Concrete-Filled Steel Tube Arch Bridges in China

In the past 20 years, great progress has been achieved in China in the construction of concrete-filled steel tube （CFST） arch bridges and concrete arch bridges with a CFST skeleton. The span of these bridges has been increasing rapidly, which is rare in the history of bridge development. The large-scale construction of expressways and high-speed railways demands the development of long-span arch bridges, and advances in design and construction techniques have made it possible to construct such bridges. In the present study, the current status, development, and major innovative technologies of CFST arch bridges and concrete arch bridges with a CFST skeleton in China are elaborated. This paper covers the key con- struction technologies of CFST arch bridges, such as the design, manufacture, and installation of steel tube arch trusses, the preparation and pouring of in-tube concrete, and the construction of the world＇s longest CFST arch bridge-the First Hejiang Yangtze River Bridge. The main construction technologies of rein- forced concrete arch bridges are also presented, which include cable-stayed fastening-hanging cantilever assembly, adjusting the load by means of stay cables, surrounding the concrete for arch rib pouring, and so forth. In addition, the construction of two CFST skeleton concrete arch bridges-the Guangxi Yongning Yong River Bridge and the Yunnan-Guangxi Railway Nanpan River Bridge--is discussed. CFST arch bridges in China have already gained a world-leading position; with the continuous innovation of key technologies, China will become the new leader in promoting the development of arch bridges.

Numerical Simulation Analysis of Welded Joints in Arch Ribs of Large Span Steel Pipe Arch Bridges

In order to study the residual stress distribution law of welded joints of arch ribs of large-span steel pipe concrete arch bridges,numerical simulation of temperature,stress and strain fields based on ABAQUS for welded joints of arch-ribbed steel tubes using 7-,8-and 9-layer welds is carried out and its accuracy is demonstrated.The steel pipe welding temperature changes,residual stress distribution,different processes residual stress changes in the law,the prediction of post-weld residual stress distribution and deformation are studied in this paper.The results show that the temperature field values and test results are more consistent with the accuracy of numerical simulation of welding,the welding process is mainly in the form of heat transfer;Residual high stresses are predominantly distributed in the Fusion zone(FZ)and Heat-affected zone(HAZ),with residual stress levels tending to decrease from the center of the weld along the axial path,the maximum stress appears in the FZ and HAZ junction;The number of welding layers has an effect on the residual stress distribution,the number of welding layers increases,the residual stress tends to decrease,while the FZ and HAZ high stress area range shrinks;Increasing the number of plies will increase the amount of residual distortion.

Recent Construction Technology Innovations and Practices for Large-Span Arch Bridges in China

Arch bridges provide significant technical and economic benefits under suitable conditions.In particular,concrete-filled steel tubular(CFST)arch bridges and steel-reinforced concrete(SRC)arch bridges are two types of arch bridges that have gained great economic competitiveness and span growth potential due to advancements in construction technology,engineering materials,and construction equipment over the past 30 years.Under the leadership of the author,two record-breaking arch bridges—that is,the Pingnan Third Bridge(a CFST arch bridge),with a span of 560 m,and the Tian’e Longtan Bridge(an SRC arch bridge),with a span of 600 m—have been built in the past five years,embodying great technological breakthroughs in the construction of these two types of arch bridges.This paper takes these two arch bridges as examples to systematically summarize the latest technological innovations and practices in the construction of CFST arch bridges and SRC arch bridges in China.The technological innovations of CFST arch bridges include cable-stayed fastening-hanging cantilevered assembly methods,new in-tube concrete materials,in-tube concrete pouring techniques,a novel thrust abutment foundation for nonrocky terrain,and measures to reduce the quantity of temporary facilities.The technological innovations of SRC arch bridges involve arch skeleton stiffness selection,the development of encasing concrete materials,encasing concrete pouring,arch rib stress mitigation,and longitudinal reinforcement optimization.To conclude,future research focuses and development directions for these two types of arch bridges are proposed.

Approach for analyzing the ultimate strength of concrete filled steel tubular arch bridges with stiffening girder

A convenient approach is proposed for analyzing the ultimate load carrying capacity of concrete filled steel tubular (CFST) arch bridge with stiffening girders. A fiber model beam element is specially used to simulate the stiffening girder and CFST arch rib. The geometric nonlinearity, material nonlinearity, influence of the construction process and the contribution of prestressing reinforcement are all taken into consideration. The accuracy of this method is validated by comparing its results with experimental results. Finally, the ultimate strength of an abnormal CFST arch bridge with stiffening girders is investigated and the effect of construction method is discussed. It is concluded that the construction process has little effect on the ultimate strength of the bridge.

Seismic behavior of concrete filled steel tubular arch structures

Shaking table tests of a 1:10 scale arch model performed to investigate the seismic behavior and resistance of concrete filled steel tubular (CFT) arch structures are described in this paper. The El-Centro record and Shanghai artificial wave were adopted as the input excitation. The entire test process can be divided into three stages depending on the lateral brace configurations, i.e., fully (five) braced, two braces removed, and all braces removed. A total of 46 tests, starting from the elastic state to failure condition, have been conducted. The natural vibration frequencies, responses of acceleration, displacement and strain were measured. From the test results, it is demonstrated that the CFT arch structures are capable of resisting severe ground motions and that CFT arches offer a credible alternative to reinforced concrete arches, especially in regions of high seismic intensity.

The New Arched Bridge over Dnipro in Kyiv

The Podilskyi Arch bridge is crossing the Dnipro River in center of Kiev and is part of a 7.4 km long link which connects the center of Kiev with the “sleeping district” on the left bank of the river. The bridge has a main span of 344 m intended for six lanes of vehicles in the top level and two metro lines in the bottom level plus large diameter water pipes. The bridge is of steel, except of the reinforced concrete bases of the lower parts of the arches. The draft design works began in 1991 and in 2005 parallel design and construction work started. Due to the financial crisis in Ukraine, the work was interrupted for several years but construction recommenced in 2018 and the bridge is now planned to be completed in 2020 and the first stage of the transition in 2022.

瓮马铁路乌江特大桥设计关键技术研究

新建瓮马铁路乌江特大桥跨越两山之间深谷,地形复杂、设计难度大。为研究该桥梁方案,首先阐述了主桥的方案构思和结构设计,然后通过空间有限元软件对本桥进行静、动力仿真分析,总结了大跨铁路劲性骨架混凝土拱桥构造和受力特性。结果表明:主跨337 m上承式劲性骨架混凝土拱桥具有刚度大、徐变小、后期养护维修工作量小等优点,主拱圈采用小矢跨比设计,兼顾安全、经济、环保和美观,能够满足铁路桥梁跨越山区“V”形峡谷的要求;主拱圈由劲性钢管混凝土骨架外包C55无收缩混凝土构成,通过分层分段浇筑方案改善拱圈各构件的内力;拱上结合梁采用两片工字形钢与混凝土桥面板相结合的形式,钢梁栓焊结合,便于制造、运输和施工;拱座采用梯形断面扩大基础,基础开挖永临结合,有效降低施工风险;数值分析表明该桥结构的刚度、强度、稳定性均能满足规范要求,能够满足客货共线铁路的安全性和乘坐舒适性要求。可为其他山区铁路桥梁桥式研究提供参考。

车辆荷载作用下钢-混凝土组合梁疲劳应力分析

【目的】随着桥梁服役期延长和车辆荷载增加等多种因素的影响,结构承载力会变得越来越弱,疲劳寿命不断降低,最终可能导致低应力疲劳破坏。因此有必要对车辆荷载下拱桥钢混组合梁的疲劳细节应力进行研究。【方法】采用数值模拟的方法,利用Midas FEA NX软件建立3个标准长度的三维实体精细有限元模型,分析钢混组合梁易损疲劳关键点的位置,并研究车辆荷载横向最不利加载位置和纵向加载下的疲劳细节应力变化规律。【结果】结果表明,组合梁次横梁与中纵梁交点处有三处疲劳关键点;靠近桥梁中线位置是车辆荷载下钢梁疲劳最不利的横向加载位置;四种不同标准的纵向车辆加载时,三个疲劳关键点均出现两次应力峰值,且最大应力幅值均低于常幅疲劳强度的极限值。【结论】研究成果可为钢-混凝土组合梁试验和相关研究提供参考。

曲线条件大跨度拱加劲连续梁设计

贵南高铁二塘双线特大桥采用90m+180m+90m拱加劲连续梁结构。大桥位于曲线上,梁体采用分段直线布置,悬灌施工;主拱采用哑铃形钢管混凝土拱肋,钢管直径1 m,拱肋全高3 m;采用整束挤压钢绞线吊杆,全桥拱设置36组吊杆;纵向活动主墩通过构造措施,形成半刚构结构体系,限制部分梁体问题伸缩变形;大桥采用先悬灌主梁,后在主梁上搭设支架原位拼装拱肋方式施工。经论文研究计算结果表明,该桥刚度、受力等均满足规范要求。

外包钢壳混凝土拱形桥塔节段拼装几何姿态预测研究

赣州市集结大桥主桥为外包钢壳混凝土拱形桥塔斜拉桥,为确保钢混组合拱形桥塔节段拼装精准合龙,采用MIDAS Civil软件建立拱形桥塔空间几何模型,分析外包钢壳和混凝土湿重对桥塔变形的影响,采用切线初始位移法对桥塔施工阶段位移进行预测,通过求解制造线形对桥塔待拼装节段进行预偏修正,并与实测数据进行对比。结果表明:外包钢壳能显著减小桥塔变形;施工阶段桥塔变形主要由混凝土湿重引起,临时支撑能有效减小混凝土浇筑产生的横向变形。基于切线初始位移法的几何姿态预测方法能有效预测桥塔拼装全过程几何姿态,实测成桥阶段桥塔各节段最大偏位为6 mm,小于施工控制要求,具有较高的实施精度,可保证成桥状态下桥塔几何姿态的准确性。

100 m~150 m跨混凝土拱桥基于特定钢拱架的预拱度快速计算方法

针对100 m~150 m跨混凝土拱桥所采用的特定钢拱架的预拱度计算问题,提出了一种用拱圈自重变形和钢拱架变形比值快速计算钢拱架预拱度的方法。为了得到不同矢跨比和拱轴系数下的钢拱架变形比值,编写了通过导入MCT文件建立Midas/Civil有限元模型的辅助程序,实现从单元、边界条件、施工阶段和施工阶段联合截面定义的全过程快速建模,对拱圈混凝土分底板、腹板、顶板三环浇筑,考虑钢拱架与拱圈的联合作用,给出了钢拱架预拱度计算公式。计算结果表明,对于常用矢跨比和拱轴系数的混凝土拱桥,拱圈分环浇筑变形与拱圈自重变形比值的平均值为4.37~4.88,为方便钢拱架弹性变形计算,建议变形比值统一取5.0。将该方法应用于一座净跨径为135 m的混凝土拱桥钢拱架预拱度计算中,得到的钢拱架弹性变形与空间模型结果最大误差为4.30%,满足工程精度要求,表明该方法合理可行,可在混凝土拱桥钢拱架预拱度计算中推广应用。

不均匀温度场下钢管混凝土拱桥管内混凝土脱空分析

为了解不均匀温度场作用下钢管混凝土拱桥管内混凝土脱空原因,依托高原山区某跨径430 m的钢管混凝土拱桥,进行强辐射、大温差联合作用下拱肋拱顶节段足尺模型试验,分析模型温度场分布,并对该不均匀温度场作用下管内混凝土脱空机理进行研究。结果表明:钢管混凝土拱桥水化阶段和运营阶段径向温度场可简化为多段式折线变化规律。14:00时刻,水化阶段温度沿竖直径向(从向阳侧至背阳侧)先减小后升高再减小,在距向阳侧界面D/8~3D/8处(D为钢管内径)存在一个大温差面,运营阶段温度沿竖直径向(从向阳侧至背阳侧)呈先减小后不变再增加的非对称分布规律,从钢管混凝土界面至距其D/8处温度变化大。混凝土水化阶段和运营阶段管内混凝土脱空机理为:在温度场作用下钢管混凝土界面最大纵向应力差分别高达82.6 MPa和61.95 MPa,最大界面径向拉应力分别为0.8 MPa和2.06 MPa,均超过钢管和混凝土间的粘结强度。

基于零位移与无应力状态控制的斜拉扣挂施工扣索力确定方法

大跨度拱桥常采用斜拉扣挂法开展拱肋施工,但在节段拼装过程中扣索索力和拱肋空间位形之间互相影响,索力优化计算以及扣索状态控制问题复杂。提出改进零位移法结合无应力状态控制法的复合扣索力计算方法:基于改进型零位移法快速得到满足成拱线形要求的扣索力大小,基于成拱索力采用无应力状态法反推各施工阶段扣索索力。该复合方法可避免传统零位移法扣索力不准和反复迭代计算的缺陷,施工中扣索可实现一次张拉,后续节段拼装中无需对扣索进行索力调整。以某跨径430 m大跨度钢管混凝土拱桥缆扣合一施工为工程应用背景,采用的零位移法结合无应力状态法对大跨度非对称式钢结构拱肋进行斜拉扣挂拼装的扣索力求解和施工模拟。分析拼装过程中扣索力变化规律,并对比验证实际线形与目标线形偏差,以及拱肋应力与设计应力之间偏差程度。结果表明,所提出的复合算法理论简单且索力求解计算便捷。所求的扣索力可有效保证拱肋拼装完成及松索后拱肋线形和受力均满足要求。

不同连接构造的预制拼装钢管混凝土桥墩数值模拟与地震响应特点

无黏结预应力节段拼装钢管混凝土桥墩主要包括承插连接与混合连接两种承台连接方式。为比较两种不同连接构造下桥墩的地震响应特点,采用OpenSees软件分别建立了桥墩有限元模型,其中,承插连接钢管混凝土桥墩模型能够考虑插入承台部分钢管与周围混凝土的黏结滑移、钢管局部屈曲以及屈曲后撕裂等过程,而混合连接钢管混凝土桥墩模型能够再现出接缝的摇摆行为;并通过与相关拟静力试验数据结果进行对比,验证了两种数值模型的有效性;随后,以一座4跨连续梁桥为背景,分别研究了采用混合连接、无预应力承插连接和预应力承插连接桥墩桥梁结构在地震作用时的响应特点。结果表明:两种承插连接桥墩的墩底钢管在地震动峰值加速度(peak ground acceleration,PGA)约0.4 g时发生屈曲,并伴随水平刚度下降和残余位移增大,且配置无黏结预应力的承插连接桥墩钢管屈曲引起的损伤程度更大,随着地震动输入进一步增大,预应力为桥墩提供的自复位能力逐步增加,在PGA=0.6 g时,预应力承插连接桥墩的残余位移仅为无预应力桥墩的62%。此外,配置混合连接桥墩的桥梁在地震作用下损伤较小,残余漂移比小于0.2%,比承插连接桥墩更优的自复位能力。

大跨度双联连续钢管混凝土拱桥结构体系设计研究

为研究大跨度双联连续钢管混凝土拱桥的合理结构体系及中央拱座合理刚度,以主跨2×405 m渝湘复线双堡特大桥为背景,采用MIDAS Civil软件建立全桥有限元模型,分析考虑自重、汽车荷载和基础沉降作用下,拱桥刚接、铰接、半刚性连接约束体系和不同中央拱座刚度对桥梁力学性能的影响。结果表明:自重、汽车荷载和基础沉降作用下各结构体系力学性能均满足规范要求。双刚接方案拱肋变形对称,结构受力良好,且构造简单、施工方便。中央拱座刚度从0.8 EI(EI为原设计方案中央拱座截面刚度)增加至2.0 EI,自重产生的最大变形基本不变,最大拉应力减小了0.33%,最大压应力减小了0.47%,结构力学性能改善效果不明显。双堡特大桥结构体系推荐采用双刚性连接,中央拱座合理刚度取值为0.8 EI,全桥有限元计算结果表明,该结构体系的强度、刚度、稳定性均满足规范要求。

几何初始缺陷与初应力对钢管混凝土拱桥的影响研究

为探讨拱圈拱轴线的几何初始缺陷和钢管初应力对拱桥结构内力与应力的影响,基于实际工程案例,建立了4个有限元模型,分为2组,一组包括2个模型,考虑了拱轴线的几何初始缺陷影响;另一组也包括2个模型,首先考虑拱轴线几何初始缺陷,然后在此基础上考虑初应力影响,进行拱桥内力和应力分析对比。结果表明:几何初始缺陷对拱圈轴力影响较小,增幅<1%,但对拱圈的弯矩和应力分布影响较明显,特别是在拱顶部分,在拱顶处弯矩减小高达91.31%,而拱脚处增加17.03%,拱脚和拱顶上缘的混凝土应力增加23.19%,下缘的混凝土应力减小51.95%;考虑初应力影响后,拱桥内力分布发生显著变化。拱脚处轴力增加65.5%,拱圈弯矩最大减小68.21%,拱圈截面上缘应力增加幅度高达113.7%。因此,实际施工阶段,必须充分考虑拱圈拱轴线几何初始缺陷影响,并根据实际施工顺序准确模拟初应力。

山区大跨拱桥BIM技术的应用研究

为保证山区大跨钢管混凝土拱桥的建造质量,实现山区拱桥从设计到构件制造施工的一体化建造技术,以白水河特大桥为依托,利用BIM技术进行大跨径钢管混凝土拱桥梁参数化设计,通过BIM正向设计,改变传统的二维设计模式和翻模模式,直接通过三维模型输出施工图;将BIM模型传递至钢结构制造、施工阶段,打通设计、深加工图到工厂构件加工的各环节。对特大桥领域工程的数字化发展进行了探索与创新,对比传统二维设计模式,BIM正向设计图纸在同类桥型中后期调整情况减少80%,有效减少加工废料的产生;在提升山区大跨径拱桥的设计、建造品质的同时缩短了设计、建造周期,为同类型桥梁的建造提供借鉴。

张吉怀铁路酉水大桥非对称拱桥钢拱肋架设技术研究

张吉怀铁路酉水大桥主桥为主跨292 m的非对称上承式钢管混凝土拱桥,其钢拱肋采用斜拉扣挂法进行节段悬臂架设施工。本文结合张吉怀铁路酉水大桥工程,针对高速铁路非对称拱桥钢拱肋安装施工技术展开研究,主要包括:复杂地形条件下的施工技术,因地制宜地进行缆索起重机的设计及安装,钢管拱整节段拼装和架设,合龙装置和技术等。该施工技术保障了钢拱肋架设的精度和质量,钢拱肋的成拱线形与设计值较为吻合。该桥运营以来,各结构性能指标均满足设计要求。

钢管混凝土系杆拱桥吊杆连锁破断力学性能研究

通过有限元软件建立某下承式钢管混凝土系杆拱桥空间分析模型,建立评价标准分析桥梁结构各组成部分的响应,对拱桥发生吊杆破断连锁反应过程中结构力学性能进行研究。结果表明,仅跨中2根吊杆破断即有可能引发后续吊杆破断连锁反应。在吊杆破断连锁反应过程中,系杆梁与桥面会先于拱肋发生破坏;吊杆破断连锁反应不足以引发结构失稳,发生单侧吊杆破断连锁反应后结构破坏形式为桥面系与拱肋破坏的局部垮塌。

双跨连续拱桥缆索吊装系统设计及计算分析

以某世界在建最大跨2×405 m的上承式双跨连续拱桥为工程背景,详细介绍了其缆索吊装系统设计并利用有限元程序MIDAS/civil对其缆索吊装过程进行了仿真分析,实测结果表明:采用“过程最优,结果可控”扣索一次张拉施工优化计算方法来进行施工控制计算,可将拱肋松索后拱圈线形与目标线形的线形偏差控制在24 mm内,实际扣索张拉力与理论扣索张拉力最大误差控制在9%以内,计算精度较高。