复杂环境钢-混组合梁斜拉桥主梁拼装施工研究OA

The Yongjiang Extra Large Bridge is a three-tower asymmetric cable-stayed bridge with steel-concrete composite girders,and its span arrangement is(50+275+540+570+214+81)m.Restricted by special environments such as the hazardous chemical port area,the integral segment hoisting method commonly adopted for the construc-tion of steel-concrete composite girders cannot be implemented.Therefore,an 80 t slewing crane was used for piece-by-piece assembly of the main girder components.Meanwhile,to achieve the full-bridge closure before the arrival of typhoon season,a construction technology featuring delayed forward movement of the crane and pre-de-flection installation of side main girders was proposed on the basis of the conventional"two segments per cycle"construction method.To verify the feasibility of the construction scheme,ANSYS software was adopted to establish a three-dimensional finite element model of main girder segments,and the structural stress and deformation during hoisting construction were simulated and analyzed.The calculation results show that the stresses of the steel struc-ture of the main girder and concrete bridge deck remain within the safe range throughout the assembly process.The side main girders undergo torsional deformation under the action of self-weight and hoisting loads,and such defor-mation transmits to the cantilever front end and accumulates.Appropriately keeping the crane away from the can-tilever end and presetting a reverse deflection of 1.5 mm for the side main girders can effectively reduce the accumu-lation of torsional deformation and ensure smooth splicing of cross beams.Engineering practice demonstrates that the"two segments per cycle"construction scheme improves the construction efficiency of the main girder and provides valuable reference for the construction of similar bridges under complex environments.