Study On Construction Control And Wind Resistance Of High Pier And Long Span Continuous Rigid Frame Bridge

For the plateau mountainous area with water storage requirements,the valley is generally deep and the slope is steep in this kind of area,and the environment is relatively complex and changeable.The continuous rigid frame bridge with high pier and long span has the advantages of large span,high pier,thin pier wall and relatively simple construction technology,which is widely used in mountainous areas.On the other hand,due to the characteristics of long construction period,light weight,large flexibility,low damping and poor stability of high pier long-span continuous rigid frame bridge,if the construction control is not carried out in time,it may lead to poor structural stress after the completion of the bridge and affect its normal operation;at the same time,due to the complex and changeable wind direction at the bridge site in mountainous areas,it is easy to be affected by the wind load in the bridge construction stage As a result,the bridge is damaged due to instability.Therefore,it is particularly important to study the construction control and wind resistance performance of this kind of bridge.In this paper,the xiatuo super large bridge(110 + 200 + 110)m,a new high pier and longspan continuous rigid frame bridge,is taken as an example to analyze the construction control and wind resistance of the xiatuo super large bridge in the reservoir area of Lianghekou Hydropower Station in Ganzi Tibetan Autonomous Region of Sichuan Province(1)The finite element software MIDAS civil is used to monitor the bridge construction based on the adaptive control theory,and the error is controlled within the specification;The following Tuote bridge engineering example,the sensitivity analysis of the bridge structure,find out the main influence parameters of the linear change of the bridge structure,briefly discuss the application of the least square control method in the bridge linear monitoring,provide reference for similar projects.(2)The stress of the main girder and the key section of the main pier of xiatuo bridge are monitored,adjusted according to the actual construction period,and compared with the theoretical stress.At the same time,the factors affecting the stress monitoring results and stress mutation are analyzed to ensure the accuracy of the stress monitoring results,so that the theoretical and measured stress changes tend to be consistent,and the stress value meets the requirements of the specification.(3)According to the requirements of the 18 th Edition of "code for wind resistant design of highway bridges" and combined with the local environmental characteristics,this paper calculates the design reference wind speed,the design wind speed in the construction stage and the static gust wind speed of xiatuo super large bridge.Through the analysis of the natural vibration characteristics of the bridge,the most unfavorable construction stage is obtained,which lays the foundation for the wind resistance research in the subsequent construction stage.(4)Different from the calculation method of wind load in design code,Midas FEA is used to simulate the flow field around the section of main beam and pier,study the variation of wind load parameters with the section,and calculate the three component value of wind load in different sections;according to the three component value,the static gust load of bridge is determined.(5)The paper analyzes the stress performance of the bridge structure under the action of resistance,lift and torque caused by wind load in the most unfavorable construction stage.According to the 18 edition of code for wind resistance design of highway bridges and the actual situation of bridges,three kinds of most unfavorable load conditions are given,and their internal force,stress and displacement are calculated;The main stress position and maximum displacement direction of the bridge are determined,which provides the basis for the wind load monitoring of the bridge in the future.