耐候钢-混凝土组合结构加劲梁悬索桥的技术创新

Technical Innovation of Weathering Steel-Concrete Composite Stiffened Girder Suspension Bridge

怀来县官厅水库特大桥是北京冬奥会的配套工程,全国首座采用免涂装耐候钢的组合结构加劲梁悬索桥,720 m主跨为我国北方地区最大跨度桥梁。采用钢-混组合结构作为悬索桥的加劲梁,可从根本上解决钢桥面板开裂、桥面铺装病害等问题,同时大幅降低运营维护费用;免涂装耐候钢,具有经济、环保的特点,但国内缺少大规模成功应用的工程范例,也没有免涂装耐候钢桥设计及施工标准。结合大桥建设的条件和要求,对大跨度悬索桥钢-混组合结构加劲梁、高性能耐候钢轧制及焊接、耐候钢桥梁锈层稳定化及制造架设等三大难题开展了技术研究。研究结果表明:钢-混组合梁采用密横梁结构,设置2道次纵梁作为下稳定板,外侧设置风嘴,颤振临界风速达到51.5 m/s,钢-混组合结构加劲梁与抗风措施对千米级悬索桥具有较好的疲劳受力性能和经济适用性;耐候桥梁钢采用“微合金化、热机械轧制”生产工艺,研制的配套焊材与焊接方法具有“耐候性、高韧性”特点,焊缝耐候指数大于6.2,实现了钢结构桥梁低碳建造、绿色环保;采用免涂装耐候钢,与“普通钢材+涂装”相比,全寿命周期成本降低约55%;耐候桥梁钢采用加速锈层稳定化工艺,以及钢-混组合结构加劲梁架设方法,满足了大跨度悬索桥建设与运营的要求。

The Guanting Reservoir Bridge in Huailai County is a supporting project for Beijing Winter Olympics and the first composite stiffened girder suspension bridge in China that uses coating free weathering steel.The main span of the Guanting Reservoir Bridge is 720 m and the largest span bridge in northern China.The use of steel-concrete composite structure as the stiffening beam of suspension bridge can fundamentally solve the problems of steel deck cracking and deck pavement problems,and significantly reduce the operation and maintenance costs.Coating-free weathering steel has the characteristics of economy and environmental protection,but there has been no successful large-scale engineering application in China,nor the design and construction standards for coating-free weathering steel bridges.In combination with the conditions and requirements of the bridge construction,technical researches are carried out on three major problems of steel-concrete composite girder of long-span suspension bridge,rolling and welding of high-performance weathering steel,rust layer stabilization of weathering steel,manufacturing and erection.The research results show that:the steel-concrete composite girder adopts a dense crossbeam structure with two longitudinal beams as the lower stabilizing plate and wind fairing on the outer side,and the critical flutter wind speed reaches 51.5 m/s;The measures for steel-concrete composite stiffened girder and wind resistance have good fatigue performance and economic applicability for kilometer level suspension bridges;The weathering steel for bridge employs the production process of“micro alloying and thermo mechanical rolling”,the developed supporting welding materials and welding methods are of“weather resistance and high toughness”,and the weathering index of the weld seam is greater than 6.2,achieving low-carbon construction and green environmental protection of steel structure bridges;The use of coating-free weathering steel reduces the life cycle cost by about 55%compared with ordinary coating steel;The weathering steel for bridge is manufactured by means of accelerated rust layer stabilization process and the steel-concrete composite stiffened girder erection method,which better meets the requirements of long-span suspension bridge construction and operation with good application and promotion prospects.