Hoisting and Matching Techniques for Large Steel Box Girder Segments of Main Bridge of Zhongshan Bridge of Shenzhen-Zhongshan Link
The main bridge of Zhongshan Bridge forming a part of the Shenzhen-Zhongshan Link is a cable-stayed bridge with a main span of 580 m.The stay cables are fanned out in double cable planes.Measured 46 m in width(with wind fairings),the superstructure consists of streamlined flat steel box girders.To facilitate construction,the steel box girders were fabricated into 69 segments that could be erected by balanced cantilever method using deck cranes,with typical segment length of 18 m and maximum hoisting weight of 429 t.The steel box girder segments are heavy and wide,but owes relatively small vertical stiffness across bridge width,as a result,the elevation difference of two adjacent segments is big once they are placed into position,and the maximum elevation difference reaches about 63 mm.To achieve precise matching of steel box girder segments,three solutions were proposed,including the solution of using portal frames and stays,the solution of using bracket reaction frame,and the solution of using cross beams for locking,C-shaped welds and tensioning partial stay cables.In accordance with the finite element analysis,the last solution was finally selected.Taking the vertical web of the box girder as the anchor point,the cross beam was welded in advance,and then connected with a flange,afterwards the girder segment waiting for placement was locked.Subsequently,the girder segment was partially welded with the already-placed girder segment,forming C-shaped welds.To reduce the vertical deformation across bridge width of the already-placed girder segment and reach the matching precision of the segments,the stay cables suspending the next waiting-segment were installed and tensioned to a degree.During the construction,the elevation difference of adjacent girder segments was tuned,local stresses were monitored and the seams between adjacent girder segments were controlled,as a result,the elevation differences of the matching surfaces of the adjacent girder segments were controlled less than 9.8 mm,the local stresses in the steel box girder were under good control,during the initial tensioning of the stay cables,the stress increment of the steel box girder was less than 10 MPa,and the seams between adjacent girder segments were less than 1 cm.
cable-stayed bridgestreamlined flat steel box girderbalanced cantilever erectionhoisting and matchingelevation difference of matching surfacesscheme selectionfinite element methodconstruction technique
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