浅谈桥梁的加固施工

根据公路旧桥加固方面的实践经验，按桥梁的组成介绍了旧桥上部及下部结构的加固技术措施，并总结了桥梁的常见加固方法，通过加固方法的实施，从而达到提高桥梁承载能力的目的。     

钢筋锈蚀对旧桥极限承载能力的影响

通过对某旧桥的实际情况进行数据采集，分别进行了实测承载力计算和理论承载力计算，分析钢筋锈蚀对旧桥的极限承载能力的影响，同时将实测值和理论值进行了对比，从而为旧桥加固提供了依据。     

公路旧桥加固技术探讨

结合近年来对超限运输桥梁及大中型桥梁的加固实践,分别对旧桥上部结构、下部结构、旧桥基础、桥面铺装等部位的加固处理方法进行了介绍,以提高旧桥的承载能力,确保公路旧桥的交通运输安全。     

旧桥扩宽加固的关键技术研究

随着交通运输量和桥上荷载的大幅增加,很多年代久远的旧桥承载能力不够,使得安全事故的隐患越来越多。所以,旧桥加固是加强交通安全的重要保障。在一些旧桥主体结构没有损伤的情况下,对一些可以修复的部位进行强化处理,既能节省拆除旧桥时造成的资金浪费,又能节省施工所需的时间,保障交通即时恢复。旧桥加固的方法使旧桥的承载能力增加,并且使行车条件有所改善,增加了旧桥的使用寿命。对旧桥加固进行大量研究后,根据桥梁病害形成的原因,结合旧桥的损伤部位总结了常见的旧桥加固方法,制定了加固施工方案,并列举实例进行对比分析。旧桥加固后的结果显示,其满足承载力和当前交通运输的要求,对类似工程施工具有参考价值。     

城市旧桥承载能力的模糊性与随机性的综合评价

本文从理论上分析和研究了影响城市旧桥承载能力的各种因素的模糊性和随机性。依据极限状态法原理，运用模糊评判与随机分析的综合方法，确定出旧桥承载能力的指标现状及安全度的范围。通过广州市增步大桥的旧桥鉴定与加固实例，进行了具体分析与计算。对城市旧桥的评价与利用具有一定的参考价值。     

预应力加固技术在桥梁维修加固中的应用

目前国内外普遍出现旧桥老化现象,给桥梁的正常使用和安全运营带来严重影响。现阶段,旧桥加固维修已渐渐成为了一项热门的新技术。而旧梁的维修加固技术施工中,预应力加固技术被广泛应用于实际工程中,也取得了许多成功经验。预应力加固技术相比被动式加固技术而言,最大优势是可以在不改变旧桥结构形式体系的情况下恢复或者显著增强旧桥的承载能力,达到加固桥梁的目的,并且该加固技术有着极高的实用优势。     

危旧桥梁养护与维修加固初探

本文讲述了目前对天水公路总段危旧桥加固的一些先进方法的探索。为提高旧桥的承载能力,确保交通运输的安全,从粘贴钢板法加固、碳纤维布加固、桥面铺装层加固等方面对公路旧桥采取的一些加固措施。     

旧公路桥的加固与改造措施

旧桥加固可提高旧桥的承载能力,确保交通运输的畅通安全.桥梁的加固方法主要有:塞缝灌浆,上部构造改建,旧桥下部结构加固,旧桥基础加固,桥面铺装层的加固.同时,要加强公路旧桥的管理,使其处于正常的工作状态.     

清远北江大桥承载能力鉴定及加固方案建议

介绍了刚架拱旧桥的承载能力鉴定方法,对加固方案进行了探讨。     

桥梁加固与维修的基本措施

(1)旧桥上部构件进行加固与维修对旧桥上部构造进行维修的方法有 :压力灌浆法、喷射灌浆法及填缝法。主要采用高标号的水泥砂浆或环氧树脂砂浆等。对旧桥上部构造进行加固的方法主要有 :桥面补强层加固法、梁下部截面增强法、钢板粘结法、改变结构体系加固法、预应力加固法、更换部分或全部主梁法。前面 3种方法主要是改变行车道板的形心位置 ,增大梁的抗弯断面 ,这几种方法虽然增大了桥梁上部构造的承载能力 ,但由于其增加恒载较大 ,提高承载能力不明显。第 4、5种加固方法改变了原有结构的受力状况 ,加固效果较显著。最后 1种方法造价较高…     

混凝土斜拉桥与T构协作体系的极限承载力研究

考虑结构的材料非线性和几何非线性,通过对协作体系金马大桥进行全过程非线性分析,得到了结构的极限承载力。研究了混凝土收缩徐变、加劲梁配筋率、斜拉索的安全系数、加载方式等因素对协作体系桥梁的极限承载力的影响,结果表明斜拉索的设计安全系数是很重要的影响因素,应加以重视;全桥和半桥加载时,弹塑性极限活荷载安全系数分别为21.4和9.67,表明金马大桥这种协作体系具有良好的极限承载能力;其弹塑性极限承载力远小于弹性极限承载力,研究结果可以为同类桥梁工程的设计和计算提供参考。     

既有桥梁承载能力评估的研究现状和展望

本文对既有桥梁承载能力评估方法和研究现状进行了论述,提出了桥梁承载能力评估中存在的问题,对其研究和发展的方向进行了探索.     

Failure tests on concrete bridges: Have we learnt the lessons?

Full-scale failure tests of bridges are important for improving understanding of bridges’ behaviour and refining assessment methods. However, such experiments are challenging, often expensive, and thus rare. This paper provides a review of failure tests on concrete bridges, focusing on lessons from them. In total, 40 tests to failure of 30 bridges have been identified. These include various types of bridges, with reinforced concrete or prestressed concrete superstructures, composed of slabs, girders and combinations thereof. Generally, the tests indicated that theoretical calculations of the load-carrying capacity based on methods traditionally used for design and assessment provide conservative estimates. It can also be concluded that almost a third of the experiments resulted in unexpected types of failures, mainly shear instead of flexure. In addition, differences between theoretical and tested capacities are often apparently due to inaccurate representation of geometry, boundary conditions and materials.     

屈服强度550MPa高强冷弯薄壁型钢轴压构件承载力设计

高强冷弯薄壁型钢结构在国外低层住宅和门式刚架体系中应用较广,国内已开始采用,但尚无相应设计规范可依。针对屈服强度550MPa高强钢材冷弯薄壁型钢结构常用的轴压构件的承载力设计方法进行了研究,包括其承载力计算模式及设计可靠度分析,并据此提出了相应的设计方法。最后,通过国内外现有相关试验数据的分析,验证了所提出的强度设计指标及承载力设计方法的合理性与可靠性。     

A multi-level strategy for successively improved structural analysis of existing concrete bridges: examination using a prestressed concrete bridge tested to failure

This paper describes a multi-level strategy with increased complexity through four levels of structural analysis of concrete bridges. The concept was developed to provide a procedure that supports enhanced assessments with better understanding of the structure and more precise predictions of the load-carrying capacity. In order to demonstrate and examine the multi-level strategy, a continuous multi-span prestressed concrete girder bridge, tested until shear failure, was investigated. Calculations of the load-carrying capacity at the initial level of the multi-level strategy consistently resulted in underestimated capacities, with the predicted load ranging from 25% to 78% of the tested failure load, depending on the local resistance model applied. The initial assessment was also associated with issues of localising the shear failure accurately and, consequently, refined structural analysis at an enhanced level was recommended. Enhanced assessment using nonlinear finite element (FE) analysis precisely reproduced the behaviour observed in the experimental test, capturing the actual failure mechanism and the load-carrying capacity with less than 4% deviation to the test. Thus, the enhanced level of assessment, using the proposed multi-level strategy, can be considered to be accurate, but the study also shows the importance of using guidelines for nonlinear FE analysis and bridge-specific information.     

预制空心板简支梁桥健康检测及加固技术研究

在桥梁设计、施工和使用中,桥梁的健康检测、加固及维护对于改善桥梁承载和质量具有重要意义。文中以实际已建桥梁为例,对桥梁的检测内容和方法进行了讨论,分析了桥梁存在的病害及产生的原因,提出了行之有效的加固方法,裨益对类似的混凝土结构桥梁的检测加固提供参考。     

既有公路桥梁评估方法研究现状

由于使用、超载、环境作用以及功能退化等人为或自然因素,导致公路桥梁在服役期间发生各种结构损伤,如何对其进行评估已成为世界各国桥梁工程界研究的热点问题之一.本文在已有研究成果的基础上,从规范评估方法、承载力可靠度和疲劳可靠度、系统可靠度以及整体结构评估等方面,对既有公路桥梁评估的研究现状进行了总结与阐述,并指出了既有公路桥梁评估领域存在的问题以及研究方向.     

GFRP套管钢筋混凝土短柱轴压力学性能试验研究

为研究GFRP套管钢筋混凝土短柱的轴压力学性能,进行了22个GFRP套管钢筋混凝土短柱和6个无GFRP套管约束的钢筋混凝土短柱对比试验。研究了影响GFRP套管钢筋混凝土组合短柱轴压力学性能的主要因素,包括GFRP套管不同的受力方式、混凝土强度、纵筋配筋率等。试验结果表明:由于GFRP套管的约束,提高了核心混凝土的强度,增大了核心混凝土的变形能力;GFRP套管在不同的受力方式下,组合短柱的轴压承载力和变形基本相同;GFRP套管内配置纵筋可提高GFRP套管混凝土短柱的轴压承载力,适当提高纵筋配筋率可改善短柱的延性。根据试验结果及现有FRP管约束混凝土轴心抗压强度计算公式,建议了GFRP套管钢筋混凝土短柱承载力计算公式,计算结果与试验结果基本吻合。     

PVC-CFRP管钢筋混凝土轴压短柱试验研究

通过10根PVC-CFRP管钢筋混凝土短柱轴压试验,分析CFRP条带环箍间距和轴向配筋等因素对PVC-CFRP管钢筋混凝土短柱承载力、变形以及破坏形态的影响。试验研究表明：与无筋试件相比,配筋率为1.8%的配筋试件的承载力和轴向极限压应变分别提高约24%和16%;随着CFRP条带环箍间距的增大,配筋试件的承载力和轴向极限压应变逐渐减小;配筋试件破坏时,试件中部多条CFRP条带拉断并伴随纵向钢筋压屈。PVC-CFRP管钢筋混凝土的应力-应变关系曲线可以分为三段：第一段的应力-应变关系曲线为抛物线;第二段为曲线过渡段;第三段为强化段,配筋试件的应力和应变一直处于递增状态,与无筋试件相比,配筋试件强化段斜率较大。根据静力平衡条件和极限平衡条件,推导出PVC-FRP管混凝土柱承载力的计算式,计算结果与试验值吻合较好。     

Assessment of the load-carrying capacity of multi-span masonry arch bridges using fibre beam elements

An approach that makes use of non-linear beam elements with fibre cross-section has been used for modelling the ultimate behaviour of multi-span masonry arch bridges. The proposed approach proves able to take into account the interaction among the spans and the non-linear material behaviour with low computational effort. In order to validate the use of the model for the assessment of masonry arch bridges, the load-carrying capacity for typical multi-span railway bridges has been evaluated and the results compared to experimental results and to currently used limit analysis methods. It is shown that, by parity of constitutive assumption, the method provides the same results as limit analysis, both in terms of maximum load prediction and hinges position at collapse; however, taking the effective ductility capacity into account, a strong reduction in load-carrying capacity with respect to classical limit analysis was found, depending on rise-to-span arch ratio, piers slenderness and backfill height. The approach is then applied to a seven span viaduct of the Italian railway network, for which the effective mechanical properties of masonry were identified through an experimental campaign on brickwork samples according to the effective material properties surveyed on site.