Study on Pounding Effect Between Long Span Suspension Bridge and Approach Bridge Under Earthquake

Abstract

Expansion joints are important connecting members between long-span suspension bridge and approach bridge. Since the longitudinal vibration is coupled between the suspension bridge and approach bridge under a strong earthquake, accidences of pounding and falling may happen between the girders on both sides of the expansion joints. In this study the influence of pounding effect on seismic response of bridge is analyzed by nonlinear time history seismic method based on a real long-span suspension bridge. The influences of pounding stiffness and initial width of expansion joint are both considered in this paper. The results show that pounding stiffness has a great impact on the bending moment at the bottom section of piers and the longitudinal displacement of approach bridge. Meanwhile the analysis tells that different anti-push stiffening between two approach bridges will lead to a variety of pounding effect. Under the designed earthquake intensity, long-period seismic earthquake creates a very large pounding force between stiffening girder of suspension bridge and box girder of approach bridge, which may cause local damage of the girders.