The Key Technology for Factory-Production of Large-Span Steel-Concrete Box Girder

The new steel-coarse aggregate active powder concrete composite box girder deck panel has the advantages of high compressive strength, high tensile strength and high elastic modulus. Under the premise of performance, without changing the excellent mechanics of the steel-concrete composite structure, compared with the traditional steel-concrete composite box girder, the new steel-coarse aggregate active powder concrete composite box girder deck panel can effectively reduce the structural size of the bridge deck, achieve the advantages of reducing the self-weight of the composite girder and improving the long-span spanning capacity. Although the new steel-concrete composite box girder has many advantages, but it still has problems likes the high accuracy of the prefabrication bridge deck panel, low strength of the large opening segment, high degree of difficulty for control the geometric, high accuracy of overlap the bridge deck panel with the steel box girder, high requirements of matching the segments and trial assembly linear control, and it is difficulty to control the secondary deformation of the rebar position and structural geometric of grouting the wet joints. The existing construction technology cannot meet the construction quality and precision control goals. Therefore, this technology is aimed at this new type of steel-concrete composite box girder of the Fifth Nanjing Yangtze River Bridge. The manufacturer CRBBG has research and breakthrough the technology barrier and formed a complete set of technological innovations, mainly including:1) Developed a highprecision precast technology for concrete bridge deck panel, which controls the manufacturing accuracy of embedded parts accordance with control the reference line, the application of large-scale high-precision combined formwork and the standardized prefabrication process of the intelligent production line, achieved the precise control of positioning of the rebars and embedded steel members of the new steel-coarse aggregate active powder concrete bridge deck panel and the overall structure external dimensions. 2) Developed a highprecision trial assembly technology of steel-concrete composite box girder. This technology carried out the continuous trial assembly without allowance of camber design, achieved the precision control referred to the survey and control network, matching constraint positioning technology, and high-precision combined technology of prefabricated bridge deck panel to achieve the precision control purpose of trial assembly for the new type of steel-concrete box girders. 3) Developed the longitudinal wet joint construction precision control technology, which through carried out the rigid support restoration system, adjustable combined wet joint bottom formwork, high-precision rebars positioning formwork and intelligent wet joint construction production system, achieved the high-precision control for positioning of rebars in wet joint and overall structure dimension of steel-concrete box girder. At present, the technical achievements have been successfully used in the factory manufacturing of steel-concrete composite box girder of the main span of the Fifth Nanjing Yangtze River Bridge. Referred to the acceptable factory inspection and verification on construction site, the new steel-concrete composite box girder manufacturing accuracy control goals have been achieved to ensure the successful installation and erection of the bridge.