Research On Supporting Length And Vertical Shock Absorption Measures Of Girder Bridge

Under strong ground motion excitations, the relative displacement between superstructure and substructure of the simple supported bridges is too large, this behavior probably causes collapse. If the capping beam of a bridge pier is not wide enough, girder falling is likely to happen, too. And it will bring serious damage after the earthquake. Setting reasonable supporting length is the fundamental measure to avoid collapsing. An accurate finite element model has been created, and the nonlinear time-history analysis also has been completed. After the calculation was completed, the relative displacement between superstructure and substructure of the bridge has been focused. Then, the calculation method of supporting length is suggested.In the near field ground motion, the PGA of vertical components can reach or exceed 1g, vertical seismic components play an important role in structural damage. So, the seismic performance assessment of the bridge is code. Analysis results show that when the vertical seismic component's PGA exceeds 0.5g, bearings will damage. Compare with single IDA record analysis, multirecord IDA analysis can reflect discrete uncertainty of seismic records, and the result is more realistic.In order to avoid the damage of the structure induced by vertical seismic components, a shock attenuation measure is put forward. The measure is that installing dampers besides the bearings which are easy to fail. The analyzing results show that under proper configuration the mitigation devices work effectively in reducing the force of the bridge.