Study On Safety Analysis Of Simply Supported Beam Bridge Under Flood

Flood disaster is still one of the most common natural disasters in the world.It has always been a key factor restricting the development of our country's economic and social development.Floods are seasonal strong disasters,accompanied by the flood of the chain effect exacerbated landslides,debris flow,scouring and floating objects on the formation of the mountains and rivers across the mountains and rivers,and it has brought great harm and caused great losses.In order to ensure the safety of road and bridge,to eliminate the threat of flood disaster,it is very important to analyze the flood risk of river bridge.This paper is based on the specific engineering examples,the use of FLUENT software to study the simulation of bridge under the action of flood safety.In this paper,the safety of the bridge is determined by simulating the influence of the bridge height and the velocity of the bridge on the safety of the bridge,and analyzing the displacement of the pier and the equivalent stress at the end of the pier.Finally,the impact of the bridge under the action of the impact of accidental impact load simulation analysis,the study of the bridge in the most unfavorable conditions of security.The specific research contents and conclusions are as follows:(1)Based on the FLUENT software,the influence of different flood level on the safety of the bridge is analyzed.The results show that with the increase of the water level,the maximum displacement and the maximum equivalent stress Reduced,the height of the water level 25m,the top of the pier displacement exceeds the standard requirements,this time the bridge has the risk of destroyed.(2)Based on the FLUENT software simulation,the influence of different flood water velocity on the safety of the bridge is analyzed.The results show that the bridge can withstand the floods of 5 years,20 years and 50 years.Once the floods,the displacement of the bridge pier top has exceeded the allowable value of the standard,prone to flooding phenomenon.(3)The influence of accidental impact load on the safety of the bridge is simulated and analyzed by LS-DYNA software.The results show that the bridge is subjected to any high impact at the rate of 5 years and 20 years safe.When the impact height is less than 20m,the bridge is safe,and when the impact height is greater than 20m,the bridge is unsafe and easily destroyed by the flood.Bridge in the event of a hundred years of flood speed,as long as the impact height greater than 10m,the bridge is very dangerous,easily washed away by the flood.(4)through the assessment of the risk to determine the risk of flood risk factors.Based on AHP(Analytic Hierarchy Process),the weight ratio of each risk is determined.Finally,the weight ratio of each risk is expressed by the risk degree.The formula is:H = 0.35G1 +0.137G2 + 0.152G3 + 0.158G4 + 0.203G5.