| With the wide application of steel-concrete composite structure,the problem of cracking in negative moment zone of steel-concrete composite continuous beam has been paid more and more attention.At present,prestressing in negative moment zone is a common engineering method to prevent concrete cracking.However,due to the characteristics of composite sections,a considerable part of the prestressing force will be consumed by the steel box girder,and the efficiency of the prestressing force is low.Therefore,in order to improve the anti-cracking performance of the negative bending moment zone of the continuous steel-concrete composite beam,this paper relies on the construction background of the second bridge of the Xiaoqing River extra-large bridge in Gaoguang section of the chang-shen Expressway,and based on the compression folding effect of the corrugated steel plate,a new type of steel-concrete composite continuous beam with corrugated steel webs instead of plain steel webs is proposed and its crack resistance is studied.The main work and research results of this paper are as follows:(1)the efficiency of prestressing force is defined by the increment of internal force under axial compression,the wrinkling effect of corrugated steel webs increases the prestressing efficiency by 20%,and the compressive stress increment before and after tension increases by 40% compared with that of plain steel webs,the crack resistance of the structure in the negative moment zone is improved obviously.(2)the scale model test and finite element analysis of a three-span steel-concrete composite continuous beam are completed,in this paper,the cracks,deflections,strains of steel box girder,concrete top plate and steel bar in plate are compared between steel-concrete composite continuous box girder with flat steel web and steel-concrete composite continuous box girder with corrugated steel web under negative bending moment,the effectiveness of using corrugated steel webs in negative moment zone to enhance the crack resistance of reinforced concrete roof is verified.(3)the factors affecting the efficiency of prestressing are analyzed,and the sensitivity of the parameters such as the height of corrugated steel webs,the thickness of corrugated steel webs and the bending angle of corrugated steel webs are analyzed.The key design factors of the new structure are obtained.In this paper,a new technique is proposed to improve the crack resistance of steel-concrete composite continuous beams in negative moment zone,which has important theoretical significance and practical value. |
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