The influence of damping ratios of the structural components should be considered in the responses of a long-span suspension bridge under earthquake effect in three dimensions by the response spectrum method. The modal analysis is conducted by taking into account the different structural component damping ratios. And then the integral damping ratio of the structure is determined by using the mode damping ratio in terms of the maximum mode contribution coefficient. After that, the earthquake responses of a suspension bridge are evaluated by the response spectrum method. Results indicate that the influence of the structural components damping ratios on the structural earthquake response should not be ignored. The integral damping ratio value, being 0.02 for a suspension bridge, as recommended by the “Guidelines for Seismic Design of Highway Bridges”, might lead to a conservative but secure design on the structure.
Key words
long-span suspension bridge /
damping ratio /
mode contribution coefficient /
response spectrum method
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References
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