Construction Control of Steel Box Girders in Zones Without Hanger Cables in Long-Span Suspension Bridge
The Xiushan Bridge is a suspension bridge featuring the stiffening girder composed of steel boxes.The bridge is of a three-span continuous elastic supporting system,with the main span length reaching 926 m.The steel box girders in the zones without hanger cables were erected on high scaffolds,assisted by permanent hanger cables.The high scaffolds were composed of steel tubes,on the top of which tracks were laid for the longitudinal moving of the girders.The main bridge was numerically simulated in MIDAS Civil software to carry out construction control calculation,and a full-process iteration method based on stress-free curvature was used,to determine the precamber of the scaffolds as well as the assembly alignment of the girders in the zones without hanger cables.As per the calculations,the maximum and minimum precambers of scaffolds in the vicinity of Guanshan-side tower without hanger cables were 0.625 m and 0.600 m,respectively.The maximum bias of the theoretical and design alignments of the girders in the zones without hanger cables was—4 mm.Reaction forces at supports of the scaffolds were even.After closure of the stiffening girder,the tensions of the first pair of hanger cables were only increased by 4.5％,and the internal forces of the steel box girders in the zones without hanger cables showed minimal change.During construction,the steel box girders in the zones without hanger cables were first swung to the stipulated locations by the main-cable-supported cranes,and then precamber of scaffolds as well as the assembly alignment of the steel box girders were adjusted by the hydraulic jacks and tuners.Afterwards,the steel box girders suspended by the first pair of hanger cables were tuned and connected with the neighboring steel box girders in the zones without hanger cables.The scaffolds were dismantled after the completion of the overall loop welding,and in this case,the maximum elevation bias of the girders in the zones without hanger cables was-7 mm,the maximum bias of deck longitudinal gradient was-0.037 3％,meeting the design requirements.After the completion of the bridge,the maximum bias of the longitudinal gradient of steel box girders is 0.264％,indicating smooth alignment.
suspension bridgesteel box girdergirder in zone without hanger cablesscaffoldsfull-process iterationprecamberalignmentconstruction control
NETL
NSTL
万方数据
维普
