Mechanical Characteristic Analysis of Negative Moment Zone of Continuous Steel-concrete Box Girder
Steel-concrete box girder has the advantages of fast construction speed,strong crossing ability,saving project cost,etc.In recent years,it is more and more used in bridge construction.Taking Xingci Avenue Expressway across Sizaopu River continuous steel-concrete mixed composite beam bridge as the engineering background,a variety of negative moment treatment methods for steel-concrete composite beam are introduced.Finite element software is used to establish a space grid model,and the influence of the pou-ring sequence and the lifting height on the stress of the bridge panels and steel beams in the negative moment zone of the composite beam bridge is analyzed,which provides a theoretical basis for the cracking control of the negative moment concrete bridge panels of the same type of bridges.The analysis results show that the tensile stress of bridge slab concrete can be significantly reduced by using the method of first span and then fulcrum placement compared with the sequential placement.The combination construction of middle ful-crum jacking and adjusting concrete placement sequence can reserve more pre-compression stress for the operation stage of bridge panels to prevent cracking,and the pre-compression stress increases with the increase of fulcrum jacking height.
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