Experimental Investigation On New Type Joints Of Outer-plated Steel-concrete Composite Beam-column

The outer-plated steel-concrete composite beam is a new type of composite beam, which evolved from the steel-concrete composite beam, and compared with general composite beam this new type composite beam possesses having the merits of steel-saving, good stability, high load-bearing capacity and high stiffness. Based on the joint connecting of concrete-filled steel tubes column and steel beam and concrete-filled steel tubes column and reinforced concrete beam, this research presents two new types joints connecting of concrete-filled steel tubes column and outer-plated steel-concrete composite beam ,and two new type joints connecting of reinforce concrete column and outer-plated steel-concrete composite beam. The accomplished primary works and obtained achievements include:(1)The low-cycle repeated load tests are conducted for both two new types' joints connecting of concrete-filled steel tubes column and outer-plated steel-concrete composite beam. And investigate the ductility and energy dissipation of both the two new types' joints, and measured the strain of bottom plate, steel bars and core area of joints. The test results show that the failure of both the two new type joints started from beam end and the core area of joints do not yielding. The hysteretic curves possesses shrinking phenomenon and the shearing deformation in joints core area are very small. The deflection of beam end is mainly composed of bending deformation. Both the two new type joint have favorable ductility and energy dissipation and the seismic behavior are very well.The theory of material mechanics and concrete struts are applied for calculating the shear capacity of steel tube, steel and concrete. And the total bearing capacity is adding the bearing capacity of tube and concrete. There are difference between experimental results and theory results. The difference is caused by test device. This paper presents design suggestion of the new joints according to failure mode.(2) The low-cycle repeated load tests are conducted for both two new types' joints connecting of reinforce concrete column and outer-plated steel-concrete composite beam. And investigate the ductility and energy dissipation of both the two new types' joints, and measured the strain of bottom plate, steel bars and core area of joints. The result of the experiment indicates that significant shear-resistant capacity and satisfactory energy dissipation ability can be obtained by appropriate constructional measure so as to satisfy the engineering requirement. Based on the analysis of test, the force mechanism of joints is investigated and the formula for calculating the shear capacity of the joint is presented.