Mechanical Behaviors Study Of Steel Tube Filled With Steel-Reinforced High-Strength Concrete

With the rapid development of urban areas and frequent occurrences of natural disasters, people nowadays show a rising demand for the function of super high-building with big space as well as the security of constructional structure. Through investigating the damages caused by earthquakes, people have realized the design of columns plays a key role in preventing the collapse of buildings in strong earthquakes. Steel tube structure filled with steel-reinforced concrete has the advantages of concrete filled steel tube structure and steel reinforced concrete construction. Be of a good mechanical function, it answers to the need of big-span, high-rise and heavy load in modern engineering structure. Based on experiments and theoretical analysis, the mechanical properties of high-strength concrete-filled circular steel tube members into which I-shaped steel section is inserted are researched. The major contents are summarized as follows:Based on steel and modificatory constitutive relationship of concrete, the calculation procedure of steel tube columns filled with steel-reinforced high-strength concrete under axial compressive is compiled. The effects of confining index and steel-reinforced index on the stress-strain curves are discussed. In order to promote engineering applications, basing on uniform theory, ultimate balance theory and experience coefficient method, formulas used for predicting the ultimate bearing capacity of the composite column are proposed and effective methods to improve the bearing capacity under axial compressive are analyzed.Base on the study of eccentric compressive experiments, the working mechanism and failure mode are analyzed, and the effects of eccentric moment, slender ratio and loading direction on the bearing capacity, deformation and confining force are discussed. With fiber model method, the nonlinear procedure of steel tube columns filled with steel-reinforcement high-concrete under eccentric compression are developed, and the effects of main parameters on the load-deformation curves are discussed. Using the method of ultimate balance and experience coefficient, the formulas of ultimate bearing capacity of steel tube columns filled with steel-reinforcement high-concrete under eccentric compression are given.Base on the study of pure bending experiments, the working mechanism and failure mode are analyzed, and the effects of steel-reinforced index and loading direction on the bearing capacity, deformation and confining force are discussed. With fiber model method, the nonlinear procedure of steel tube columns filled with steel-reinforcement high-concrete under pure bending compression are developed. Using ultimate balance theory, ultimate bearing capacities of pure-bending components under different failure models are given. On the foundation of uniform theory, the formulas of ultimate bearing capacities of pure-bending components are worked out.Base on the study of compression and bending experiments, the working mechanism and failure models are analyzed, and the axial compression ratio, loading direction and loading manners on the bearing capacity, deformation and confining force are discussed. On the foundation of uniform theory, the simple formulas of ultimate bearing capacities of compression and bending moment by N-M relationship method are worked out.Through numerical calculating, the dynamical performances of steel tube components filled with steel-reinforcement high-concrete are analyzed and the program for dynamical analysis is established. The main factors of feature, slenderness ratio,steel-reinforced index and grade of concrete affected on vibration mode are analyzed.