Research On Wind Resistance Of Construction Process Of Steel Arches In Mountainous Area

With the construction of a large number of bridges in mountainous area,the study of wind-resistant performance of bridges in mountainous area is becoming more and more important.The bridges in mountainous area are usually across canyons,and the wind characteristics of bridge sites are extremely complex,so the relevant regulations in the current wind-resistant codes are no longer applicable.There are few research data on wind-resistance of bridges in mountainous area at home and abroad,and these data are not universal.This paper takes the project of Changing cableway into bridge in Fengjiaping Village of Butuo County as an example,which is located in typical mountain canyon landforms.Then it would ansyze the wind-resistant performance of the steel arches during the construction process.The main contents of this paper are as follows:(1)By consulting and summarizing the existing literatures on wind characteristics in mountainous areas,the basic wind speed analysis method for virtual standard meteorological stations on the bridge site is adopted.On this basis,it is necessary to collect the wind speed data of meteorological stations near the bridge site and revise altitude of wind speed firstly,then,the basic wind speed on bridge site is calculated by using the weighted interpolation method of inverse distance,which takes mountain shelter and distance factor into account.After modifying the basic wind speed according to terrain and referring to wind parameters of other bridges,which are from the topographic model test or CFD,it could make sure the wind speed of bridge position.(2)The finite element model of steel arches is established by ANSYS.The equivalent bending moment of inertia is obtained by decomposing the steel truss into equivalent plane truss,and the equivalent torsional inertia moment of steel truss is obtained by transforming the steel truss into thin-walled beam structure equivalently,which has a single box and two chambers.Then the equivalent single beam model is established.The validity of the steel arches model is verified by comparing the actual model and the equivalent model of steel arches.On this basis,the dynamic characteristics of the steel arches model in each construction stage are analyzed.(3)The basic knowledge of computational fluid dynamics is reviewed,and the calculation of the three component coeffcients of steel arches is carried out by using CFD software.In order to ensure the accuracy of the calculation results,it is useful to obtain the optimal mesh division by adjusting the number of meshes under the same Reynolds number,and it is also necessary to adjust Reynolds number to obtain the best Reynolds number under the same meshes.On this basis,three component coeffcients of steel arches section at-10°~10°angle of attack are calculated.(4)The analysis of static wind response and d wind vibration response for steel arches models in each stage of construction are carried out by using two analysis methods,which only consider the resistance coefficient from the wind resistance code and the three component coeffcients taking into account the variation of wind attack angle.The results show that the stress of each member of steel arches meets the design strength requirement,and the displacement response is small.By comparing the differences of response between the two analysis methods,it is concluded that the results of static wind response under the resistance are larger than the results of static wind response considering the three component coeffcients.The results of dynamic wind response of the two analytical methods are basically consistent.