港珠澳大桥正交异性钢桥面板疲劳特性研究

由结构体系和受力特性共同决定,疲劳问题是正交异性钢桥面板应用和发展所面临的重要课题。以典型的正交异性桥面板钢箱梁桥——港珠澳大桥为研究对象,通过足尺试件模型对5类重要的正交异性钢桥面板疲劳易损部位进行试验和理论研究。选取最易发生疲劳损伤的梁段作为模型设计的依据,针对各关键疲劳易损部位设计4组共8个足尺疲劳试件模型;对设计寿命期内各疲劳易损部位的疲劳特性进行试验验证,在此基础上选取典型疲劳易损部位进行疲劳损伤及疲劳性能试验,建立基于理论模型和弹塑性断裂力学的疲劳损伤裂纹扩展模拟方法。研究结果表明:港珠澳大桥正交异性钢桥面板的疲劳性能满足设计要求;正交异性钢桥面板疲劳易损部位的疲劳性能存在较大差异;疲劳裂纹附近区域的应力分布随裂纹的扩展而不断发生改变,可据此判别裂纹的萌生并监测其扩展;所提出的方法适用于待研究疲劳易损部位的疲劳寿命评估。     

正交异性钢桥面板设计应用研究

总结了正交异性钢桥面板的发展概况及结构形式,分析了不同截面形式在不同结构体系中的适用性,对正交异性钢桥面板的应力计算和疲劳裂缝成因进行了细致的分析,并总结了目前常用的钢桥面板应力计算方法和疲劳计算方法,以供借鉴。     

正交异性钢桥面板纵肋与桥面板连接细节的疲劳评估及修复措施

正交异性钢桥面板由于具有自重轻、极限承载力大等优点目前广泛应用于大、中跨径桥梁中,我国已建和在建的大跨径桥梁也大多采用正交异性钢桥面板.但由于正交异性钢桥面板结构构造复杂,受焊接残余应力影响大,钢桥面板直接位于车轮荷载的作用下,一些构造细节处极易发生疲劳开裂.以国内某大桥正交异性钢桥面板为例,针对纵肋与桥面板之间的疲劳...     

大节段正交异性钢桥面板模型疲劳试验研究

正交异性钢桥面板因构造与受力复杂特殊、加工工艺繁琐、焊缝数量众多,且关于其疲劳性能的试验研究还相对不够充分,以致不能完全适应当代钢桥发展与建造的需求。本文以某大跨度悬索桥的正交异性钢桥面板为工程背景,开展1:2缩尺的大节段模型疲劳试验,研究正交异性钢桥面板其关键细节的疲劳性能,以期望丰富我国正交异性钢桥面板疲劳试验的数据库。结果发现:对称测点其所测试数据与加载关系曲线出现对称特征;静态加载试验过程中,测点加载与卸载曲线比较对称且有良好的可恢复性;6#苹果形开孔右上侧出现疲劳裂纹,疲劳循环次数达到200万次时其长度约为7.5mm,260万次时扩展至31mm左右,裂纹扩展率随荷载增加而增大,而其余部位未发现疲劳裂纹的产生。     

基于热点应力法的正交异性钢桥面板疲劳分析及验算

为了更加准确地评估钢桥面板的疲劳性能,提出基于热点应力法的钢桥面板疲劳分析及验算方法.该方法针对所分析的正交异性钢桥面板,首先利用有限元软件建立桥面系模型,然后采用热点应力法得到验算部位的应力历程,最后根据泄水法计算相应的热点应力幅并进行疲劳验算.以某三塔四跨双层钢桁梁悬索桥为例,针对该桥采用的正交异性钢桥面板,利用本...     

正交异性桥面板结构疲劳和应力集中研究综述

<正>交异性钢桥面板具有自重轻,承载能力大,施工周期短等优点,在国内外的大、中跨径桥梁中得到广泛应用。由于车辆的反复荷载,桥面板疲劳裂缝和应力集中问题严重突出。本文结合有关正交异性钢桥面板疲劳的一些研究,阐述了正交异性钢桥面板细节构造的疲劳问题和相关结论,简述了钢桥面板的疲劳评估方法,并对正交异性钢桥面板的疲劳研究进行总结。     

对正交异性钢桥面板构造抗疲劳设计方法的分析

国内近年来正交异性整体钢桥面体系不仅在公路钢桥,而且在铁路钢桥上得到大量的应用。首先介绍国内对正交异性钢桥面板应用的总体情况,包括还在建造和设计中的一些新桥。对正交异性钢桥面板疲劳构造细节进行分析,重点分析疲劳裂纹易发生部位和形成的原因。根据分析结果,设计出经简化且能包络实际受力最不利状态的试件进行疲劳试验。所涉及的构造细节包括桥梁实际工艺下的U肋与桥面板焊缝、U肋与横隔板之间有过焊孔和没有过焊孔时横隔板与桥面板焊缝、U肋嵌补段焊缝、U肋与横隔板之间挖孔焊缝,共计有6个构造细节。提出采用准热点应力统计方法确定正交异性钢桥面板构造细节名义应力的观点,对制定抗疲劳设计方法的研究技术路线作出归纳,进而提出正交异性钢桥面板疲劳设计方法的建议。     

横隔板缺口形式对正交异性钢桥面板疲劳性能的影响研究

以梯形及矩形截面形状的纵向加劲肋组合3种缺口类型的横隔板,建立正交异性闭口加劲钢桥面板有限元实体模型进行加载,用ANSYS程序计算分析了横隔板不同缺口形式的正交异性钢桥面板力学性能、正交异性钢桥面板、纵肋、横隔板三者连接处的应力状态以及不同缺口形式的正交异性钢桥面板疲劳性能,研究了横隔板缺口形式对正交异性钢桥面板静力力学性能以及疲劳性能的影响。     

正交异性钢桥面板结构体系的疲劳破坏模式和抗力评估

正交异性钢桥面板的疲劳问题属于包含多疲劳破坏模式的结构体系疲劳问题。基于这一本质特性,以典型的正交异性钢桥面板结构体系为研究对象,由结构体系的主导疲劳破坏模式出发,提出正交异性钢桥面板结构体系疲劳抗力评估的新方法。以纵肋与顶板焊接细节和纵肋与横隔板交叉构造细节为主要研究对象,设计8个足尺节段模型,主要包括传统纵肋与顶板焊接细节、新型镦边纵肋与顶板焊接细节和纵肋与横隔板交叉构造细节,通过模型试验研究了两类重要构造细节的主导疲劳破坏模式和实际疲劳抗力,在此基础上结合切口应力评估方法探讨正交异性钢桥面板构造细节切口应力S-N曲线方程、结构体系的主导疲劳破坏模式等关键问题。研究结果表明：传统纵肋与顶板焊接细节和新型镦边纵肋与顶板焊接细节的主导疲劳破坏模式均为疲劳裂纹萌生于焊根并沿顶板厚度方向扩展,二者的实际疲劳抗力基本相同;纵肋与横隔板交叉构造细节的疲劳破坏模式为焊趾开裂沿纵肋腹板方向扩展;对于研究对象而言,萌生于纵肋与顶板焊接细节焊根并沿顶板厚度方向扩展的疲劳破坏模式为控制结构体系疲劳抗力的主导疲劳破坏模式。     

钢桥面系足尺结构疲劳试验研究现状

正交异性板及铺装结构体系疲劳问题一直是难题,通过综合对比分析国内外正交异性板足尺结构研究现状,总结钢桥面系足尺疲劳试验能够有效、准确、快速反映结构真实力学特征,验证疲劳损伤发展规律和长期耐久性,可为我国长大桥梁正交异形钢桥面板及铺装结构体系疲劳研究和设计提供了科学依据和理论参考。     

正交异性钢桥面铺装层疲劳寿命的断裂力学分析

计算和分析正交异性钢桥面铺装层表面裂缝应力强度因子,在此基础上应用Paris扩展公式预测铺装层疲劳寿命。将奇异单元布置在铺装层表面裂缝前沿,建立正交异性钢桥面系三维断裂力学有限元模型,计算铺装层表面裂缝的应力强度因子;分析裂缝应力强度因子随轴载作用位置的变化规律,确定了带裂缝铺装层轴载作用的最不利荷位;以最不利荷位作为轴载作用的标准荷位,计算应力强度因子随裂缝扩展深度的变化,并数值拟合得到了应力强度因子与裂缝深度的关系式;将应力强度因子的深度关系式代入Paris公式,积分得到铺装层的疲劳寿命。计算结果表明,基于钢桥面铺装层带裂缝工作的事实,应用断裂力学方法预测钢桥面铺装层疲劳寿命是可行的。     

轻型组合桥面板球扁钢纵肋-横隔板连接细节局部应力分析

为降低正交异性钢桥面板疲劳开裂的风险,提出带球扁钢纵肋的轻型组合桥面板方案。以洞庭湖二桥轻型组合桥面板为工程背景,建立钢桁梁局部有限元模型和球扁纵肋-横隔板连接细节的子模型,并基于热点应力法,对横隔板上开孔孔型和厚度进行了参数分析。研究表明：球扁纵肋-横隔板连接处3个典型疲劳细节的疲劳性能受横隔板厚度影响显著|综合比较,苹果型开孔的疲劳性能最优。为进一步验证轻型组合桥面板的球扁钢纵肋-横隔板连接处3个细节的疲劳性能,开展了足尺模型疲劳试验,试验模型采用16mm厚带苹果型开孔的横隔板设计。疲劳试验中,控制细节（横隔板切口自由边缘）的应力幅为90.6MPa,历经250万次循环加载后,试验模型中典型疲劳细节均未出现疲劳裂纹。这表明,带球扁钢纵肋的轻型组合桥面板关键细节的疲劳性能良好,能满足洞庭湖二桥的工程要求。     

正交异性钢桥面板疲劳裂纹的维修加固方法

正交异性钢桥面板的疲劳裂纹是既有钢桥的常见病害,其维修加固难于新桥建设,必须遵守耐久性等基本原则。钢桥面板的维修加固方法分为三类:第一类是改进铺装层结构,减小整个钢桥面板所有部位的应力;第二类是局部补强或者改进纵向加劲肋的构造;第三类是直接对发生疲劳裂纹的局部进行维修。如果疲劳裂纹比较严重,如纵向加劲肋与横肋之间的连接失效、或者纵向加劲肋与面板的连接焊缝处裂纹向上贯穿面板等,则需要同时采用第一类和第三类加固方法。     

细长正交异性钢桥面板的疲劳寿命评估

在多种焊接节点中产生的疲劳裂缝,也产生在大量细长正交异性钢桥面板中。一部分裂缝在桥梁投入使用短短几年之后便会出现,所以对于桥面焊接节点的疲劳寿命评估较复杂。这同时也是局部压应力会随着很多因素而随机变化的原因,尤其是那些在车胎、公路和钢结构的动力交互作用面上。     

Instandsetzung und Verstärkung von Stahlbrücken mit Kategorie‐3‐Schäden

Reinforcing steel bridges with category 3 damages – report on a BASt research project. In recent years, fatigue damages have been observed at the main supporting structure of steel bridges, the orthotropic decks, as well as the transverse structure of steel bridges (the so‐called category 3‐failure). The rapidly increasing road traffic intensifies the situation resulting in a huge amount of steel bridges affected by fatigue damages. Existing steel bridges with category 3‐fatigue cracks have been intensively investigated. Fatigue failure modes and general evaluation criteria have been summarized, analysed and categorized, in order to enable first fundamental and time‐efficient definition and classification of category 3‐damages. FE‐simulations of transversal steel bridge structures (with and without reinforcements) have been carried out to evaluate and review the structural bridge concepts. Based on these studies, a special way of the steel bridges' maintenance has been followed up, which is removing all possible transversal bracings. Finally, different options of maintenance and repair have been investigated both newly and successfully applied in the recent past. Appropriate actions for solving essential category 3‐fatigue problems are presented.     

Experimental study and numerical analysis on mechanical behavior of T-shape stiffened orthotropic steel-concrete composite bridge decks

A new-type of orthotropic steel-concrete composite bridge deck system was developed, by casting the concrete overlay on the top of the orthotropic steel deck ribbed with T-shape steel members. To study its mechanical behavior (in terms of failure mode, load-deflection relationship, concrete crack initiation and propagation, strength, stiffness and so on), two new-type orthotropic steel-concrete composite bridge decks with different section dimensions were experimentally investigated and two reference decks (reinforced concrete deck and orthotropic steel deck) were also involved in the research for comparison. For the two new-type orthotropic steel-concrete composite decks, the average value of ultimate loads per width is 885.7kN, which is 2.35 and 1.61 times of that of the concrete and steel reference decks with almost the same section height. Experimental results proved that the composite deck can effectively control the crack initiation and propagation in the concrete and postpone the yielding of the steel bars and steel plates, due to the composite action between the concrete overlay and the underlying steel plate. Furthermore, the Finite Element (FE) model of the orthotropic steel-concrete composite deck was developed and validated by test results. A parametric study is conducted regarding to the stiffness of shear studs. With the validated FE model, stress distribution in the underlying steel plate and T-shape stiffeners and development of concrete cracking in the concrete overlay were characterized at different load levels.     

Orthotrope Fahrbahnplatte – Entwicklungen und Möglichkeiten für die Zukunft

Orthotropic decks – developments and future outlook. Bridges with steel orthotropic decks, first introduced in the 1950s in Germany, have been subsequently built in other countries, with several thousand of such structures now in service throughout the world. The performance record of orthotropic decks has been satisfactory, excepting occasional fatigue cracking which had occurred on some decks built in the 1960s and 1970s, mainly caused by inappropriate details and fabrication defects. Specific causes of such failures are discussed. Developments of design methods for orthotropic decks are discussed. For basic design simplified approaches, such as the Pelikan‐Esslinger method, are generally used. The applicability of the classical (Wöhler's) fatigue theory is limited. Therefor current design specifications permit empirical fatigue safety assessment by conformance with approved geometric standards. Due to their light weight, durability and load carrying capacity, orthotropic decks have a promising future being indispensable in the super‐long span bridges. Because of their capability for being structurally integrated with the main members of the existing steel bridges, orthotropic decks are also excellently suited for replacing the deteriorating concrete decks. In the U.S. nearly 40% of highway bridges are now considered “structurally deficient” or “functionally obsolete”, with failed concrete decks accounting for about two‐thirds of the deficiency cases. Several major U.S. bridges have recently received new orthotropic decks. Special problems encountered with redecking are discussed.     

Performance of steel bridge deck pavement structure with ultra high performance concrete based on resin bonding

This research investigated a pavement system on steel bridge decks that use epoxy resin (EP) bonded ultra-high performance concrete (UHPC). Through FEM analysis and static and dynamic bending fatigue tests of the composite structure, the influences of the interface of the pavement layer, reinforcement, and different paving materials on the structural performance were compared and analyzed. The results show that the resin bonded UHPC pavement structure can reduce the weld strain in the steel plate by about 32% and the relative deflection between ribs by about 52% under standard axial load conditions compared to traditional pavements. The EP bonding layer can nearly double the drawing strength of the pavement interface from 1.3 MPa, and improve the bending resistance of the UHPC structure on steel bridge decks by about 50%; the bending resistance of reinforced UHPC structures is twice that of unreinforced UHPC structure, and the dynamic deflection of the UHPC pavement structure increases exponentially with increasing fatigue load. The fatigue life is about 1.2 × 10⁷ cycles under a fixed force of 9 kN and a dynamic deflection of 0.35 mm, which meets the requirements for fatigue performance of pavements on steel bridge decks under traffic conditions of large flow and heavy load.