Fundamental study on the effects of shape and size of rubber shock absorber on mitigation of impact forces

It has been considered in the Japanese highway bridge design specifications that a large gap between bridge girders may be better than a small one, since the pounding phenomenon may be avoided. However, if a large gap is adopted, the expansion joints will be larger and the construction cost will increase. In order to decrease the construction cost, gap reduction is expected with due care to the pounding of bridge girders, resulting in the prevention of girder falling. Even if a small gap is employed, the damage of the ends of bridge girders and the pier bottoms due to the pounding will be reduced by attaching rubber shock absorbers to the ends of bridge girders. It follows from this that the effective shape and size of rubber shock absorbers should be clarified beforehand. Current analytical studies on rubber shock absorbers are mostly devoted to seismic response analyses with two-dimensional frame models. In this study, the impact analysis with three-dimensional finite element models of steel plates and rubber shock absorbers will be carried out by changing impact velocity, thicknesses and widths of rubber shock absorbers. The effects of shape and size of rubber shock absorber on the mitigation of impact forces will be fully examined.