Research On Key Construction Technology Of Self-Anchored Suspension Bridge With"Erecting Cable Before Constructing Girder"Scheme

Suspension bridge is widely used in bridge construction because of its beautiful line,clear force and strong crossing ability.The self anchored suspension bridge is an excellent bridge structure because it is anchored to the main beam,which solves the problem that the anchorage structure of ground anchored suspension bridge is limited by geological conditions.The general self anchored suspension bridge adopts the construction method of "erecting cable before constructing girder",which needs to set up temporary piers in the main span,which limits the navigation.In order to solve the limitation of navigation under the bridge in the construction process of self-anchored suspension bridge,there are several solutions in the engineering field,one of which is to set temporary anchoring structure such as anchor ingot.In the process of main girder hoisting,the bridge structure system is self-anchored structure,and then the bridge is converted to self-anchored structure after the bridge is closed.The background project of this paper is Harbour Bridge Across South Tributary of Dongjian River.The bridge adopts the construction scheme of "ground anchor to self anchor" with temporary anchor and temporary stay cable,and adopts the construction method of "erecting cable before constructing girder".Based on this project,this paper has done the following main work:(1)According to different main cable stress analysis methods,three kinds of suspension cable form finding analysis methods are calculated,which are parabola method,pitch line method and catenary method.Based on the catenary method,Parabola to Catenary Iteration method(PTCI method for short)(2)Midas/Civil software is used for the finite element modeling of the harbor bridge.Based on the design parameters,the bridge structure is adjusted to obtain the reasonable completion state of the bridge.According to the overall analysis results of the bridge,the deformation and internal force data of the structure in each construction stage and post-processing stage after closure are obtained.The structure stress and position change during the transition from anchor to anchor are analyzed.According to the lifting point force of the main cable at the completion of the bridge,the calculation results of finite element program and PTCI method are compared.The manufacturing parameters of the main structures of the bridge are determined,according to the overall analysis results of the bridge.(3)Based on the reasonable bridge construction scheme,the overall analysis is carried out step by step.Determine the connection mode of main girder and the closing time of side span and anchor span.Finally,three construction schemes are proposed to meet the requirements of construction control.(4)Optimized on the basis of the overall bridge construction plan,improved the contact problem between cable conduit and sling,refined the classification steps of synchronous lifting,and analyzed the force characteristics of the lifting system in the synchronous lifting process.