Securing Bridge Girder-End Gap during Earthquake Using Large-deformation Blocks

摘要

The girder-end gap of a bridge should preferably be narrowed from the standpoint of the durability of the expansion joint and noise reduction but is required to be widened, when seismic isolation supports are used, from the aspect of preventing collision. This study began with research into noise generated from expansion joints and the load-bearing capacity of the parapet walls of bridges. Special blocks were then fabricated using a HPFRCC and expanded polystyrene. These are capable of bearing vertical loads including wheel loads on a normal basis, readily having large deformation in the bridge longitudinal direction during an earthquake to follow the sway and slide of the girders, and being easily exchangeable after an earthquake to make the bridge highly restorable. The blocks, which are highly anisotropic in terms of mechanics, were found to provide the expected functions, being deformable in the bridge-axis direction by more than 20%. The inclusion of fibers was effective in preventing scaling from fractured blocks, and the use of expanded polystyrene enabled the blocks to recover more than 50% of their ultimate deformation.