Influence of freeze-thaw cycles and aging on the horizontal mechanical properties of high damping rubber bearings

Freeze-thaw cycles, aging, and freeze-thaw cycles superimposed aging test on high-damping rubber bearings (HDR) were performed to study the durability of HDR for sea-crossing bridges in northern coastal areas. The change laws of horizontal mechanical properties of HDR under different tests were revealed. After freeze-thaw cycles, the equivalent damping ratio and yield force of HDR decreased, the post-yield stiffness increased slightly, but the horizontal equivalent stiffness wasn't change; The ultimate shear force and displacement of HDR abated. Under aging test, horizontal equivalent stiffness and post-yield stiffness increased significantly, and the change of its yield force could be ignored, while the equivalent damping ratio decreased. The horizontal equivalent stiffness and post-yield stiffness of HDR increased; however, the equivalent damping ratio and yield force decreased after the freeze-thaw cycles superimposed aging test. Besides, experimental results indicated considering freeze-thaw cycles or aging alone cannot accurately estimate the change of HDR's performances in the actual environment. This study is likely to provide a whole life cycle design and evaluation basis for coastal seismically isolated bridges with HDR in the cold regions of northern China.