Liujiaxia Bridge Construction Stage Of The Calculation And The Cable's Linear Control

Liujiaxia bridge is the largest span suspension bridge in Northwest China, which main span is 536 m. It is currently the same type of large span highway bridge in the most narrow suspension bridge, the bridge width is only 1/34.4, wide span ratio is only 15.6m. Bridge tower for the first time with a large diameter steel tube concrete diameter reach 3000 mm,which is currently the world diameter maximum concrete filled steel tubular structure. The tower design novel and beautiful appearance that the Islamic architectural style,which embodies the unique cultural characteristics of ethnic minority region. The bridge is 536 m single cross truss stiffening girder suspension bridge, in the design into a state of the bridge, crossing theory sag is 48.7m, sag span ratio 1:11, main cable center distance for 15.6m, sling standard spacing 8.0m. In the construction process, it is the key to achieve the design requirements of the main cable's linear control, in particular the installation of reference cable unit, positioning lock monitoring and control is the bridge alignment can meet the design requirements.This paper of Liujiaxia bridge of the whole construction process were tracking detection research, in the process of construction and detection, using the BNLAS software for modeling, which the whole construction process divided 23 construction stages.With constant changes in the construction stage, it is concluded that the different stages that the control point displacement and the theory data of force, as the reference standard in the construction site in the process of detection. On the site construction process control point of displacement monitoring and control section of the stress monitoring. The field data and theoretical design of the data were compared and analyzed, so as to make the corresponding adjustment, the design requirements of the various construction stages of the conclusion, which make the implementation process effectively monitoring.Ideal into the state of the bridge structure under constant load state of the main tower tower has no bias; for the main tower is designed to design an ideal state will not produce bending moment. But the cross effect on main cable load are not equal, especially the construction of the main truss hoisting process and midspan sag with the main truss hoisting changing. Pylon tower have to cross the offset. The main tower of moment, in order to ensure the bridge cable saddle position design, designing according to three times push way cable saddle pushing in place, to eliminate the tower bending moment. The saddle is mounted eccentrically and construction process of bridge deflection and vertical cable real-time monitoring and control, electing to measure the appropriate time for pushing, pushing quantity on-site and real-time adjustment, finally get the ideal shape of main cable, the eccentric moment of tower also control within the range of allowable design.