Analysis of general functional bearing model in a single-span bridge to identify structure response and suitable friction coefficient under near- and far-fault earthquakes

Analysis of a single-span bridge with rubber bearing as the isolation system is performed under earthquakes. The conventional bridge seismic design requires the whole structure to be perfectly connected to avoid interrupting the transfer of earthquake energy from the ground through the bridge. A bridge with this typical design requires a high-cost construction due to the need for a huge section of the bridge to resist the earthquake force demand. Thus, many bridges in Taiwan are designed with a rubber bearing only put in between the column and girder without an anchor system. Thus, the bridge movement by rubber displacement is permissible, but the sliding displacement must be accommodated to limit the movement. The sliding displacement is the method to exploit the friction force provided by the sliding on the top and bottom interface of the rubber with the girder and column to dissipate the earthquake input energy transmitted to the structure. By involving the role of surface friction, the shear force transmitted to the structure can be reduced and the bridge performance optimized. General Functional Bearing Model (GFBM) analysis is a rubber bearing analysis which unmerges the function of friction and restoring force. In contrast with the conventional method, the rubber bearing designed with GFBM analysis may reduce the bridge stiffness and deck acceleration, and it is more convenient because only sliding displacement needs to be controlled. This research proposed GFBM analysis to simulate the rubber bearing that is reflected in the real conditions of bridges in Taiwan.