Research On The Dynamic Responses Of A Freestanding Bridge Tower Under The Coupling Action Of Wind And Wave

As a current trend in bridge engineering from inland to the coastal areas, some large-span bridges, such as Donghai bridge, Hangzhou Bay bridge Jiaozhou Bay Bridge and so on, have been constructed in the past ten years. In the marine environment, coastal structures sustain more serious environment loads, such as wind, waves and currents, in the construction and service periods. Since the catastrophic disaster of Tacoma bridge, the wind engineering of bridge has been comprehensively investigated. However, few researches were focused on the dynamic behavior of bridge with more complex environments of wind and wave. With the current trend to exploit the deeper water, it is necessary to understand the dynamic response regulation of the large-span bridges in the marine environments.This thesis conducted an experiment and numerical simulation to analyze the dynamic response of bridge tower with the coupling action of wind and wave. The main contents of this study are summarized as follows:(1) The basic process of wind-wave experimental test was introduced, including the similarity criterion and scale ratio for the prototype structure, the designation, manufacture, and assembling of the test model for the experiment, the selection and arrangement for the transducers, the collection and analysis for the test data.(2) Calibration of the wind and wave fields in the laboratory before the test. This study also showed a method to generate the wind-wave field. Furthermore, the influence of the wind and wind-generated wave on the wave trains is discussed to provide the basis for the wind-wave coupling test of the structure model.(3) Based on the comparison and analysis of the test results, the regulation of the structural dynamic responses, including the tip displacement and acceleration, the base shear force and bending moment, were discussed under the wind-only, waveonly and wind-wave cases.(4) Establishment the mechanical analysis model of the bridge tower under the coupling action of wind and wave. Through the numerical simulation, the simulation results were compared with the test results. In the mechanical model, the wind force were simulated by the buffeting theory. The wave force was used the test result and its distribution were simulated by CFD method. The nonlinea r of the structure and transient response caused by the wave load were also thought in the time domain analysis. Moreover, the test results were confirmed and replenished by the numerical results.