Numerical investigations of the dynamic response of a floating bridge under environmental loadings

Floating bridges across wide and deep fjords are subjected to the environmental wind and wave loadings. In this study, the dynamic response of floating bridges under such loadings is investigated. A floating bridge concept, which consists of two cable-stayed spans and 19 continuous spans, is selected. An eigenvalue analysis is first conducted and it is found that the period of the first mode is typically in the order of one minute or more. This implies that the amplified response effect should also be evaluated for the second-order wave load in addition to the first-order wave load. By performing a nonlinear time domain dynamic analysis, the bridge dynamic responses from wind and wave loadings are obtained. The effects of the wind load, first-order and second-order wave loads are studied considering different load combinations. Structural responses including girder displacements, accelerations and moments are investigated for each load combination.