Study On Construction Control For Twin-tower Double Cable Plane Pre-stressed Concrete Cable-stayed Bridge(Nanping Minjiang River Bridge)(Case Study)

As the cable-stayed bridge structure is more complex,and the bridge in the formation process will be subject to various unfavorable factors;therefore,the internal force and geometry of the bridge structure will change with external conditions.In order to safeguard the integrity of the cable-stayed bridge during the construction process and to ensure the bridge can meet all the design requirements upon completion,strict construction safety control needs to be implemented during the entire construction process.In this paper,the construction control technology of the NanpingMinjiang Bridge is studied,and its techniques can be used as technical references for the construction monitoring process of futuretwin-tower double-cable plane pre-stressed concrete stayed bridges.The main work and main conclusions are as follows:(1)The construction of the MinjiangBridge is based on the finite element model.The deflection of main girder and main girder phase after cable adjustment are obtained(secondary dead load action,fifty percent vehicle load action and shrinkage creep action)to determine the camber of the bridge.The force of the bridge during the construction phase is analyzed comprehensively.At the same time,the use of the finite element model plays a major role in monitoring the construction and the implementation of construction control over the various nodes.(2)By dividing the construction control monitoring into the main beam elevation observation,the main tower deviation observation,cable force monitoring and stress monitoring of the four major projects,The instrument were used in each monitoring part and the measurement precautions were analyzed and studied so as to be able to carry out the implementation more effectively in the later actual operation process.(3)As the structure of NanpingMinjiang River Bridge is a one-way longitudinal slope,and the asymmetry of the bridge structure is caused by the asymmetry of the main beam in the cantilever construction process of unbalanced horizontal force,and the cable force on both sides of the main span is asymmetric.In order to balance the deflection of the main girder and the horizontal displacement of the bridge tower,the cable force of the stay cable is precisely and rationally determined by the construction monitoring.The structural form of the one-way longitudinal slope under the full floating system has led to the displacement monitoring of the girder as the focus of construction monitoring.(4)Through the data collected during the elevation,stress and cable-stayed force in the main construction stages,the detailed analysis indicates the following conclusion:the main girder alignment,main girder stress tension and cable force,as well as other major design parameters and measured value of the site meet all specification requirements,thus achieve the purpose of the bridge construction control monitoring.