Research On Wave Spectrum And Random Wave Force On Coastal Bridge

With the development of the economy and the increasing trade,the sea-crossing bridges across the two sides of the strait have great significance for economic development and trade.Unlike bridges built on land,sea-crossing bridges are often located in the nearshore region.The wave force on bridges is also an important control load that cannot be ignored.Under extreme conditions such as hurricanes and tsunamis,wave forces will be the main cause of damage to sea-crossing bridges.Therefore,it is urgent to analyze and study the random wave and random wave force in the bridge site area through the measured data,which has important theoretical and practical value for the construction,operation and maintenance of the bridge.Based on the elevation data measured by acoustic wave instrument in the site area of the Pingtan Straits Rail-cum-Road Combined Bridge,this paper has researched on the wave spectrum.The main ideas and work have been listed below:(1)Using the acoustic wave instrument as the collection instrument,we have measured the wave surface data of the Pingtan Strait bridge site for two years.In view of the commonness of noise influence in the measured data,it is difficult to directly use or the denoising method is cumbersome and difficult to apply.For the problem,this article strives to ensure the simplicity and speed of the algorithm and the accuracy of data denoising.A method for identifying and reconstructing ocean wave error data based on compressed sensing algorithms is proposed.When the data error rate is less than 40%,the method can perfectly reconstruction of the data ensures the authenticity and accuracy of the data.At the same time,based on the MATLAB software platform,the method proposed in this paper is written in BIAS software,and the method and steps of use are introduced in detail.(2)The method for establishing random wave spectra in this paper is reasonable and accurate.Firstly,the measured wave spectra are divided into six groups according to the effective wave height.In order to ensure the reliability and accuracy of the fitting results,7084six-parameter spectra are obtained by nonlinear least squares fitting,and the peak of the spectrum is strictly controlled.The error is within 10%.The spectrum parameters are statistically analyzed by probability density statistical analysis method,and finally a random wave spectrum family in the bridge site area of Pingtan Bridge is established.Based on the double-peak characteristics of the measured wave spectrum of the Pingtan Bridge site area,the random wave spectrum proposed in this paper is composed of high frequency and low frequency.Compared with the existing wave spectrum models(Bretschneider spectrum,P-M spectrum,JONSWAP spectrum),the proposed random wave spectrum is more pertinent in describing waves in the Pingtan sea area,covering a series of measured spectrum shapes in the bridge site area,and can better reflect the diversity and randomness of real waves,In addition the spectrum parameters can be directly determined by the effective wave height.Engineering applications are more convenient and simple.(3)By comparing the calculation results of the wave force on the structure,the random wave spectrum proposed in this paper can effectively and correctly calculate the random wave force on the structure.Considering the large number of wave spectrum families,if only individual wave spectrums are needed,it is recommended the most probable wave spectrum is preferred.For sea areas lacking measured wave data,existing wave spectrum models(P-M spectrum,Bretschneider spectrum,six-parameter spectrum,etc.)can be used;and for sea areas with measured wave data,it is recommended to use the wave spectrum establishment method in this article establish the wave spectrum family in the bridge site based on the measured wave data,because the established random wave spectrum family covers various measured spectrum shapes in a series of historical data over the years,which is more suitable for actual sea conditions than the existing wave spectrum model.It can more reliably and accurately reflect the wave conditions in the bridge site location.