Study on the Performance Degradation of LRB Under the Combination of Low Temperature Cycles and Superstructure Weight

Abstract

ABSTRACT Lead rubber bearing (LRB) may be subjected to low temperature effect and superstructure weight when it was used in the cold regions, which will affect the durability of the bearing. To investigate the performance degradation of the LRB under combination of low temperature cycles and superstructure weight, five specimens were designed to conduct 0, 20, 40, 60, 80, and 100 low temperature cycles while maintaining super load of 0, 4, 7, 10, and 12 MPa. The use of ultra low temperature and ordinary temperature room to simulate the environment of low temperature effect and the specimen was kept under compression to simulate superstructure weight. The degradation of the mechanical properties of LRB was analyzed by conducting vertical compression tests and horizontal shear tests on the specimens. The results show that the vertical compression stiffness, equivalent horizontal stiffness, post-yield stiffness, yield force, and equivalent damping ratio of LRB show a decreasing trend under the low temperature cycles and superstructure weight. With the increase of superstructure weight, the degradation of equivalent horizontal stiffness is aggravated, the equivalent damping ratio does not degenerate, and the degradation of post-yield stiffness and yield force is weakened. Finally, the least squares method is used to analyze the change of its horizontal shear performance and give the degeneration curve and degeneration function for 50 years. The degradation curve of the horizontal shear performance of LRB is basically in the form of an exponential function.