Study on Incremental Launching Scheme of Small-radius High and Wide Gradient Steel Box Girder across Freeway
The incremental launching method is commonly used for the construction across the existing freeways.For small-radius high and wide gradient steel box girders,the traditional method is to use the curved incremental launching scheme.The traditional method has the problems such as complex process,large technical difficulty,long construction period,and high cost of the substructure.And its application scope is limited.Taking the steel box girder of the ramp bridge spanning Guangqing Expressway in Baiyun Line V as the engineering background,the structural characteristics of the small-radius high and wide gradient steel box girder are analyzed in detail,and a new scheme of direct incremental launching of widening curved girder is proposed.The width of the pier top bearing beam is reasonably arranged according to the widening characteristics of the incremental launched girder in order to meet the design requirements of clear stress and reduced steel consumption.The stress of the steel box girder under various working conditions during the incremental launching process is analyzed to verify the rationality of the incremental launching scheme.The direct incremental launching of curved girder has good environmental adaptability,short construction period,clear stress and good economy,which can provide reference for similar incremental launching schemes.
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