater rate of separation, the lower bearing capacity of; Improve the strength of concrete and yield strength of steel both can increase the concrete-filled steel tube column to bear the axial load, improve the yield strength of steel is more obvious, but yield strength of steel is so big that it makes the cost of project high, it is also easy to result in brittle fracture of concrete filled steel tube column. Use calculation formula about stress of normal section of concrete filled steel tube structure, by the superposition method, make theoretical calculation to cross section of concrete filled steel tube column, list the results by formula compared with by the test and by ANSYS simulation, the error can satisfy the need of engineering practice.(3)Based on the limit equilibrium theory, the expression of the lateral pressure coefficient is obtained by linear regression. Derive formula of ultimate bearing capacity of concrete filled steel tube column with separation under axial pressure, and list the results compared with previous experimental, error can satisfy the need of engineering practice.