中国铁路钢桥的发展历程及展望

针对中国不同时期建造的铁路钢桥及相应的设计、建造背景,阐述了中国铁路桥梁发展的辛酸历程,提出了铁路钢桥仍需解决钢材高强、车桥耦合共振、大跨度带来的一系列振动等关键技术问题。最后,指出建造铁路钢桥的核心问题是钢材料品质、建造技术及相应的机械设备。实践证明,中国铁路桥梁建设已经取得了巨大的成就,但要成为世界桥梁设计、建设的领头羊仍需加倍努力。     

Employment and income loss in a Steel City

Abstract

Post war economic activity in the Wollongong region has depended largely upon a manufacturing base in general and on the production of iron and steel in particular. The combined effects of recession and restructuring in the steel industry has created severe adjustment problems for the region.

This paper examines the impact of recent job loss in the steel and other manufacturing industries upon employment and income within the Wollongong region by the use of a regional input-output table supplemented by survey data.     

Design of Rupture Strength of Side Blocks in Elevated Steel Girder Bridges with Elastomeric Bearings

Elastomeric rubber bearings with side blocks have been extensively used as a seismic response-control device in steel girder bridges in Japan. In real scenarios, the behavior of the girder bridges with elastomeric bearings are usually complex because of the complex mechanism by which the seismically induced inertia forces at concrete deck transmits to the girder bearings. Therefore, it is important to carry out seismic response analysis of a whole bridge system considering the interaction between different structural components in order to check the performance of the side blocks during an event of severe earthquakes. The objectives of the present study are to develop a detailed three-dimensional finite element (FE) model of an elevated girder bridge system and to propose a design rupture strength for the side blocks. The FE-model is constructed based on an existing plate girder bridge considering the effect of concrete slab, girders, stiffeners, rubber bearing, pier and the damage control by the side blocks. A sequence of seismic response analysis is then performed using four different rupture forces of the side blocks by considering the Level-2 design earthquake, the 1995 Kobe earthquake and the 2016 Kumamoto earthquake. The analytical investigation reveals that the side blocks should be designed to withstand a horizontal force of at least 1200 kN in order to prevent the rupture of the side blocks and to mitigate damage of bridge piers. Moreover, the damage to the critical parts of bridge superstructure can be mitigated by strengthening the side blocks. Based on the analysis results, a retrofit plan to strengthen the side blocks of existing girder bridges is proposed.

     

A Bridge Management System for Elevated Steel Highways

The Hanshin Expressway network extends some 200 km, forming the traffic arteries of the heavily urbanized Hanshin area surrounding Osaka, the second largest city in Japan. Due to restrictions on construction in mature cities, 93 percent of the total length of this network is elevated, and 77 percent of the elevated structures use steel girders that have numerous curves to allow complicated road alignments. These elevated structures are showing signs of damage after serving for almost 30 years under chronic overload conditions. This article describes the various types of damage that are frequently detected in elevated steel bridges and, focusing on typical fatigue-induced damage, reviews the repair process that begins with the investigation of causes and potential repair methods and continues through the implementation and inspection of the repair work. Propositions are presented that may enable the design of more durable steel bridges. In addition, this article briefly discusses a database system that is being used for the maintenance and management of steel bridges.     

钢桥施工技术(一)

钢桥施工技术应包括下部结构施工、上部结构施工两部份,这里下部结构施工从略,上部结构施工指梁、拱圈、索等钢结构施工技术。总体讲在大跨度桥梁施工中,钢桥施工要比预应力钢筋混凝土桥轻盈和方便,这主要得利于构件轻,而构件轻又是高强度、高弹性模量所致。一、钢梁拱圈的施工一般对于梁,拱圈的施工可归纳为以下几种方法:a)支架法;b)顶推法(对于钢桥可为伸臂法、钓鱼法、浮运法);c)旋转法;d)悬臂法;e)大型设备施工法等诸方法     

Characterization of fatigue properties of ASTM A709 high performance steel

Because of its superior toughness, strength and weldability, high performance steel (HPS) has gained increasing popularity for use in highway bridges. Its fatigue resistance, however, is not yet well characterized. To study the fatigue behaviour of HPS, an analytical method that can predict both fatigue crack initiation and propagation is desirable. The use of established and proven analytical methods, coupled with a material-based testing programme, provides a sound and cost effective approach to developing fatigue design curves for HPS. Of the various methods of fatigue life prediction available, strain-based and energy-based methods seem to be the most promising. In order to obtain the necessary material input parameters for the proposed methods, and also to better understand the properties of HPS, material tests were conducted on ASTM A709 HPS 485W steel and on a conventional structural steel with a more typical toughness level to characterize their monotonic and cyclic material properties. Because of its higher strength, HPS 485W steel exhibits a slightly higher fatigue resistance in the high cycle fatigue region for non-welded details compared to steels of lower strength and toughness.     

初始荷载下中空钢管混凝土柱轴向强度

与传统的钢管混凝土柱相比,中空钢管混凝土(CFDST)柱具有很多优点,诸如自重轻和良好的循环性能。CFDST柱可能被用于桥梁,高层建筑,高架桥和输电塔结构中。内外钢管将承担来自上部结构和浇筑的湿混凝土的初始荷载。由这些初始荷载造成的钢管初应力和变形会影响CFDST构件的性能。因此,对外钢管单独承担初始荷载和内外钢管同时承担初始荷载时,CFDST柱的轴力性能进行讨论。建立通用的有限元模型预测钢管负荷时CFDST柱的性能。通过承担初始荷载和不承担初始荷载的CFDST柱的试验结果对该有限元模型进行验证。讨论初始荷载水平、长细比、空心率和材料强度对轴向强度的影响。最后,给出初始荷载下的CFDST柱的极限强度计算公式。     

贴钢法梁桥加固初探

合适的加固方案决定了对病害桥梁改造加固的经济和社会效益。因此,对桥梁的加固要因地制宜。梁桥的加固可分为提高结构强度和提高结构刚度,而这两种加固方法并不是独立的,对强度加固的同时可能也需要提高刚度,提高刚度的同时也可能需要强度,有些方案则需要两者同时得到加强。文章将分析桥梁上部结构贴钢法加固的原理和设计方法。     

钢垫板硬度对滑动铰节点性能的影响

滑动铰节点是用于抗弯钢架梁端的一种柔性连接。它是一种非对称的摩擦连接,能量通过梁下翼缘的开槽螺栓连接滑动耗散。摩阻力和荷载-位移滞回曲线的重复性依赖于所用垫片的类型。迄今为止,已对结构中使用的黄铜和低碳钢垫片进行了研究。对使用不同硬度钢垫板的滑移件进行相关试验,试验材料包括低碳钢、高强调质钢和耐磨钢。负担垫片滑动的梁和楔子的材料选用G-300低碳钢。模拟地震作用对试样进行动态测试。不同试样的所有位移曲线中,硬度最大的耐磨钢滑动特性最稳定、材料磨损最小、摩阻力最大。与黄铜相比,高强钢能够随时使用、成本较低、较易获得且不易腐蚀,这使得高强度钢成为更好的选择。     

Proposed design guidelines for strengthening of steel bridges with FRP materials

This paper focuses on the use of externally bonded high modulus carbon fiber reinforced polymer (HM CFRP) materials to strengthen steel bridges and structures. Proper installation of the CFRP materials is necessary to prevent premature failure due to debonding. The paper proposes guidelines and installation techniques based on the best practice reported in the literature and the extensive practical experience in bonding of composite materials. The surface preparation of the materials, the application of the adhesive and the detailing of the strengthening are provided in detail. The design guidelines include the structural design criteria for the use of high modulus CFRP materials as flexural strengthening system of typical steel–concrete composite bridge girders. The flexural design procedure is based on a moment–curvature analysis and a specified increase of the live load carried by the bridge to satisfy specific serviceability requirements. A bond model is also described which can be used to calculate the shear and peel stresses within the adhesive thickness. To prevent a premature debonding failure of the strengthening system, the criteria specify a maximum principle stress in the adhesive which cannot be exceeded for a given characteristic strength of an adhesive. A worked example is presented to illustrate the proposed flexural design approach. The research findings conclude that high modulus CFRP materials provide a promising alternative for strengthening steel bridges that can be easily designed and installed to increase their strength and stiffness.     

Characterisation of the behaviour of steel bridge bearings under cyclic load reversal

Seismic hazards pose a significant concern for older steel bridges in the Central and Eastern USA. The majority of these bridges still use steel bearings that are not designed to sustain earthquake loads. To assess older bridge vulnerability, an understanding of the cyclic behaviour of their components, such as steel bolster and rocker bearings, is needed. A theoretical analysis is conducted to understand steel bearing behaviour and their potential limit states, which also serves to validate bearing finite element models. The high fidelity models are used to evaluate the hysteretic behaviour of the bearings. The influence of gravity load on the response is evaluated to consider different bridge configurations, while varying the friction coefficient between steel surfaces allows for consideration of effects from ageing and corrosion. These parameters are shown to influence the response suggesting the need to consider ageing effects in assessing the vulnerability of in situ bridges.     

超高强度钢材钢结构的工程应用

为了探讨超高强度钢材在我国钢结构工程中应用的可行性,本文详细介绍了超高强度钢材的品种、力学性能和化学成分,分析了超高强度钢材钢结构构件的截面残余应力和几何初始缺陷及其对受压整体稳定特性的影响。结果表明,超高强度钢材轴心受压钢柱可采用比普通钢材钢柱高的整体稳定系数,提高其整体稳定承载力,更加充分地发挥超高强度钢材钢柱的强度优势。本文还介绍了超高强度钢材钢结构的优点及其在国内外多个建筑结构和桥梁工程中的具体应用情况和所取得的良好效果,为超高强度钢材钢结构在我国的工程应用提供了参考。     

钢管混凝土柱中的新型钢截面

在现代工程建设中,钢管混凝土（CFT）柱已逐渐成为高层建筑、桥梁等结构系统中的核心构件。在钢管混凝土的承载能力分析中有效参数有：钢与混凝土之间的粘结、钢管局部屈曲强度、混凝土徐变和连接处柱的负荷状态。考虑到这些有效参数,提议一种新截面,可用于高层建筑及大跨度桥梁。所提议钢截面的主要特点是内部纵向对称加劲肋。对此种截面（圆形和八角形）和钢管混凝土柱的常用截面进行轴向和循环荷载作用下的对比分析。同时采用有限元建模进行多种不同的分析。结果表明：新型截面在轴向和循环荷载下的强度和延性均有所增强,因此建议在施工中可采用此种截面。     

Extending the lifetime of steel truss bridges by cost-efficient strengthening interventions

Abstract

The large number of existing bridges and viaducts all around the country has become a major problem for bridge owners. In the specific case of steel truss bridges, a reasonable method to extend the lifetime of existing structures is represented by the introduction of new deck systems combined with diffused strengthening interventions. In this study, a stepwise approach considering different loading conditions is presented (historical and Eurocode loads). The structural analysis has been performed on a case study bridge with a finite element model (FEM) calibrated on load tests. It was found that the predicted deformation agreed reasonably with the experimental results. Different strengthening alternatives were analysed and discussed: the introduction of orthotropic deck; the construction of composite deck with differentiating thickness and ordinary concrete strength; the construction of composite deck with differentiating thickness and high concrete strength; in some cases, also steel-to-steel interventions on the bridge are provided. It has been found that the best structural strengthening alternative lies in the construction of a composite concrete or of an ultra high-performance concrete (UHPC) or an ultra high-performance fibre-reinforced concrete (UHPFRC) deck with a reduced thickness (compared with traditional interventions) resting on the existing steel structure combined with steel-to-steel interventions.     

浅析钢纤维混凝土施工技术在桥梁施工中的应用

公路桥梁等基础设施的建设力度逐渐加大,对于建筑材料方面的要求也逐渐升高。在这样的条件下,钢纤维混凝土凭借其自身的优势和便于施工的特点得到了广泛的应用。本文主要就钢纤维混凝土施工技术在桥梁施工中的应用进行了阐述和介绍。     

环氧涂层钢绞线拉索在斜拉桥中的应用

桥梁建设对索体防腐性能及强度要求不断提高 ,环氧涂层钢绞线因符合上述要求而被广泛应用 ,通过介绍宜宾中坝桥采用前支点挂篮及钢绞线斜拉索的施工过程 ,详述环氧涂层钢绞线拉索在斜拉桥中的具体应用。     

钢纤维混凝土桥面新技术

广深线某旧桥为三跨48m，宽17．sin的混凝土T梁桥，桥面铺装scm厚的中粒式沥青混凝土。为了适应国家经济建设和交通运输发展的需要，必须对旧桥右侧进行加宽，并且该桥位于曲线的缓和段内。本文主要对该桥桥面铺装课题进行应用研究。1桥面铺装方案该桥位于曲线的缓和段内，旧桥路拱横坡为双向2％，经加宽后渐变为单向0．2％。旧桥面采用scm厚的中粒式沥青混凝土，新桥面加宽部分计划采用钢筋混凝土铺装。但是，考虑到为了使桥面铺装层统一，满足材料使用要求和通车要求，又计划凿沥青混凝土铺装层后换用素水泥混凝土铺装。然而，由于该桥受…     

薄壁钢管混凝土梁-柱的钢板局部屈曲分析

高强钢和混凝土的应用,使得薄钢板开始应用在填充混凝土的钢管梁柱中。然而,在组合梁柱中薄钢板的应用可能会增加局部屈曲,这将减弱这些构件的强度和延性性能。通过有限元分析方法,分析了在填充混凝土的薄壁钢管梁-柱中钢板的临界局部屈曲和局部屈曲后性能。运用几何和材料非线性分析来研究在压力和平面内弯曲作用下钢板中的临界局部和后张局部屈曲强度。非线性分析中考虑了钢板的初始几何缺陷和残余应力,材料屈服和应变硬化。基于非线性有限元分析结果,本文提出一组设计公式,以确定这种组合梁柱的临界局部屈曲和钢板的极限强度。此外,还提出在不均匀压力作用下,钢板极限强度设计中有效宽度的计算公式。这一组设计公式可以直接用于组合梁-柱的设计和考虑局部屈曲作用后的薄壁钢管混凝土梁-柱分析。     

焊接连接的钢筋混凝土梁的静力性能

对高强混凝土组合梁桥梁中的钢和混凝土的连接件的静力和瞬时性能进行研究。在一系列条件下完成了拔出(Push-out)试验,并且依靠3D-F模型进行了分析。试验结果显示,平均最终剪切应力约为5·5MPa,而且结构响应主要依靠二维应力状态下的混凝土的行为。此外,粘合的连接件显示出很高的刚度和几乎与机械连接件一样的强度。对梁的模拟也表明,粘合的连接可以像梁一样被很精确地模拟。在混凝土桥面上开裂的风险也被显著减小,与那些采用机械连接相比的结构而言,这可能会增加粘合的钢-混凝土组合结构的耐久性。     

多孔钢梁在组合屈曲模态下的非线性分析

讨论了一般强度和高强度多孔钢梁在组合屈曲模态下的非线性分析。建立一个考虑腹板和翼缘初始几何缺陷、残余应力和材料非线性等情况的多孔钢梁的三维有限元模型。用具有不同长度,不同截面,不同荷载条件和不同失效模态的多孔梁的试验结果验证了此有限元模型。该模型能计算多孔梁的失效荷载,跨中荷载-挠度关系和失效模态。用120根多孔梁的有限元计算数据进行了参数分析,研究截面几何尺寸,梁长和钢材料强度对多孔梁强度和屈曲性能的影响。参数研究结果显示:由于组合腹板的扭转和腹板后屈曲引起的多孔梁失效对承载力有很大的影响。对于长细比较小的多孔梁,应用高强度钢材料将能显著提高失效荷载值。将有限元计算得到的失效荷载与利用澳洲规范计算的多孔梁平面外屈曲计算结果进行了对比,发现规范的计算结果对于平面外屈曲的一般强度多孔梁是不保守的,而对于组合腹板扭转和腹板后屈曲的高强度多孔梁的失效则非常保守。