Time History Analysis of Wind-wave Combined Action on the Maximum Double Cantilever Structure of Rigid Frame Bridge Based on Wave Spectrum Fitting of Random Waves

Offshore structures are primarily subjected to wind and wave interactions, which are inherently coupled and mutually influence each other. It is necessary to study the mechanism of extreme wind-wave combined action on offshore structures especially unstable ones for their safety and performance. Utilizing the theory of random waves, this study examines irregular wave actions, focusing specifically on the maximal double-cantilever configuration of a continuous rigid frame bridge during construction. The dynamic response of the structure under extreme wind-wave combinations is analyzed, accounting for the effects of flow velocity and piles-group interactions. By comparing with the results of regular wave analysis, it was found that under the corresponding combination of load conditions, the maximum displacement effect of the structure obtained by using irregular waves was about 20% greater than that obtained by using regular waves, and the maximum internal force effect was about 10% greater. Therefore, using regular waves for structural dynamic analysis may result in smaller results and underestimate the structural responses.