Joint Wind-wave Action And Coherence Function Of Large Sea-span Cable-stayed Bridge

In recent years,along with the national comprehensive strength of increasingly powerful,also led to the rapid development of infrastructure construction field,for example,in China’s coastal areas,along with the rapid economic development,convenience and high efficiency of transportation for people put forward higher requirements,including the construction of crosssea Bridges in Marine engineering in order to solve this requirement.Sea-crossing Bridges are usually in the harsh environment of strong wind,high wave and high tide,so the dynamic response of the structure is more obvious under the action of wind,wave and current.In the past studies on the effects of wind and wave on sea-crossing Bridges,only the wind and wave loads were simply superimposed,but in actual situations,there was indeed a certain correlation between wind and wave.When the wind speed is larger,the surface wave is relatively high,so the wind-induced load and superposition of wave force will appear the phenomenon of "combination",the correlation between wind,wave superposition of wave load of structure when the process have a significant impact,so the wind-the joint action of waves and waves simple superposition structure under the action of load effect will also have obvious difference.In this paper,on the basis of the original,according to the correlation between wind and wave factors to consider the size of wind and wave synchronization,and then consider the corresponding wind and wave superimposed load time history is particularly important.In order to obtain the time history of wind-wave factors considering correlation and determine the variation characteristics of the dynamic response of a sea-crossing cable-stayed bridge under its combined action,this paper makes an in-depth study of the correlation wind-wave coherence function and the dynamic response of the sea-crossing cable-stayed bridge under the combined action of the correlation wind-wave.The main results are as follows:(1)To investigate the correlation between wind,wave,using the algorithm of SVM training related to the measured wind-wave data,it is concluded that under different wind wave-correlation training model,build the wind speed spectrum matrix cable-stayed bridge wind field simulation,the simulation of wind field input the wind wave-training model and output the corresponding wave,calculate the numerical solution of wind,wave coherence function.The reasons influencing the coherence of wind-wave were analyzed,the theoretical model of wind-wave coherence function was constructed,the numerical solutions were compared with the theoretical solutions,and the model parameters of the theoretical wind-wave coherence function were optimized and determined.(2)On the basis of the wind-wave coherence function,in order to generate the synchronous wind-wave load with correlation,the wind-wave coherence function model obtained is used to construct the wind-wave joint spectrum matrix.The wind-wave joint spectrum matrix is decomposed by cholesky,and the wind-wave time history with different correlation is generated by the harmonic synthesis method.According to the calculation method of wind load and wave load,the wind-wave coherent function is used to calculate the synchronous windwave load under different correlations.(3)The dynamic response of cable-stayed bridge under the combined action of wind and wave with different correlations is calculated,and the variation rule of the dynamic response is obtained: with the weakening of the correlation between wind and wave,the maximum value of the dynamic response to the excitation of bridge tower under the combined action of wind and wave does not necessarily decrease,but the mean square error basically shows a slightly decreasing trend.For the whole bridge,with the decrease of the wind-wave correlation,the mean square error of base shear and bending moment presents a decreasing trend,but the excitation response value of wave load on the top displacement and mid-span displacement is almost negligible compared with the wind load.