GMA material design and construction quality control for asphalt pavement of steel box girder: Case study of the Hong Kong–Zhuhai–Macao Bridge

To improve the quality of the Hong Kong–Zhuhai–Macao Bridge paving project,a new paving layer material,Guss-mastic asphalt(GMA),was proposed in this paper by combining the advantages of two types of cast asphalt mixtures:mastic asphalt(MA)and Guss asphalt(GA).Based on the characteristics of GMA,to simulate its actual production process,this study developed a small-simulated cooker mixing equipment.Moreover,the flow degree,60C dynamic stability,and impact toughness were proposed to be used to evaluate the construction and ease,high temperature stability,and fatigue resistance of GMA cast asphalt mixtures,respectively.Moreover,the quality control standards for GMA paving materials by indoor tests,field trial mix GMA material performance tests,and accelerated loading tests were finalized.The study showed that the developed simulated cooker yielded consistent mixing results in the same working environment as the engineering cooker device.Increasing the coarse aggregate incorporation rate,coarsening the mastic epure(ME)gradation composition,and using a smaller oil to stone ratio can reduce the flowability of the GMA materials to varying degrees.The four-point bending fatigue life and impact toughness of the different GMA materials are correlated well.A mobility of<20 s,60C dynamic stability of 400–800 times/mm,15C impact toughness of400 N⋅mm,and cooker car mixing temperature control standard of 210C–230C form an appropriate control index system for the design and production of GMA cast asphalt mixtures.Simultaneously,accelerated loading tests verified the accuracy and reliability of the quality control index system that has been used in the GMA paving project of the Hong Kong–Zhuhai–Macao Bridge deck and has achieved good application results.

Study in the design and manufacture process of the 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.

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.

Discussion Based on Formwork Construction of Box Girder Formwork Design Scheme

Formwork construction has been the important and difficult of the construction process, so the design plan is very important. This paper relies on the Shun Ping Yu subordinate Fertgbo bridge rebuilding project, detailing the cast-in-place box beam formwork support system safety special construction plan, focuses on box girder formwork design scheme of foundation design, box girder bracket design and box girder formwork design, to provide a reasonable reference for similar projects.

Research on Construction Process of Steel Box Girder Bridge and Its Stress Analysis

The paper introduce the construction method of large segment hosting and its difficulty, and drawing up corresponding liner and stress monitoring plan. The paper gives the calculation method of shear area for such a big cantilever thin-walled steel box girder section, namely the shear coefficient computation theory of Professor Hu Haichang, and the use of this shear area perfect beam element model, structure model and the experiment prove that the shell model is more consistent, given a certain reference for similar section project.

Geometric state transfer method for construction control of a large-segment steel box girder with hoisting installation

This paper aims to address the problem of geometric state control of large-segment steel box girders in offshore hoisting during the construction of large-span bridges. First, the geometric state control indexes of a large-segment steel box girder are determined, such as the manufacturing parameters of the top and bottom slabs, the width of the annular joint, and the support position. Second, the geometric state equations and state transfer matrixes of large-segment steel box girders under different conditions are deduced by taking the mileage and elevation of control points as basic state variables. In application of the geometric state transfer method in the construction control of the Hong Kong-Zhuhai-Macao Bridge, the width of the annular joint and the position parameters for the support of the large-segment steel box girder are predicted precisely. Moreover, the manufacturing parameters of the top and bottom slabs of the steel box girders are calculated reliably. The measured values show that the width of the annular joint is basically the same with the difference of less than 2 mm, the eccentricity of bridge support is less than 20 mm, and the elevation error of the bridge deck is within-10 mm to +15 mm, which meets the construction accuracy. Using the geometric state transfer method, the rapid and accurate installation of the Hong Kong-Zhuhai-Macao Bridge has been realized, demonstrating that the precise control of the geometric state of a steel box girder with ectopic installation and multi-state transition can be realized by using the geometric state transfer method.

Refined analysis and construction parameter calculation for full-span erection of the continuous steel box girder bridge with long cantilevers

To accurately control the full-span erection of continuous steel box girder bridges with complex cross-sections and long cantilevers, both the augmented finite element method(A-FEM) and the degenerated plate elements are adopted in this paper. The entire construction process is simulated by the A-FEM with the mesh-separation-based approximation technique, while the degenerated plate elements are constructed based on 3D isoparametric elements, making it suitable for analysis of a thin-walled structure. This method significantly improves computational efficiency by avoiding numerous degrees of freedom(DoFs) when analyzing complex structures. With characteristics of the full-span erection technology, the end-face angle of adjacent girder segments, the preset distance of girder segments from the design position, and the temperature difference are selected as control parameters, and they are calculated through the structural response of each construction stage. Engineering practice shows that the calculation accuracy of A-FEM is verified by field-measured results. It can be applied rapidly and effectively to evaluate the matching state of girder segments and the stress state of bearings as well as the thermal effect during full-span erection.

Control measures for thermal effects during placement of span-scale girder segments on continuous steel box girder bridges

In this study, we examined the thermal effects throughout the process of the placement of span-scale girder segments on a 6×110-m continuous steel box girder in the Hong Kong-Zhuhai-Macao Bridge. Firstly, when a span-scale girder segment is temporarily stored in the open air, temperature gradients will significantly increase the maximum reaction force on temporary supports and cause local buckling at the bottom of the girder segment. Secondly, due to the temperature difference of the girder segments before and after girth-welding, some residual thermal deflections will appear on the girder segments because the boundary conditions of the structure are changed by the girth-welding. Thirdly, the thermal expansion and thermal bending of girder segments will cause movement and rotation of bearings, which must be considered in setting bearings. We propose control measures for these problems based on finite element method simulation with field-measured temperatures. The local buckling during open-air storage can be avoided by reasonably determining the appropriate positions of temporary supports using analysis of overall and local stresses. The residual thermal deflections can be overcome by performing girth-welding during a period when the vertical temperature difference of the girder is within 1 °C, such as after 22:00. Some formulas are proposed to determine the pre-set distances for bearings, in which the movement and rotation of the bearings due to dead loads and thermal loads are considered. Finally, the feasibility of these control measures in the placement of span-scale girder segments on a real continuous girder was verified: no local buckling was observed during open-air storage;the residual thermal deflections after girth-welding were controlled within 5 mm and the residual pre-set distances of bearings when the whole continuous girder reached its design state were controlled within 20 mm.

Design and construction of super-long span bridges in China: Review and future perspectives

Super-long span bridges demand high design requirements and involve many difficulties when constructed,which is an important indicator to reflect the bridge technical level of a country.Over the past three decades,a large percentage of the new long-span bridges around the world were built in China,and thus,abundant technological innovations and experience have been accumulated during the design and construction.This paper aims to review and summarize the design and construction practices of the superstructure,the substructure,and the steel deck paving of the long-span bridges during the past decades as well as the current operation status of the existing long-span bridges in China.A future perspective was given on the developing trend of high-speed railway bridge,bridge over deep-sea,health monitoring and maintenance,intellectualization,standard system,and information technology,which is expected to guide the development direction for the construction of future super long-span bridges and promote China to become a strong bridge construction country.

晋江世纪大道大跨径简支钢箱梁上部结构设计

晋江世纪大道南延伸至科院路(南安段)工程奎峰大桥采用单孔跨径66m简支钢箱梁桥上跨主路左、右辅道。本文应用MIDAS对大跨径简支钢箱梁上部结构进行有限元分析,结果表明,结构验算满足规范要求,充分体现了大跨径简支钢箱梁的结构性能及受力特征。前期设计阶段对钢箱梁上部结构往往仅采用杆系模型进行匡算分析,即此阶段仅考虑第一体系受力分析结果,计算结果表明第二体系应力较大,不容忽视。本文大跨径钢箱梁顶、底、腹板、加劲板、横隔板等构造尺寸、布置等细节可为类似的钢箱梁上部结构设计提供参考。

大块件桥梁钢箱梁免吊装快速施工关键技术

市场经济环境下,我国桥梁工程建设水平不断提升,出现了较多桥梁形式。钢箱梁属于较为常见的一种。具有自重轻、强度高等优点,不过在实际施工环节由于钢箱梁块件较大,存在较大的施工难度,需要积极探究有效的技术手段,实现大块件桥梁钢箱梁施工高质量开展。基于此,本文对大块件桥梁钢箱梁免吊装快速施工技术原理进行分析,并结合实际工程,探究大块件桥梁钢箱梁免吊装快速施工关键技术。希望在本文研究下,为相关人员提供参考借鉴,促进钢箱梁免吊装快速施工技术水平持续提升。

南京仙新路长江大桥主桥结构设计

南京仙新路长江大桥主桥为跨径1760 m的单跨钢箱梁悬索桥,主缆垂跨比1/9,边跨跨径580 m,边中跨比0.33。该桥上、下游各设1根主缆,单根主缆由169股127∅5.4 mm镀锌铝高强钢丝索股组成,采用PPWS法施工,钢丝标准抗拉强度2100 MPa。吊索与索夹采用销接式结构,跨中设置柔性中央扣索,短吊索设置关节轴承。主索鞍采用宽鞍槽单纵肋铸焊结合构造,散索鞍采用底座式全铸结构。加劲梁采用扁平流线型封闭整体钢箱梁,总宽31.5 m,梁高4 m,顶板与U肋之间采用双面埋弧全熔透焊接。桥塔采用门形混凝土结构,总高277.3 m,其上横梁为预应力混凝土结构,外包N字造型钢结构;桥塔基础采用直径2.8 m钻孔灌注桩。南锚碇采用外径65 m圆形地下连续墙基础;北锚碇采用沉井基础,平面尺寸70 m×50 m,高50 m。对结构进行静力分析及抗风性能理论和试验研究,结果表明:结构强度、刚度均满足规范要求;在加劲梁上设置0.67 m高中央稳定板、两侧风嘴处设置1 m宽水平稳定板后,大桥的颤振、涡振等抗风性能均满足要求,且具备一定的阻尼储备。

三星堆古蜀文化遗址博物馆大型螺旋坡道结构设计与分析

三星堆古蜀文化遗址博物馆中庭的螺旋坡道采用钢箱梁结构体系,最大半径28.7m,水平投影长度118.5m。介绍了大型螺旋坡道结构体系选型和边界条件的对比过程,采用通用计算软件MIDAS Gen建立多尺度整体模型考虑螺旋坡道和主体结构的相互作用,通过静力分析和反应谱分析考察螺旋坡道在不同荷载作用下的承载能力和变形,并采用有限元软件ANSYS建立分析模型进行连续倒塌分析。结果表明,螺旋坡道采用钢箱梁结构具有较好的整体刚度,静力荷载和地震作用下坡道的应力和变形均满足规范要求,并具有较好的抗连续倒塌能力。

大倾角钢箱提篮拱桥总体设计

考虑施工技术、经济性和景观效果等方面,陕西蔡家坡渭河特大桥主桥采用(35+210+35) m大倾角钢箱提篮拱桥。该桥采用摩擦摆和环向钢丝绳阻尼支座综合减隔震约束体系,以降低结构的地震响应。拱肋为单室等宽钢箱截面,采用主、副拱肋2条悬链线,主、副拱肋共面,设计为横向内倾20°的大倾角,在提高桥梁景观效果的同时,又有效提高了结构的整体稳定性;拱肋设钢-混结合段连接拱脚与混凝土拱座。桥面系采用自重较轻的正交异性钢桥面板结构。吊杆采用抗拉强度1 860 MPa的环氧柔性钢绞线。基础采用Φ2.5 m的钻孔灌注群桩,以抵抗软弱地质条件下荷载的竖向及水平作用力。该桥总体采用先梁后拱的施工方案。整体及局部有限元分析结果表明,桥梁结构力学性能均满足规范要求,设计安全可靠。

波形钢腹板-钢底板组合箱梁耐火极限与设计

研究目的:近年来交通量的增加,由车辆碰撞或易燃物品运输车辆引起的桥梁火灾时有发生,不容忽视。为了解火灾下波形钢腹板-钢底板组合箱梁的火灾响应,采用ANSYS建立三维热-力耦合分析模型,分析火灾下组合箱梁温度场分布状态与抗弯承载力衰变规律,研究不同受火场景对组合箱梁耐火极限的影响,提出抗火设计方法。研究结论:(1)火灾下组合箱梁截面抗弯承载力呈三阶段发展;不同受火范围下跨中挠度随受火时间延长均呈两阶段发展;随着受火长度的增加,组合箱梁挠度增长幅度越大,受火初期受热弯曲效应作用越显著;(2)与抗力准则相比,采用挠度破坏准则判定组合箱梁的耐火极限较安全;(3)在组合箱梁底板增设不同类型的加劲肋形式,均可提高组合箱梁的耐火极限,当加劲肋材料用量相同时,与增设通长加劲肋相比,增设底板局部加劲肋对组合箱梁的耐火极限改善效果更好;(4)本研究成果可为波形钢腹板-钢底板组合箱梁的耐火极限理论分析与抗火设计提供参考。

公铁混合布置大跨度斜拉桥主梁断面形式研究--以赣江公铁大桥西支主桥设计为例

以赣江公铁两用大桥西支主桥设计为例,研究一种适应上层8车道公路、下层对称双线铁路+4车道公路混合布置的主梁断面形式。提出带挑臂双索面箱桁组合断面、带挑臂单索面箱桁组合断面、矩形箱桁组合断面、矩形钢桁梁断面4种主梁断面方案,采用有限元软件分析各方案静动力性能及受力特点,综合考虑方案构造特点、技术指标、工程数量、公铁运营安全、景观效果等,确定该桥选用带挑臂双索面箱桁组合断面。该桥斜拉索最大索力16000 kN,锚固在下层钢箱梁两侧,通过有限元实体分析对锚拉板和钢锚箱式两种索梁锚固形式进行比选研究,钢锚箱形式受力合理、应力水平低、经济性好,设计采用钢锚箱形式。带挑臂双索面箱桁组合断面桥面空间布置合理、下层公铁行车干扰小、梁端竖向变形最小、经济性好,是一种适应公铁混合布置大跨度斜拉桥主梁断面形式。

西十高铁汉江特大桥主桥设计

西十高铁汉江特大桥主桥为主跨420 m的梁桁组合结构双塔斜拉桥,采用半飘浮体系。主梁采用钢桁加劲PC箱梁,梁高3.0 m,桥面全宽17 m。PC箱梁采用C55混凝土,单箱四室等高截面,加劲桁采用渐变三角桁式,材质为Q370qE钢,桁高9.4 m。斜拉索采用标准抗拉强度1770 MPa的镀锌平行钢丝,双索面扇形布置。桥塔采用花瓶式钢筋混凝土框架结构,塔高186.5 m,基础采用∅3 m的钻孔灌注桩,按长短桩设计。结构受力分析结果表明:该桥力学性能指标均满足相关规范要求,整体刚度性能优越,具有良好的颤振稳定性,设置的风嘴能有效抑制涡激振动,采取加劲钢桁上弦杆灌注混凝土、延迟铺轨时间等措施能有效控制主梁的收缩徐变,桥面线形满足铺设无砟轨道的要求。

土耳其1915恰纳卡莱大桥无索区钢箱梁安装关键技术

土耳其1915恰纳卡莱大桥为主跨2023 m的双塔三跨钢箱梁悬索桥。钢箱梁总长3563 m,边跨及桥塔处无索区钢箱梁均为非标准节段,长度为9.8~43.6 m,吊装重量为344~1330 t,涉及多种吊装方式及节段安装工艺,施工难度大。该桥边跨S33节段定位精度要求高、顶推难度大,利用特殊设计牛腿,顺利实现节段顶推及边跨合龙;边跨焊接线形精度要求高、工序转换复杂,S32和S31节段布设临时吊索系统,确保焊接线形可控;塔区工作平台上的S01、T00和M01单个节段利用特殊设计三向可调支架及导向架施工,确保浮吊吊装安全可靠及定位精度可控;S02和M02节段吊装时与已吊装节段在空间上相互干扰,通过布设牵引荡移系统,顺利实现塔区S02和M02节段缆载吊机大角度吊装及节段荡移;采用吊索调节装置、边跨反拉系统及4台缆载吊机同步抬吊等措施,塔区S01、T00和M01组拼焊接的大节段顺利合龙。

某不规则多层长途汽车站结构设计及分析

某不规则多层长途汽车站工程主要由长途客运站、公交首末站、换乘连廊及站台雨棚组成。长途客运站主体结构采用框架-剪力墙结构+张弦梁屋盖。换乘连廊采用单排柱柱顶铰接的排架结构。主要介绍了具有多排斜柱、扭转不规则、楼板大开洞、凹凸不规则等多项不规则的长途客运站的抗震性能设计、屋面张弦梁结构设计;分析了钢箱梁+钢筋混凝土Y形分叉柱的换乘连廊的结构特点;剖析了钢箱梁考虑剪力滞效应和受压局部稳定影响的有效截面宽度的计算及Y形分叉柱与横梁、Y形分叉柱柱墩支座选型的设计要点。分析结果表明,所采取的合理结构设计确保了结构安全。

钢箱梁顶推技术在高速公路跨线桥施工中的应用

为保证高速公路跨线桥施工质量,以通修高速公路项目沙坪东互通立交桥跨越既有杭瑞高速为例,研究钢箱梁顶推技术。结合工程实际情况,设计钢箱梁顶推施工方案,选择630 t步履式平移顶推设备,依据施工标准完成顶推施工关键工序施工,完成钢箱梁的顶推施工。对施工结果分析后确定该技术的施工质量较好,抗倾覆能力的计算结果均在3以上,满足工程标准。