The Construction Study Of Beijing Road Bridge Steel Stiffening Girder Suspending Phase

Self-anchored suspension bridges are increasingly appreciated by engineers for their merits such as aesthetic appearance and high adaptability to the land form and geology. It has become a more competitive design scheme in middle-span and small-span in cities. Beijing Road Bridge is a self-anchored steel-concrete composite girder suspension bridges, the stiffened girder of main span adopt steel box girder, and side span adopt prestressed concrete box girder. Considering not affect Jinghang canal go on being open to navigation or air traffic in the course of construction of cable suspension bridge, so the erection of main beam adopt firstly trestle to place concrete main beam, then segmental hanging steel box girder. Based on Beijing Road Bridge construction process, this paper studies the theory and method of self-anchored suspension bridge construction control. The main content as follows:(1) The primary coverage of initial state construction control for self-anchored suspension bridge is illustrated. Moreover, structural geometry and internal force during each stage is analyzed, based on the analytical iteration method and the nonlinear finite element method. Main cable force figure can be simplified as flexible cable with even load and focus force at the hanger, so main cable is more precise seen as segmental catenary than seen as parabola. Main cable configuration of completed bridge is calculated by segmental catenary theory, and the free length of each main cable, the hanger length, free main cable configuration, the saddle pre-offset are also calculated, and the position of each rope clip is determined.(2) In main cable's erection, the influence of unstressed cable-length and main cable span to main cable sag, the relation between main cable cable-length and span , and the relation between main cable sag and temperature are analysed.(3)The phase of steel box girder hanging is a key one in the construction of suspension bridges, in order to ensure compression and shape of suspension bridges after completed, at this stage in the steel box girder hanging process the change rule of main cable, change rule of hanger's pulling force, change rule of stiffened girder's shape and cable saddle's distance need to be pushed out unceasingly as steel box girder be hanged are analysed.(4) The internal force state corresponding to construction method different from stiffened girder is studied, and after stiffened girder being made closure, implement method which steel box girder convert from articulation state to stiff connection state is analysed.