Research On The Superstructure Of Offshore Box Girder Bridge Under Extreme Waves

In recent decades,coastal economic zones have developed rapidly,and some offshore bridges have been built to ensure the economic development of coastal areas.However,typhoons occur frequently in coastal areas of China and cause a lot of property losses every year.When a typhoon comes,the huge waves cause great harm to the bridge.Although there has not been any catastrophe failure of bridges caused by the action of typhoons and waves in our country,the safety of offshore bridged should not be ignored.Therefore,it is of great significance to study the stress of offshore bridge superstructure under extreme wave action.This article focuses on the wave forces on the superstructure of box girder bridges.The main research contents are as follows:(1)Firstly,the research background and significance of this topic are pointed out,the basic wave theory is discussed,the research status of wave flume and the interaction between wave and superstructure is summarized,and the box section bridge is selected for research according to the actual situation of the existing bridges.(2)Based on the basic theory of Computational Fluid Dynamics and the VOF method,a three-dimensional numerical wave flume model was established.The number of elements and iteration time step were optimized by numerical simulation.The accuracy of the model was verified by comparing the results with the experimental and theoretical formulas.(3)Using solitary waves to simulate the tsunami,a three-dimensional model of the superstructure of the box girder bridge under the action of solitary waves was established,the characteristics of the wave force on the superstructure of the box girder bridge were analyzed,the failure types of superstructure under wave action are briefly described to determine the input range of each working condition.(4)Calculate the force of the superstructure under various working conditions through numerical simulation,and it is concluded that the horizontal wave force and vertical wave force firstly increase and then tend to be gentle with the wave height;the increase in water depth has a significant effect on the attenuation of solitary waves.Certain influence,but the general trend is that with the increase of water depth,the horizontal wave force and vertical wave force show a trend of first decreasing and then increasing;when the box girder submergence coefficient is 0.5,the horizontal wave force and vertical wave force Is the maximum value.As the submerged coefficient increases,the horizontal wave force first decreases and then increases,and the vertical wave force first increases and then decreases;changing the height of the box girder has an effect on the horizontal wave force and vertical wave force.The influence of the square wave force is greater than changing the width of the beam bottom.Increasing the width of the beam bottom shows a trend of first increase and then decrease in the horizontal wave force and vertical wave force.Increasing the height of the box girder increases the horizontal wave force and vertical wave force.And the growth rate continues to increase.