Study On Construction Process Optimization Of Stiffening Beam Of Long-span Steel Truss Suspension Bridge

For long-span steel truss suspension bridge,there will be problems such as weak stiffness,large deformation and difficult closure during the hoisting and closure of stiffening beams.It is very important for the quality and construction period control of the whole construction process of the stiffening beam to correctly set the temporary hinges in the lifting of the stiffening beam segment,determine the reasonable number and position of hinges,and select the appropriate rigid connection method to complete the conversion of the stiffening beam system.Based on the construction of stiffening beam of hexiandu Wujiang River Bridge,this paper establishes a finite element analysis model,compares and analyzes the response of different hinge setting schemes to the structure during the hoisting of stiffening beam segments,and determines the reasonable number of temporary connections.Then it discusses the hinge fixation conversion after the hoisting of stiffening beam segments,analyzes the traditional rigid connection method and improved optimization method,and discusses the hinge setting and hinge fixation conversion,The main contents are as follows:(1)Compared and analyzed the influence of all hinged,two-stage hinged,three-stage hinged,four-stage hinged,six-stage hinged,five hinged schemes on the stress,line shape,main cable line shape,sling cable force and lower edge opening of the stiffening beam,and concluded that all hinged and two-stage hinged schemes can better meet the needs of Engineering installation,but all hinged schemes will weaken the stiffness of the stiffening beam during construction,increase the cost of temporary measures and relatively long construction period.The actual bridge is implemented according to the method of two-stage hinge setting,and the field monitoring is carried out.The measured results are in good agreement with the theoretical analysis results,which verifies that the two-stage hinge setting scheme is appropriate.(2)After the hoisting of the stiffening beam is completed,the next step of hinge fixation conversion construction is carried out.The effects of the second stage load and other replacement weights and the direct rigid connection without counterweight on the changes of the stress,line shape,sling force and lower edge opening of the stiffening beam are analyzed and compared.The influence of two new construction schemes(scheme 1 and scheme 2)on the structural stress system or bridge state is simulated.The simulation results show that the overall effect is good when the construction is carried out according to scheme 1.(3)The temperature factor is included in the analysis of the hinge fixation conversion process.Four schemes of overall cooling of 5℃ and 10℃ and overall heating of 10℃ and 15℃ are considered.The relationship between the stress,line shape,cable force,lower edge opening and temperature in different stiffening beam rigid connection optimization schemes is discussed.It is proposed that the appropriate ambient temperature in the hinge fixation conversion process is 10℃～15℃,but the corresponding temperature correction should be carried out according to the actual situation in the actual construction,Ensure the smooth progress of hinge and fixation conversion.