Abstract:When encountering a catastrophic earthquake that exceeds the seismic fortification intensity of the region, the plate rubber bearing of the large-span space grid structure will produce a horizontal displacement exceeding the normal design range, resulting in ultra-low cycle fatigue damage. When encountering a disaster earthquake, in order to study the failure process and horizontal stiffness degradation of plate rubber bearings with large displacement in ultra-low cycle fatigue test, a test device capable of bidirectional loading was designed. Under different vertical forces, the complete plate rubber bearing with different diameter anchors was used to horizontally reciprocate, and the hysteresis curve, skeleton curve and horizontal stiffness degradation curve of the bearing were obtained and analyzed. The test results show that under the horizontal reciprocating loading, when the horizontal displacement of the plate rubber bearing exceeds the normal design range: ①The anchor bolt originally designed according to the structural requirements is involved in the stress, and the anchor bolt first suffered from fatigue fracture and became the weak link of the bearing; ②The horizontal stiffness of the bearing generally shows a process of increasing first and then decreasing; ③Increasing the diameter of the anchor can increase the horizontal stiffness and horizontal bearing capacity of the bearing, and the change in vertical force also has a certain degree of influence on the horizontal stiffness and horizontal bearing capacity of the bearing.