Research On The Mechanical Performance Of Self-locking Joints Of Wheel-coupler Type Formwork Support

In recent years,with the vigorous development of the construction industry,high-rise,super high-rise and large-span buildings are emerging.As an indispensable temporary structure in the construction process,scaffold needs to be continuously reformed and updated.The wheel-coupler type formwork support is a new type of scaffold,which has a short application time in China,the research on it is still in the start stage and has not yet formed a unified standard.At present,only some Association Standards and Local Standards are used as references,and the relevant theoretical research is still not perfect,which seriously restricts its promotion and use.This paper conducts related researches on the mechanical properties of wheel-coupler joint node.Firstly,using statics analysis and fracture mechanics theory to analyze the stability of the mechanical connection and weld connection of the node,it is found that the node will self-lock when subjected to force,and the initial crack half width of the weld should be less than the critical value.Determine the node connection is safe and reliable.And by adjusting the basic assumptions and parameters of the modeling,the setting method of the finite element analysis of the wheel-coupler joint node is determined,and the results obtained by the finite element are compared with the experimental results to verify the reliability of the finite element model.Secondly,the interference contact analysis was carried out by using ANSYS finite element software,and the minimum wedge depth,normal wedge depth and maximum wedge depth of the joint were determined.Thus,the finite element models of shear,tension and compression of the joint under different loading forms were established,and the load-displacement curve,stress distribution state and the expansion process of plastic strain zone of the joint were obtained.The force transmission path,bearing capacity and failure mode of the joint were clarified.It was found that the joint had nonlinear characteristics under stress,and the bearing capacity of the joint was related to the load mode.The bearing capacity was higher under biaxial symmetric tension or compression,and the failure mode could better reflect the stress failure at the joint.Finally,ANSYS finite element software was used to simulate and analyze the tensionbending,bending-torsion,and tension-bending-torsion models of joints under different wedge depths.The load-displacement curve,stress distribution state,and the expansion process of plastic strain zone of the joints were obtained,and the failure mode,bearing capacity,and rotational stiffness at different stress stages of the joints were clarified.Combined with European specification 3,the semi-rigid characteristics of the wheel-coupler joint node were determined.It was found that the wedge depth had little effect on the bending strength of the joints,and had great effect on the initial rotational stiffness of the joints.The initial rotational stiffness of the joint is as follows: Tension-bending > Tension-bending-torsion > Bendingtorsion.