Bridges

Bridges in seismically active regions must be designed and constructed with special considera- tion of how the structure will respond/perform during an earthquake and immediately afterwards. A key element in such considerations is the expansion joints that accommodate superstructure movements and rotations. If these are unable to allow the seismic ground movements, they may be completely destroyed, perhaps also severely damaging the connecting bridge structure, and emergency or evacuation traffic will be unable to use the bridge when it is needed most. A design feature for expansion joints of the modular type is presented, consisting of a 'fuse element' which will fail in a controlled manner when non-seismic movements are exceeded - thereby protecting the expansion joint and the main structure, and helping the bridge to continue accommodating traffic after the event.