| Many bridges were damaged by earthquake in Kumamoto prefecture located southern Japan at 2016. There were damaged even bridges built according to relatively recent seismic standard, and it is important understand the damage mechanism during an earthquake in order to improve seismic technology.In this paper, we investigated the actual damage of “Tawarayama bridge” which had been seriously damaged. In this bridge, the horizontal displacement was surveyed so that the girder crashed with the abutment, and a large residual displacement was also surveyed in the downward direction. As a damage state of the Tawarayama bridge, it was investigated that the rubber bearing was destroyed, and the superstructure fell on the top of substructure. And, it was investigated scratch due to bolts fractured in upper and lower surface of bearing. In addition, since the displacement of the substructure due to ground displacement was also surveyed, it is supposed that a force on the rubber bearing exceeded the design load when the force transmits from the substructure to the superstructure. Generally, it can be said that were the weakest part of the path through which the force transmitted will be broken. In this bridge, thought the bearings were installed on the same pier, the broken parts were different. It suggests that there were several variations of strength or force unexpected in the design has occurred. To improve the reliability of seismic design, it is important to understand the failure mechanism.Therefore, we examined the damage mechanism of Tawarayama bridge from investigation result of deformations that occurred in the superstructure, bottom structure and rubber bearing. |
