The Parameter Research Of Seismic Retrofit On Skew Girder Bridge

Due to the advantages of route trend and cost saving, skew bridges widely exist in the construction of infrastructure. The new 《China seismic ground motion parameter zonation)) will be implemented in June 1,2016. Many of the skew bridge already can’t satisfy the seismic requirements at the present stage, so it need to be strengthened. In view of the less research on vibration reduction and seismic reinforcement of medium and small span skew girder bridge, therefore, this paper which chooses a slope for 30 degrees of three span continuous skew box girder bridge as the research object, focus on the analysis of dynamic response of support under earthquake and the vibration reduction effect of viscous dampers under different layout scheme and damper parameters. At the same time, the seismic response of the bridge with the combined vibration reduction measures of viscous damper and cable, the damping effect of bridge parameters such as foundation type, width span ratio, are all discussed. The main results are as follows:Result OneThe cross horizontal earthquake shear is mainly composed of the abutment bearing. Compared with the bearing on pier, the bearing model of the abutment is small, so yield bearing usually happen at the abutment yield easily. The abutment bearing yield effect of the skew girder bridge under the analysis of strong earthquake response need to be considered.Result TwoThe damping effect of the damper added in the abutment significantly is better than the damping effect of the damper added in bridge pier. When we adopt the reasonable scheme of damper that set at the abutment, the damper has good shock absorption rate not only to the bending moment and displacement, and also have very good improvement effect to the collision, torque, girder plane rotation etc. For bearing yield, the damper has a minimal effect, namely the bearing yield after adding damper on the abutment still occur. The seismic wave with different frequency spectrum has a great influence on the damping effect of the viscous damper. In this paper, the damping effect of the synthetic wave is better than the damping effect of the Taft wave.Result ThreeConsidering the damping effect with the cable and damper, although the cable can produce force, the influence on the internal forces of the fixed piers is very small, and the cable can not meet the expected effect that contrasted with the scheme of damper that set at the abutment.Result FourThe bridge pier under the rare earthquake that enters the plastic state will significantly reduce the internal force. The damper that set in abutment can significantly reduce the curvature of the fixed pier bottom section and reduce earthquake damage.Result FiveNo matter whether or not to consider the "collision constraint", in the consolidation conditions of the pier bottom,the internal force of the structure will increase, and the displacement will response. The damping effect of viscous damper in consideration of pile and soil interaction is better than in the consolidation condition of the pier bottom. Under the same ground motion, the longitudinal maximum displacement of the beam end in the two working conditions is very close, and the viscous damper has a good universality.Result SixThe maximum collision force of wide box girder bridge and narrow box girder bridge occurred in the narrow angle, and the collision force of wide box girder bridge is greater than that of the narrow box girder bridge. The displacement response of the longitudinal bridge under the same span is much larger than that of the narrow box girder bridge. The damping effect of wide box girder bridge with viscous dampers is slightly better than that of the narrow box girder bridge.