Finite Element Analysis of Double-Through Plate Joint

The common single plate shear joint is to weld a shear connecting steel plate directly on the surface of the steel pipe. This kind of joint connection often causes the stress concentration around the weld, and weld cracking is also a common failure mode of this kind of joint. To realize the fabricated shear connection between concrete-filled steel tubular column and steel box beam, a double-through plate joint was studied. In the joint, two shear connecting plates were parallel placed in the reserved slots on the two opposite walls of the steel tubular column, respectively. The part of the two through plates in the steel pipe was anchored by the filled concrete, and the plate's part outside the steel pipe was respectively close to the two webs of the steel box beam, which were connected with the beam webs by high-strength bolts. In this way, for the fabricated connection, there is no welding operation on the construction site, and the installation is simple and easy to operate. The finite element model of the joint was established, and the joint test results verified the effectiveness of the model. On this basis, the finite element method was used to optimize the design of the original test joint. Through detailed parameter analysis, the effects of initial gap between beam and column, thickness of through plate, bolt specification, bolt hole layout and other parameters on the joint performance such as stress distribution, deformation characteristics, bearing capacity, ductility and failure mode were studied.
The results show that compared with elliptical bolt holes and through core bolts, circular bolt holes and blind hole bolts are more conducive to improve the bearing capacity and ductility of the joint. With the increase of the initial gap between the end of the beam and the surface of the steel pipe, the through plate can full give play to its plastic deformation ability, and the rotation ability of the joint will be enhanced. However, when the gap is too large, the lower part of the plate is prone to buckling, which can lead to joint failure. Increasing the thickness of the plate can enhance the stability of the plate and improve the bearing capacity of the joint, but the thickness of the plate does not affect the angle of the end of the beam when it is extruded to the surface of the steel pipe. The influence of bolt specification on the overall bearing capacity and ductility of the joint is very small, but its influence on the failure mode of the joint is very obvious. When the bolt diameter is small, it is easy to shear failure. In terms of bolt layout, the excessive horizontal distance between the two bolt holes can not significantly improve the stress distribution. With the increase of the edge distance, the yield region of the plate is fully expanded, the plastic deformation ability of the through plate is enhanced, and ductility of the joint is significantly enhanced. It is suggested to use the layout of five or four holes in double or three rows instead of single row of bolt holes.