Finite Element Analysis On Mechanical Properties Of Circular Concrete Filled Steel Tubular Column To Steel Beam Connections

Beam-column joint is a key part of building structures, so it significantly affects mechanical performance of structures. At present, research on concrete filled steel tubular structures is rapidly developing. However, theoretical study on circular concrete filled steel tubular column to beam connections is not enough. Therefore, it has important theoretical meaning and engineering application value to carry out research on seismic performance of circular concrete filled steel tubular column to steel beam connections.By using FEM software ANSYS, Reinforced loop joint, continuous web plate joint and hinged joint performance of concrete filled circular steel tubular column to steel beam under the monotonic loading and cyclic loading are studied.Analysis under the monotonic loading shows that: (1) Continuous web plate joint has good mechanical properties; its bearing capacity is the maximum, reinforced loop joint's bearing capacity is next maximum, and hinged joint's bearing capacity is the minimum in the same of member's size, type of concrete and steel. (2) It is known that above-mentioned three types of joints have good ductility from the load-displacement curve. (3) Local buckling is occurred on the flange of connected beam of three types of joints.Stress distribution, hysteretic behavior and energy dissipation capacity of three types of joints under cyclic loading are studied. The results show that (1) Rigid joints (reinforced loop joint and continuous web plate joint) have stable hysteretic characteristic and enough energy dissipation capacity. (2) Compared with rigid joints, hysteretic characteristic of hinged joint is not so stable.Based on the analysis of existing joints, a new type of joint is put forward in this paper. Its mechanical performance is compared with above-mentioned three types of joints. The influence of material type and axial compression ratio on seismic performance of new joint is analyzed. The results show that: (1) New joint has greater bearing capacity, more stable hysteretic curve, better energy dissipation capacity and ductility. (2) New joint's bearing capacity slightly increases when concrete strength increases. However, hysteretic energy dissipation capacity shows increasing trend. The grade of steel has great influence on the performance of new joint. The bearing capacity and stiffness of new joint increase when steel strength increases, hysteretic energy dissipation capacity decreases. (3) When axial compression ratio is small, the ductility of the joint increased. However, with the increase of axial compression ratio, the peak load decline, hysteretic behavior and energy dissipation capacity decrease.