Study On Average Wind Statistical Analysis And Wind-induced Fatigue Of Suspension Bridge In Mountainous Area Based On Field Measurement

For long-span suspension bridges,the related research of the strength,stiffness and stability of the structure under the action of extreme wind,such as typhoons,is the focus of wind resistance research at present,while the research on structural fatigue caused by the long-term action of environmental wind field is relatively few.The wind-induced buffeting responses of large span flexible suspension bridge in mountainous area under the long-term action of canyon wind field is very significant,and the fatigue damage of bridge components under the long-term action of fluctuating wind load can not be ignored,and even the overall safety of the bridge can be endangered under serious circumstances.Therefore,the life prediction of wind-induced fatigue of long-span suspension bridges in mountainous areas is of great significance to the structural durability design and safety evaluation.Based on the theoretical analysis of wind-induced vibration response and fatigue accumulation damage and the method of field measurement,this paper relies on the measured data of wind field of the structural health monitoring system of a suspension bridge in a mountainous area,and uses engineering software MATLAB and ANSYS for statistical and time domain analysis.The three aspects of the main work are as follows:(1)Based on the statistical method,the distribution law of average wind speed and wind direction at the bridge location is analyzed by using the long-term measured wind speed data of the wind field monitoring system of the suspension bridge in this mountainous area.The results show that the two-parameter Weibull distribution probability model can fit the average wind speed distribution of each wind direction well,and is suitable for statistical analysis of average wind speed.In addition,the average wind speed distribution of each wind direction is mainly concentrated in the low wind speed area,and the relative frequency of high wind speed is small.(2)The spatial finite element model of the bridge is established by using parametric design language APDL,and the buffeting responses time domain analysis of the relevant section of the stiffening beam of the bridge is carried out based on the finite element method,and the stress response time domain of the corresponding rod in the cross section is obtained,which lays a foundation for the analysis of wind-induced buffeting fatigue damage.(3)Using the above analysis results of fatigue wind load and the time domain analysis method of buffeting responses,this paper then analyzes the buffeting fatigue life under the influence of the wind direction of the stiffening beam of the suspension bridge in this mountainous area.The results show that when the wind direction is certain,the buffeting fatigue life of stiffening beam shows a significant decrease with the increase of wind speed.In addition,when the wind speed is certain,the fatigue damage caused on the stiffening beam under the wind load of different wind direction is also quite different,which indicates that the influence of wind direction on the buffeting fatigue life of structure can not be ignored.At the same time,it can be found that when the wind speed is certain,the buffeting fatigue life under the influence of wind direction is longer than when the influence of wind direction is not taken into account,which indicates that when the design of structural wind-induced buffeting fatigue is carried out,the results will be more conservative when the influence of wind direction is not taken into account.Based on the long-term measured wind speed data at the bridge position,the wind-induced buffeting response of the suspension bridge in mountainous area and the fatigue accumulation damage caused by the long-term action of ambient wind load on the structure are analyzed.So as to provide the corresponding basis for the evaluation of the wind resistance safety of the bridge during the operating period.At the same time,it can provide favorable reference for wind resistance design of the same type of long-span bridge in mountainous area.