Key technology for construction of connection between steel pylon and concrete pile cap of middle pylon of Taizhou Bridge

Taizhou Yangtze River Bridge is a suspension bridge with three pylons and two 1080m main spans. The middle pylon is a steel frame with longitudinal herringbone shape and lateral gate shape. The connection between steel pylon and concrete pile cap is a key part to transfer the huge inner force from the pylon to the foundation. Its construction quality is a critical factor to the overall structural loading of the whole bridge, therefore the contact ratio between the bearing steel plate of pylon and concrete pile cap is required to be over 75%. The inclined joint surface in two directions, longitudinally at 39/1920 and laterally at 1/4, posted a challenge to the construction works. Technological tests were carried out to find an optimal construction method by comparison, and finally the Post-Injection method was selected as it can meet the requirement of concrete strength and contact ratio at the connection. The successfully application of the Post-Injection method at Taizhou Yangtze River Bridge has provided an example and reference for similar projects in the future.     

Taizhou Yangtze River Bridge—the first kilometer level three-pylon two-span suspension bridge in the world

Taizhou Bridge, located at the middle of Jiangsu Province, connecting Taizhou City and Zhenjiang City, started in Dec. 2007. The bridge is the first kilometer level three-pylon suspension bridge in the world, and it adopts longitudinal herringbone shape steel middle pylon for the first time in the world. The foundation of the middle tower is the deepest underwater caisson in soil on earth. A great many of technical innovations such as the design techniques of three-pylon suspension bridge,precisely locating and bottom-sealing techniques of the large scale caisson foundation, manufacturing, combination techniques of steel and concrete in the middle tower, welding of extra thick steel plate, manufacture and control techniques of abnormal sections of the middle tower and so on were introduced.     

鄂尔多斯景观大桥钢塔施工技术

从钢塔制造方案、钢塔分段、钢塔施工等方面介绍了鄂尔多斯景观大桥钢塔施工技术。     

基于ANSYS的主塔施工阶段静风受力分析

帆型桥体造型优美,倒映在水中的桥影恰似一艘帆船,给人以简约大方,迎风前行的感觉。某斜拉桥在横向桥采用单柱式塔型,纵桥向采用了帆型桥塔,主塔迎风面积较大,风对帆型结构产生的侧向推力也较大,有必要对桥塔施工过程进行抗风分析。为验算某斜拉主塔施工过程中,桥塔抗风是否符合安全要求,本文利用有限元程序ANSYS对其中三个工况进行分析计算。在模型中设置横撑和拉杆,对比有无横撑和拉杆对桥塔的影响,为工程施工提供参考依据。验算不均匀风速对帆型桥塔的影响,为结构设计提供参考依据。     

Construction and alignment control of the middle steel pylon of Taizhou Bridge

In this paper, the general construction procedure of the steel middle pylon is briefly introduced. The alignment control of the pylon is carried out during the whole process of the construction. The control concept is extended to the manufacture stage. The manufacturing alignment errors are strictly controlled in the segments precast process in factory, and the errors are recognized and predicted precisely during the installation stage. The adjusting joints are employed to amend the accumulated errors, which ensure that the steel pylon alignment could satisfy the precision requirements after installation.     

混合梁斜拉桥索塔与下横梁异步施工控制分析

某特大桥索塔采用钻石型混凝土索塔,索塔总高度为177.91 m,在下塔柱与中塔柱相交位置设置一道下横梁。施工中塔柱与下横梁采用异步施工,即先将中塔柱施工到第二节段再进行下横梁施工。期间,索塔会出现悬臂状态,故索塔的薄弱截面易出现拉应力,这在桥梁施工中是要避免的,为此,先通过模拟分析异步施工过程对索塔的影响,给出相应的施工控制措施。     

Research on key technologies in design of middle pylon of Taizhou Bridge

At the middle pylon of a three-pylon two-span suspension bridge, the effect of unbalanced loads on the adjacent spans may result in a series of technical bottlenecks in design, such as stability and anti-slippage between saddles and main cables. This article presents the researches conducted on structure selection and behavior characteristics of middle pylon, interaction mechanism between main cables and saddles and their anti-slippage safety performance, elastic and plastic stability analysis and safety assessment of steel middle pylon, and fatigue design load and method for steel pylon of Taizhou Bridge. According to the research results, a longitudinal inverted Y shape steel middle pylon is used in design, effectively solving many technical difficulties, and this type of pylon has become a suitable middle pylon structural form for many three-pylon two-span suspension bridges.     

Research on dynamic characteristics model test scheme for middle pylon of multi pylon multi span suspension bridges

Multi-pylon multi-span suspension bridge is a new type super flexible structure system, and the rigidity design of middle pylon is one of the main difficult technical issues. Due to the requirements of longitudinal rigidity, the structural form and the corresponding foundation type of middle pylon are different from those of the ordinary steel pylon, and the complicated dynamic characteristics make the calculation quite difficult. In this article, exploration has been made in selection of similarity ratio, selection of model materials, section simulation, restriction conditions simulation, fixing of mass blocks, fabrication scheme and testing method by taking into account different construction and working conditions such as restriction conditions and working environment of a 3-pylon suspension bridge, to conduct the test experimental design of the dynamic behavior of the middle pylon, with the purpose to reveal its dynamic characteristics and make comparison and analysis with theoretical assumptions, to provide basis for anti-wind and anti-seismic design and as a reference for the design and research of 3-pylon 2-span suspension bridges in the future.     

Comparison of seismic capacity/demand ratios of two kinds of foundation schemes of Taizhou Bridge

Pile group foundation and caisson foundation are two common foundation schemes of long-span bridges, and the seismic performances of the two kinds of foundations are different. Taking Taizhou Bridge as an example, which is the first kilometer level three-pylon two-span suspension bridge in the world, two foundation schemes are designed for the middle pylon, and two whole bridge models with two different foundation schemes of the middle pylon are established respectively in this paper. The effects of foundation-soil interaction are simulated by equivalent linear soil springs whose stiffnesses are calculated according to m method. Seismic capacity/demand ratios of the two models are calculated. The following conclusions can be drawn: the weak positions of the two schemes are not the same; if caisson foundation is adopted for the middle pylon, the weak position is the bearing capacity of the middle pylon foundation, while if pile group foundation is adopted for the middle pylon, the weak position is the bearing capacity of the side pylon foundation.     

塔底铰接型独塔斜拉桥施工阶段力学特性分析

为了研究塔底铰接型独塔斜拉桥施工阶段的力学行为,通过有限元软件建立空间梁格的数值模型,研究了该结构在各个施工阶段桥塔、主梁的位移、内力和应力变化情况,并对塔底铰接和固结两种设计方案的整体力学行为进行对比分析。结果表明:桥塔最大弯矩位置随着施工阶段不同斜拉索的张拉而发生改变;张拉主梁拉索时,主梁曲率半径外侧受拉,内侧受压;塔底铰接对结构整体受力更加有利。可见塔底铰接型独塔斜拉桥与常规斜拉桥施工阶段的力学行为不同,研究结论可以为未来类似结构的设计、施工和监控提供参考。     

苏通大桥挑战与创新

由于复杂的气象条件和地理环境,建设苏通大桥是一个巨大的挑战.苏通大桥采用2.85m大直径工程钢护筒作为支撑桩成功搭设施工平台,将平台误差控制在5cm以内,将100m长桩的倾斜度控制在1/200以内;将临时结构钢套箱用作防船撞结构,有效解决桥墩防撞安全问题;采用集中控制的千斤顶群顶技术实现了双向潮汐河段6000t钢套箱整体沉放,同步误差控制在1cm以内;采用临时防护与永久防护相结合的冲刷防护方法,有效抑制河床冲刷,保证了基础施工和运营安全;采用温度与风修正和追踪棱镜法解决了索塔施工测量与控制难题,提高了复杂条件下高耸结构施工测量工效,将300m索塔施工误差控制在10mm以内,倾斜度控制在1/40000以内.     

Design of steel box girder for Taizhou Yangtze River Highway Bridge

Taizhou Yangtze River Highway Bridge is the first three-pylon two-span suspension bridge in China. The main girder adopts flat steamline steel closed box girder which has well wind-resistant capability and is technically mature besides beautiful appearance. Straight web plates of the steel box girder in longitudinal direction are proposed in order to ensure the integrity of the steel box girder, and to keep the stress of the steel box girder continuous in the middle pylon, as well as to reduce the gradient of the middle pylon columns. The cross section of the box girder has one box with three cells. Solid-web diaphragm plate with good integrity and high torsional stiffness is adopted. The lifting lugs are utilized in the anchors of suspender cable. In this paper, selection of the cross section of the steel box girder, the general structure design, local structure design and main structure calculation results of Taizhou Yangtze River Bridge are introduced emphatically.     

Study in the design and manufacture process ofthe elastic cable anchor box in steel box girder of Taizhou Bridge

Taizhou Yangtze River Highway Bridge is a large span suspension bridge with three pylons. The elastic cables are installed to connect the steel tower and the steel box girder. The constraints can increase the safety coefficient of the middle saddle, and improve the stress conditions of the middle pylon and decrease the deflection in the middle of the main girder, as well as the longitudinal displacement of the main girder caused by live loads. The anchorage boxes of the elastic cable are installed in the wind fairing outside the vertical web plate of the box girder. Two anchor boxes form a pair and are arranged parallelly. Eight anchor boxes are installed in the bridge. In this paper, the design scheme and the technical difficulties in manufacturing are briefly discussed with the precision control techniques.     

斜拉桥异型主塔稳定性研究

斜拉桥体系中,主塔是受压构件,对于异型主塔,结构重心偏离中轴线位置,空间受力和稳定性比较薄弱,稳定性分析显得极其必要．针对长青沙二桥施工过程中主塔的不同状态,建立主塔有限元分析模型进行稳定性分析;在悬臂施工阶段对比主塔稳定性计算方法,确定了斜拉索保向力对主塔稳定性的贡献．     

Technology for long cable erection of a thousand meter scale cable stayed bridge

In the background of the construction of Sutong Yangtze River Bridge （ short as Sutong Bridge ）, the cable construction method and techniques of a thousand-meter scale cable-stayed bridge are introduced. Some key construction techniques, such as outspreading cable on deck, installing cable at pylon, pulling and fixing cable at the attachment with decks and cable PE sheath protection are discussed.     

Wind tunnel study on wind induced vibration of middle pylon of Taizhou Bridge

Full aero-elastic model tests are carried out to investigate wind-induced vibration of middle steel pylon of Taizhou Bridge. Model of the pylon under different construction periods is tested in both uniform and turbulent flow field. And the yaw angle of wind changes from transverse to longitudinal. Through full aero-elastic model testing, wind-induced vibration is checked, which includes vortex resonance, buffeting and galloping. Vortex resonance is observed and further studies are carried out by changing damping ratio. Based on wind tunnel testing results, wind-resistance of middle pylon is evaluated and some suggestions are given for middle pylon’s construction.     

长沙洪山大桥桥塔倾角对其成桥状态的影响

长沙洪山大桥是一座无背索斜塔竖琴式斜拉桥,跨度206m,建成后将居同类型桥世界第一,其成桥线型受到许多因素的影响,主要分析了斜塔倾角这一因素的影响作用。     

钢锚箱连接对索塔锚固体系受力性能的影响

 为明确多节段钢锚箱式索塔锚固体系的传力机理,以杭州湾跨海大桥北通航孔桥为例,采用有限元分析软件(ANSYS11.0),研究了钢锚箱之间连接与不连接两种方式对索塔锚固体系受力性能的影响。结果显示,钢锚箱之间是否连接对锚固体系各节段以及节段内各构件承担的水平力影响较小,对各节段整体承担的竖向力无影响,而对各节段钢锚箱及塔壁承担的竖向力影响较大;钢锚箱之间是否连接对钢锚箱板件应力、混凝土塔壁应力以及栓钉剪力的分布规律具有明显影响,与钢锚箱不连接体系相比,钢锚箱连接体系各构件的应力或剪力分布更为均匀。     

Key technology and innovation of Sutong Bridge

Sutong Bridge is a cable-stayed bridge across Yangtze River with the main span of 1088m. This article outlines technical challenges, key technology and innovation in the design and construction such as scour protection, lowering steel cofferdam, construction platform establishment, construction and control of pylons, fabrication and damping of long cables, erection and control of steel box girders.     

悬索桥施工过程钢桁梁应力控制分析

悬索桥施工过程中,钢桁梁线形随主缆的大位移不断变化;同时伴随着钢桁梁受力的增加和结构刚度的增加。钢桁梁杆件应力在这些因素的影响下,往往施工过程应力要比成桥状态应力大许多。同样不同的施工顺序和方法在施工过程中对钢桁梁杆件应力的影响也是不同的。通过对矮寨悬索桥钢桁梁新施工方法过程中杆件应力监控来分析钢桁梁杆件应力在施工过程中的变化规律。并和坝陵河大桥施工过程中钢桁梁杆件应力进行比较分析。为新施工方法完善和积累经验奠定基础,也为以后钢桁梁杆件的设计和施工方案的选择提供参考。