The Analysis Of The Influence Of Pier And Abutment Under Wave Force In The Sea

With the development of national economy, in order to satisfy the more frequentexchanges between different places,china started to build more large-span bridge across sea.Waves force is huger in sea and it would threat the safety of the bridge. What’s more, thewave motion is unpredictable random process. Static analysis of structure may lead to mistakein the process of design. Therefore, studying the static and dynamic response of the structureunder wave force is necessary.Based on auxiliary piers besides the navigable hole of the Hong Kong-Zhuhai-MacauBridge, used the m method to consider the effect of piles and soil and used the finite elementsoftware ANSYS to establish calculate model. Choosing once-in-a-twenty years wave andusing the morison equation to get the maximum speed force and inertial force of the structurein different section. Studying the influence for the wave force on the pier caused by waterdepths and wave incident angle. Through the comprehensive comparison betweendeformation, stress, choosed to focuse on analyzing the wave force which direction islongitudinal to bridge. Using a extreme wave height 4.5m, T=7.5s, and a extreme depth 7.2mto calucate the response of the structure. The maximum deformation is 6.111 mm, and themaximum stress of piers is 0.629 MPa while the pile maximum tensile stress is 4.45 MPa justunder wave action.B-M spectrum was adopted to obtain the wave spectrum, using the paramete:1/3H=3.0m, T =7.5s. According to the the transfer function between wave force spectrumand wave spectrum, transfered the wave spectrum into a wave force spectrum. Through thestochastic analysis function of ANSYS, choosed the Rayleigh damping, exerted nodeincentive to get the displacement response spectrum, velocity response spectrum and theacceleration response spectrum. The area between the spectral response curve and thehorizontal axis is the response variance. After extracting the 1s result, the standard deviationof each response was known, and it was the maximum value within the scope of theprobability of 68.26%, which could be used to provide guidance for structure design. Throughthe comparative analysis of rusult change caused by different stiffness, different quality, it wasknown that with the improvement of structure stiffness, the structural natural frequency and1 s solution increased.With the increase of quality of structure, the structure naturalfrequency and 1 s solution reduced. When structure natural frequency was close to thefrequency of wave energy, it is easy to cause the resonance of structures, so using the methodof increasing structure stiffness, reducing the quality of the structure to optimize design, caneffectively reduced the influence of wave force.Using harmonic superposition method to get 20 groups of the wave force of each section,then using ANSYS transient analysis to get the structure dynamic response under dynamicaction. Mapping displacement time history curve, moment time history curve, shear timehistory curve in key position of the structure. We can know the most unfavorabledisplacement, bending moment and shear force corresponding appear at the same time. Themost unfavorable stress can be read at this time.Compareing the results of the static calculation, stochastic analysis and time-historyanalysis, known that displacement, internal force and stress increased due to the effect ofdynamic action. In the process of actual design, the designer should use three methods at thesame time,and choose the most adverse internal force for design.