Comparative life-cycle analysis of steel-concrete composite bridges

Competitiveness of steel construction and, in particular, steel and composite bridges, requires a broader view that encompasses the concepts of sustainability and life-cycle assessment in parallel with the classical structural and geotechnical issues. Also, from the economical viewpoint, the progressive transfer of operational duties from the National Road Authorities to private companies in the context of design, build and operate contracts, reinforces the need for an integrated approach.It is the purpose of the present paper: (i) to present an integrated methodology for a life-cycle and sustainability analysis (LCA and LCCA); and (ii) to apply such an integrated approach to a case study of a composite bridge. The proposed approach, besides structural considerations, contemplates environmental aspects (energy consumption, raw materials, and environmental impacts), economical aspects and a brief discussion of degradation and maintenance aspects. The case study consists of a three-span continuous bridge with spans of 27.2 m + 35.0 m + 27.2 m, thus totalling 89.40 m. Finally, some comparisons are presented between alternative solutions.     

某商业综合体大跨度钢结构连廊吊装技术

浙江省杭州市某商业综合体结构形式为钢筋混凝土框架结构,2幢综合体之间采用钢桁架连廊连接.该钢结构连廊具有构件跨度大、桁架高度高、吊装高度高、单榀桁架重等特点.通过对比分析分段自承式和高空悬挂式散装吊装方案的施工流程和力学性能,同时采用有限元软件分析主要受力构件安装应力分布和关键节点处弯矩值变化情况,最终选用高空悬挂式散装施工方案.     

广州亚运会主场馆大跨度悬挑顶篷主体钢结构施工技术

广州亚运会主场馆顶篷钢结构为悬挑68m的空间组合管桁架结构体系,对其主体钢结构施工技术进行研究和解析.首先根据现场情况对工程施工情况进行了总体策划,通过结合工程本身结构特性、施工现场的特点,合理划分施工区域、选取合理的施工方法以及施工机具,解决了看台钢结构吊装施工和屋面顶篷钢结构安装问题,取得了良好的效果.     

97m高空大跨度钢桁架安装技术

某单层大跨厂房,钢屋盖由10榀桁架组成,安装高度97m,桁架跨度30m,主要截面形式为H型钢.该钢结构屋盖施工高度高、构件长度长、质量大、施工作业面小.根据结构特点,采取在桥架大梁安装临时支撑架的措施辅助桁架安装.详细介绍了屋盖钢桁架拼装的测量控制.     

沈抚新城“生命之环”三角形桁架自平衡索具吊装技术

异形钢结构在施工过程中,存在着起吊、定位、固定难等特点。沈抚新城"生命之环"主体结构主要为混凝土基础和三角形变截面钢管桁架组成的环状结构体系,分段构件采用现场胎架整体拼装,大型履带式起重机起吊回直,并通过相关措施调节至吊装角度,安装到位并固定。本工程特制的自平衡系统索具很好地解决了构件体型大、截面异形、重心难确定等问题。重点介绍了该索具的工作方式及其吊装角度调整。     

哪吒大桥主索鞍顶推施工控制研究

哪吒大桥为钢桁加劲梁悬索桥,桥塔设计为钢筋混凝土门式塔,施工过程中采用主索鞍顶推施工法进行索塔纠偏.计算并确定主索鞍顶推时机和顶推量,并通过实测施工中索塔应力和偏位,按照以索塔应力控制为主、索塔偏位控制为辅的调整方案,结合具体的施工情况对主索鞍各阶段顶推量进行修正.通过分析顶推过程中索塔受力和偏位情况,并对比分析拟定顶...     

SINO大型磨机吊装施工模拟分析

SINO大型磨机具有体积大和质量大的特点,根据钢管桁架刚度形成过程,基于有限元理论,对磨机吊装施工进行数值计算分析,并将施工现场动态监测值与数值计算分析进行对比。研究表明:该数值模拟方法是有效和准确的。在数值模拟计算的依托下工程顺利完成,证明该数值模拟方法可靠合理。     

太原南站大跨度放射伞状空间桁架分块安装技术

太原南站站房屋盖工程共由48个独立伞状钢结构单元体构成,每个钢结构单元体由1个钢柱、4榀主桁架和若干次桁架构成。采用大跨度放射伞状空间桁架的分块安装技术,将单元体拆分为若干个分块,各个分块在地面拼装完成,吊装时按钢柱、柱顶分块、主桁架分块、次桁架分块、嵌补杆件的顺序进行。吊次和高空操作大大减少,提高了安装效率和质量。     

重庆粉房湾大跨度双层桁架桥制作与安装技术

重庆粉房湾大桥主桥采用桁架和正交异性桥面板组合体系,其具有结构新颖、栓焊结合、锚箱独特等结构特点,以及跨度大、双层桥面、塔梁交叉作业、工期紧等安装特点。通过研究,采取了针对性的解决措施。主桥制作时,将钢桥阶段的构件合理拆解成小制作单元,按照"单元制作,阶段成型"的方法。重点介绍了钢桁梁制作、桥面块体制作、焊接变形控制及焊缝抗疲劳性能等制作技术,及顶推滑移、对称悬拼等安装技术。     

上海虹桥综合交通枢纽楼前高架大吨位钢桥面滑移技术

在上海虹桥综合交通枢纽楼前高架工程中,经过方案比选,利用一种钢-混凝土组合桁架结构作为滑移支撑体系,完成大吨位钢箱梁桥面的滑移。该方案在混凝土梁中间设立杆,混凝土柱顶埋设埋件,初始状态立杆底部与混凝土梁顶面预留间隙,这样既解决了因场地限制不能吊装的难题,又可以利用自身结构释放内力,减小对下部结构的影响,从而改善整体结构受力。     

施工控制在大跨空间桁架中的应用

青岛大剧院钢屋盖为大跨空间钢桁架结构体系,跨度达78.4m,屋面造型对桁架变形要求极高.为解决钢桁架施工过程中挠度及内力不易控制的难题,把全过程仿真分析、施工监测以及自适应控制理论应用到大跨空间桁架的施工过程中,实现空间桁架的施工控制.实践表明,空间桁架的施工控制既可以使结构内力和标高与设计值较好地吻合,又可以确保施工过程的安全.     

成都新世纪环球中心对三角形格构式提升架的设计和应用

根据结构形式和现场条件,传统提升施工的提升架一般为悬挑梁式和门式提升架。结合成都新世纪环球中心中央游艺区拱形钢结构屋盖的结构特点,介绍了对三角形格构式提升架的设计思路、提升架的形式及提升架设计方法等。以屋盖3为例,建立提升架计算模型,结果表明,提升架顶端变形满足规范要求。同时指出对三角形格构式提升架使用中的注意事项:加强提升架基础顶面配筋、保证落地端节点刚度、控制提升架垂直度等。     

Development of Brazilian steel construction

This article presents a concise short overview of the development of the steel industry in Brazil, with the emphasis on civil construction. The relatively rapid increase in the application of steel structures for both low and tall buildings and the modern bridges in Brazil are the results of an extensive effort of the steel producers and the improvement of steel courses and research programmes in several universities and institutions during the last two decades. The steel industry in collaboration with the universities, which have provided the results of their recent studies, contributed to the improved steel technologies and composite construction. Data, supplied by the Brazilian Institute of Metallurgy, IBS, is presented on the actual steel production and fabrication with regard to application in civil engineering. Case studies of steel structures, such as multi-storey buildings, space structures, light gauge steel construction and bridges, are presented and commented on. Further, steel structures subjected to corrosion or to fire, as well as steel and composite semi-rigid joints, are mentioned and finally the Brazilian experience with steel architecture is introduced.     

Comparative structural response of two steel bridges constructed 100 years apart

This paper presents a comparative numerical analysis of the structural behaviour and seismic performance of two existing steel bridges, the Infiernillo II Bridge and the Pinhão Bridge, one located in Mexico and the other in Portugal. The two bridges have similar general geometrical characteristics, but were constructed 100 years apart. Three-dimensional structural models of both bridges are developed and analysed for various load cases and several seismic conditions. The results of the comparative analysis between the two bridges are presented in terms of natural frequencies and corresponding vibration modes, maximum stresses in the structural elements and maximum displacements. The study is aimed at determining the influence of a 1 century period in material properties, transverse sections and expected behaviour of two quite similar bridges. In addition, the influence of the bearing conditions in the global response of the Pinhão Bridge was evaluated.     

预应力大跨度空间钢结构的应用与展望

本文主要阐述了我国预应力大跨度空间钢结构应用与发展的基本情况。这些顶应力空间钢结构包括有预应力网络结构、斜拉网络结构、张弦梁结构、弓式预应力钢结构等。最后,本文展望了新世纪的预应力空间结构。     

Optimisation model to schedule railway track renewal operations: a life-cycle cost approach

Besides high initial construction costs, ballasted railway tracks also have high investment requirements, related to maintenance and renewal (M&R) works. Decision support tools for railway track components that optimise these works are increasingly gaining in importance. This paper presents an optimisation model that integrates ballast, rail and sleeper degradation models in a mixed integer linear programming model. This model links the decisions to renew these components with their condition and takes advantage of the integrated planning of renewal works to minimise the railway track life-cycle cost (LCC). The practical utility of the model is illustrated with a case study involving the Portuguese Lisbon–Porto line. The results indicate a reduction in track renewal cost if the grouping of components, track segments and time interval for renewal operations are optimised. Furthermore, this paper demonstrates that possible annual budget restrictions for railway track M&R operations can have an important influence on the railway track LCC.     

T形刚构桥墩柱加固综合施工技术

近些年,由于各种原因,桥梁病害情况日趋严重.考虑到造价的影响,对旧结构加固补强往往是很值得推荐和工程上常用的方法之一.在分析桥梁病害和常规加固方法的基础上,结合工程实例,通过工程检测和计算分析,提出了增大截面面积、植筋、施加竖向体外预应力的综合施工技术,并详细介绍了施工工艺和操作要点.结果表明,采用该综合加固技术能有效降低工程造价,缩短工期.     

深圳宝安体育场轮辐式索-桁屋盖整体张拉提升技术

深圳宝安体育场屋盖为轮辐式索-桁结构+膜结构组合形式。屋盖索-桁结构是膜结构的支撑骨架,由上内环索、下内环索、飞柱、外环梁及36片三角形径向索网组成,施工的关键是径向索的整体张拉。钢索数量多、荷载大、工期紧,施工难度非常大。在对各种张拉方案进行仿真模拟计算后,最终确定了先提升上径向索就位,再提升张拉下径向索就位,最后安装悬挂索的张拉方案,并采用计算机自动控制整体张拉系统进行张拉施工。