Jishuang Expressway Overpass Bridge, Jilin

This project is an expressway bridge. The single span length of the bridge does not exceed 150 m. The seismic fortification category is Class B. Seismic design calculation is not required for the bridge; only seismic mitigation measures shall be implemented.

Seismic fortification objectives: Under E1 seismic action, the bridge shall generally remain undamaged or remain serviceable without repair. Under E2 seismic action, collapse or severe structural damage shall be avoided, and the bridge can maintain emergency traffic after temporary reinforcement.

Seismic mitigation measures adopted in this design are as follows:

1.When dividing the structure into segments, the height and dimension of piers shall be kept as consistent as possible to ensure uniform distribution of seismic force among piers.

2.Longitudinal and transverse restraining devices (such as stoppers) shall be installed to limit the displacement of the superstructure and prevent beam fall-off.

3.The distance from the end of simply-supported beams to the edge of pier caps or bent caps shall be reasonably defined, and necessary measures shall be taken to prevent beam fall-off.

4.Rubber bearing pads shall be installed between adjacent beams and between beams and abutment backwalls.

5.Plate rubber bearings are primarily adopted for conventional bridges to lengthen the natural vibration period and reduce seismic force.