Experimental study on friction properties and optimization of U-shape steel support joints

The friction performance of U-shape steel support joints is one of the important factors that affect the support performance. Under the impact ground pressure loading,the friction relationship between the U-shape steel and the ca-ble is often poor,which leads to the failure of the U-shape steel bracket to reach the theoretical bearing capacity,and the structural instability and failure of the support will occur. The friction properties of different materials are tested by the self-made device for testing friction performance,and the friction force and the change law of friction coefficient in the sliding process of steel plate and steel plate,steel plate and soft metal plate,steel plate and rubber plate under dif-ferent pre-tightening torque conditions are obtained. The results show that under axial pressure the frictional force be-tween steel and steel will decrease suddenly after reaching the maximum static frictional force,resulting in a sudden drop of bearing capacity at the joint,which is not conducive to the stability of the support. When the steel and soft metal slide,the bearing capacity changes more smoothly. When the sliding occurs between steel and rubber,the frictional force decreases and fluctuates with the increase of sliding distance. The friction coefficient between steel and soft metal is greater than that between steel and steel,steel and rubber plate. Under the condition of the same relative sliding dis-placement between contact surfaces,more energy is absorbed at the joints. The above research indicates that the soft metal plate is placed at the joint of the O-shape shed support joint,which can effectively improve the friction properties at the joint and improve the bearing capacity and the impact resistance of the U-shape steel support.