箱肋拱桥施工技术

结合工程实例,介绍了箱肋拱桥施工技术,从箱肋拱桥的特点、拱肋的施工、拱肋的吊装等方面进行了论述,指出箱肋拱桥的施工技术,具有结构简单、自重轻、跨度大、造价低、施工方便、工期短、质量保证、外型美观等特点,值得推广应用。     

大跨度V形拱钢拱桥稳定性分析

V形拱桥造型美观,结构体系新颖,随着其跨度增大,拱肋建筑高度增高,稳定问题突出,对其稳定性进行分析具有重要意义。以现有理论为基础,主跨115 m的V形拱桥为背景,采用Midas civil有限元软件建立模型,对该桥成桥状态的结构稳定性进行了分析。结果表明,该桥的整体失稳主要表现为拱肋面外失稳;拉索位于拱肋上的着力点和横撑加装位置宜设置在拱顶靠近两拱肋相交侧。     

人行景观桥钢箱梁吊装施工技术

以宜昌市职教园人行景观桥工程为例,针对其钢箱梁体型不规则、重量较大的特点,从箱梁分节、组织运输、吊装作业等多角度完善施工方案,有效克服了现场作业环境、施工机具性能等限制因素,并结合现场吊装经验提出建议,为类似工程建设提供了借鉴。     

Static analysis of cable-stayed bridge with CFT arch ribs

A new type of cable supported bridge, cable-stayed CFT arch bridge, was proposed and its static strength was studied in this paper. Arch ribs consist of concrete filled steel tubes (CFT). CFTs have high resistance against bending moments and compressive axial forces and are ideal as arch ribs. A cable-stayed CFT arch bridge with a main-span of 300 m was designed and the safety of its structural members was checked by the limit state design method. Large deformation analysis was used to obtain sectional forces. The CFT arch ribs and the steel box girders and towers of the designed bridge satisfied the required safety criteria for ultimate design loads. The applied loads were further increased until the bridge collapsed when the arch ribs buckled. The amount of steel required for the cable-stayed CFT arch bridge was significantly lower than that for the cable-stayed bridge. It has been found that the proposed cable-stayed CFT arch bridge is feasible and potentially economical.     

谈拱承式预应力钢箱梁天桥施工方法

分析了拱承式预应力钢箱梁天桥的特点,根据该桥梁的施工原理,从图纸设计、胎架制作、预拼装、构件吊装等方面,阐述了其施工工艺流程及操作要点,为同类型桥梁施工积累了经验。     

中承式劲性骨架钢筋混凝土箱肋拱桥施工技术

通过对安康高速公路堰吉河大桥中承式劲性骨架钢管混凝土箱肋拱桥施工过程的研究,总结出了该类桥梁的施工工艺与方法,并从拱座基础施工、裸拱施工、灌注钢管混凝土、横梁安装等方面作了论述,可为同类桥梁施工提供借鉴。     

预应力混凝土连续箱梁桥裂缝控制

根据预应力混凝土连续箱梁普遍开裂的工程实际，结合有限元分析结果，对计算方法、混凝土控制应力、温度梯度模式、腹板预应力束布置等抗裂因素提出了设计建议。从跨径比例、箱梁断面尺寸、非预应力钢筋的设置等几方面介绍了防裂构造措施。     

曲线箱梁桥空间预应力效应分析

曲线箱形梁桥是空间复杂受力的结构体系,预应力效应一方面能提高构件的承载能力,另一方面也可能对结构带来一些不利的影响。采用三维实体单元和杆单元相结合的空间组合有限元方法,对一座两跨曲线预应力混凝土箱形连续梁桥进行空间受力分析。针对曲线箱形梁的力学特点,对空间曲线钢束摩阻损失的计算方法进行分析。采用组合有限元法和简化方法分析预应力径向力对箱梁腹板的作用效应,比较两者的计算结果差异。采用两种计算模型,分析了预应力对支座受力的影响,对径向支座间距设置和改善支座受力的方法进行了研究。根据预应力效应的分析结果,得到了一些有益的结论,为进一步完善曲线预应力混凝土箱梁桥的设计提供了依据。     

现浇箱梁桥横向裂缝成因计算分析

某现浇箱梁桥在未通车情况下出现了横向裂缝,通过对裂缝开裂断面进行详细的结构复算,通过承载能力复算、正常使用极限状态裂缝宽度及开裂弯矩对比计算对裂缝成因进行了分析定性,最后对病害提出了相应的处理意见。     

Nonlinear analysis of multi-cell reinforced concrete box girder bridges

A numerical method of analysis is developed to determine the nonlinear response, collapse mechanisms and ultimate failure loads of multi-cell RC (reinforced concrete) box girder bridges under stepwise increasing static loads. Nonlinearities considered are material nonlinearities inherent in RC members such as cracking of the concrete, yielding of the reinforcement and formation of plastic hinges due to shear and flexure. The analytical model, based on a three-dimensional grillage, is developed for multicellular structures of arbitrary plan geometry and constant height. Realistic but simple assumptions for the interaction of internal forces due to flexure, shear and torsion in the cellular structure, as well as idealized trilinear force-deformation characteristics for the individual members comprising the grillage, result in a very economical nonlinear analytical model. The proposed analytical scheme, which is based on a mixed model formulation at the element level, is demonstrated and tested on a series of numerical examples and the analytical results indicate good agreement with experimental results obtained from large scale model tests on RC box girder bridges.     

桁架拱桥与钢架拱桥的安装技术

根据桥梁施工经验，介绍了桁架拱桥和钢架拱桥的安装要点及多种安装方案，并对各方案总结了安装的方法和技巧，指出二者将在公路桥梁施工中被广泛应用。     

Time-variant reliability profiles for steel girder bridges

Evaluation of existing steel bridges becomes more important due to natural aging, increasing load spectra, deterioration caused by corrosion, and other problems. In the result, bridge structures exposed to aggressive environmental conditions are subjected to time-variant changes of resistance. Therefore, there is a need for evaluation procedures for an accurate prediction of the load carrying capacity and reliability of bridge structures, in order to make rational decisions about repair, rehabilitation, and expected life-cycle costs. The objective of this paper is to develop time-variant reliability models for steel girder bridges. Traditional methods based on deterministic analysis do not reveal the actual load carrying capacity of the structure. The proposed approach is based on reliability analysis of components and structural systems. The study involves the selection of representative structures, formulation of limit state functions, development of load models, development of resistance models for corroded steel girders, development of the reliability analysis method, reliability analysis of selected bridges, and development of the time-dependant reliability profiles including deterioration due to corrosion. The results of the study can be used for a better prediction of the service life of deteriorating steel girder bridges, and development of optimal reliability-based maintenance strategies.     

谈小半径弯箱梁桥设计

针对小半径曲线梁桥较同等跨径的直线梁桥的受力要复杂的特点,采用MIDAS软件建立了梁格模型,通过分析比较在恒载和活载的作用下,小半径弯箱梁桥采用不同的支座布置形式时,内侧和外侧腹板的受力情况,从而得出一些有益的结论。     

双箱单室钢箱梁桥设计

钢桥是大跨度桥梁的主要形式。以山东XX双箱单室钢桥为例,详细介绍钢桥总体优化设计,通过桥梁博士建立有限元模型,计算结果表明拉/压弯构件弯曲正应力验算、剪应力验算、折算应力验算、挠度验算、疲劳验算均满足要求。     

钢箱梁的施工工艺

指出钢箱梁由于其优异的性能被用于建筑结构中,其关键的施工工艺主要有钢箱梁制造工艺、内部构件的焊接以及螺栓的采用,针对这三个主要方面进行了较为详细的探讨,以期对该类型工程项目施工起到参考借鉴作用。     

大跨径预应力混凝土箱梁桥设计中的几个问题

预应力混凝土箱梁桥以其良好的结构性能和简洁优美的外形,在世界各地得到了广泛应用。但近年来,一些大跨径预应力混凝土箱梁桥在运营一段时间后,普遍出现箱梁腹板开裂和跨中下挠等病害,这些病害影响了桥梁结构的使用性能和耐久性,而导致这些病害的原因还没有完全明确。针对这些病害,从箱梁纵向预应力设计、竖向预应力设计、竖向预应力损失、结构构造设计、箍筋配置、混凝土材料特性等方面对箱梁进行了研究分析,得出了一些具有实用价值的结论。重点比较了两种纵向预应力配束方案,结果表明,设置下弯束是抵抗腹板主拉应力过大的有效方式。对导致箱梁结构长期下挠的主要成因在机理上进行了解释,剪切变形与斜裂缝发展对薄壁箱梁的长期变形影响不可忽视,并对开展控制跨中长期下挠等方面的研究提出了建议。     

预应力混凝土连续箱梁桥的养护与加固

针对不同部位、不同类型的裂缝,提出了预应力混凝土连续箱梁桥的各种相应加固措施及施工工艺要求,并将其中的几种措施应用到一座开裂的大跨径预应力混凝土连续箱梁桥的加固工程中,该桥加固后的荷载试验及两年的运营情况表明了加固方案的合理性.     

装配式预应力混凝土箱梁桥施工方案

简要介绍了钻孔灌注桩、承台、墩柱及盖梁的施工要点,并对装配式预应力混凝土连续箱梁的预制和安装施工方案进行了论述,提出了施工注意事项,为今后类似工程施工提供了参考借鉴。     

预应力混凝土连续箱梁桥防裂设计建议

针对预应力混凝土连续箱梁桥普遍开裂的情况，根据不同类型、不同部位的裂缝，从预应力束的设置、箱梁翼板有效宽度和内力增大系数、箱梁构造要求、温度梯度模式、普通钢筋配置等方面提出了一些预应力混凝土连续箱梁防裂设计建议，以供同行商榷。     

采用支撑杆件提高钢箱梁正交异性板疲劳性能研究

交通运输的迅速发展使得钢箱梁正交异性板的疲劳问题日趋突出。为研究设置支撑杆件对钢箱梁正交异性板疲劳性能的影响,制作试件进行室内试验,并采用有限元软件ABAQUS建立有限元模型,分析在无支撑杆件和有支撑杆件的情况下,钢箱梁正交异性板易疲劳开裂位置应力幅（最大荷载时的应力与无荷载时应力之差）的变化。试验和有限元对比结果表明：试验结果和有限元模拟结果吻合良好,支撑杆件的设置可将钢箱梁正交异性板U肋及T肋开槽处的应力幅减小约40%~60%,其中个别位置应力幅减小占比（无、有支撑时的应力幅差值与无支撑时应力幅之比）可达70%;支撑杆件的设置可将顶板跨中位置应力幅减小约20%~40%,其中个别位置应力幅减小占比可达50%。有限元参数分析结果表明：离支撑杆位置越近,开槽位置处的应力幅减小占比越大;随着支撑杆件直径的增大,应力幅减小占比增大,但增大幅度逐渐减小。合理使用支撑杆件能有效减小钢箱梁正交异性板易疲劳开裂部位的应力幅,可在较低的成本下减少钢箱梁正交异性板疲劳破坏的发生,提高其疲劳寿命。