The Key Technology for Factory-Production of Large-Span Steel-Concrete Box Girder
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摘要: 采用新型材料粗骨料活性粉末混凝土桥面板的新型钢-混凝土组合箱梁,具有高抗压、高抗拉、高弹性模量的优点。在不改变钢混组合结构优良力学性能的前提下,较传统钢混组合箱梁可有效减小桥面板的结构尺寸,达到减轻组合梁自重,提升大跨径跨越能力的优势。虽然该新型钢混组合箱梁有诸多优点,但同时也存在桥面板预制精度高、开口钢梁刚度弱、几何尺寸控制难度高、桥面板与钢梁叠合精度要求高、节段匹配及预拼线形要求高、湿接缝施工中钢筋定位尺寸和结构尺寸的二次变形控制难度大的施工难点。现有施工技术无法满足施工质量和精度控制目标,为此本技术针对该新型钢混组合箱梁的工厂化制造开展技术攻关,形成一整套的技术创新成果,主要包括:1)研发了混凝土桥面板高精度预制技术,该技术通过基线法控制预埋件制作精度、大型高精度组合式模具的应用和智能化生产线的标准化预制工艺,实现对新型钢-粗骨料活性粉末混凝土桥面板钢筋和预埋钢构件的精确定位及整体外形尺寸的精确控制。2)研发了钢混组合梁高精度总拼技术,该技术通过带拱无裕量连续匹配总拼、测控网测控、匹配约束定位工艺、预制桥面板高精度叠合工艺,实现对新型桥面板钢混组合箱梁高精度总拼控制。3)研发了纵向湿接缝施工精度控制技术,该技术通过刚性支撑复原系统、可调式组合湿接缝底模、高精度钢筋定位模具及智能化湿接缝施工生产线,实现湿接缝钢筋高精度定位及组合梁整体尺寸精度控制。目前技术成果已成功应用于南京长江第五大桥跨江主桥的钢混组合梁的工厂化制造,通过检测验收及桥位的安装验证,实现了新型钢混组合箱梁制造精度控制目标,保证了桥梁顺利安装架设。Abstract: 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.
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