Response and Control of Seismic Relative Displacement Between the Long-Span Rail-Cum-Road Cable-Stayed Bridge and the Approach Bridge

Abstract:

Based on the fourth Panama Canal Bridge， the seismic relative displacement responses and control of the main-approach bridge of the rail-cum-road cable-stayed bridge were studied. Finite element analysis models of floating aseismic design， tower-girder consolidation aseismic design and consolidation aseismic design were developed， and the relative displacement responses of the three design schemes were computed. The effects of the differences in nature periods and damping characteristics of two adjacent single-degree-of-freedom systems on their relative displacements were analyzed. In combination with theoretical and parameter analyses， the control method on the relative displacement of the main-approach bridge was investigated. The results show that period ratios of the first longitudinal modes， the equivalent damping ratios and the damping mechanism of the main bridge and the approach bridge have significant influences on the relative displacement of adjacent structures， and the period ratio is the most influential factor. Different arrangements of the viscous dampers have different controlling effects on the relative displacement of the main-approach bridge. Fixing all viscous dampers between the girder ends of the main-approach bridges could enhance the synchronicity of the motion of the two adjacent structures and consequently obtain the best controlling effects. Simultaneously using some dampers on the main bridge piers and the others at the connection of the girders could benefit the configuration design and installation of the system， although the reduction of the relative displacement is a little lower.