混凝土桥梁检测与加固技术的有效措施

混凝土桥梁检测工作能够帮助工作人员了解混凝土桥梁的损伤程度,从而保障桥梁的通行安全。本文基于混凝土桥梁检测工作的重要性,介绍了混凝土桥梁检测工作的内容、方法及检测措施,并探讨了针对混凝土桥梁表层、上部结构、下部结构等方面的加固技术,为相关施工人员提供借鉴。     

农村公路桥梁养护管理的思考

结合海南农村公路桥梁的现状情况,通过对桥梁病害原因的分析,阐述了农村公路桥梁在养护管理过程中存在的问题,并就如何做好农村公路桥梁养护管理提出了具体的建议,以提高农村公路桥梁的技术状况和安全水平。     

桥梁裂缝监测系统研究与应用

针对现有混凝土桥梁裂缝监测方法中存在的问题,设计了基于机敏网的混凝土桥梁结构裂缝实时监测系统,研究了机敏网监测裂缝的基本原理,裂缝监测系统的组成,并进行了相关实验和工程应用。混凝土桥梁结构裂缝监测系统能实时地监测混凝土结构的实际损伤情况,灵敏度高,可靠性好。可广泛应用于桥梁、水坝和其他大型混凝土结构的损伤监测。     

预防北京地区混凝土碱骨料反应的技术措施

1 前言 近年来,在北京早期建造的城市桥梁混凝土中,低耐久性的破坏引起有关专家的重视,为了弄清北京现有桥梁混凝土是否存在碱骨料反应这一问题。从1991年开始,北京市政工程研究院对北京70年代末至80年代中期修建的某些立交桥进行了追踪调查。从受损伤桥梁混凝土构件的实体上取样,通过混凝土薄片观察、能谱分析和混凝土膨胀性试验,证明所调查的几座受损伤城市桥梁混凝土构件,均发生了碱硅酸反应,并且是导致这些混凝土桥梁耐久性不良的主要原因[1]。     

公路混凝土桥梁损伤评估技术探讨

对桥梁损伤实现准确的评估和预测,对于桥梁的养护和维修工作,保证桥梁长期稳定使用,具有深远的现实意义。现阶段,国内外行业人员对此给予高度重视并积极进行研究和探讨。通过对公路混凝土桥梁损伤评估技术进行研究分析,主要阐述公路混凝土桥梁损伤评估中的相关问题,以此延长桥梁的使用时间。     

农村公路桥梁桩基设计问题分析

现今大多数农村公路桥梁的基础都是选用桩基础,桩基设计的合理与否对公路桥梁的整体质量有很大的影响,对工程造价和工期也有不同程度的影响。所以,在进行公路桥梁建设时,要注重桩基设计的有关问题。本文从农村公路的特点和桥梁桩基设计的合理性和经济性出发,从桩基承载力、嵌岩深度、桩基配筋、桩基负摩阻力等方面对农村公路桥梁桩基设计问题进行了分析。     

耐候钢在农村公路桥梁应用中的思考和探索

分析了耐候钢在农村公路桥梁中的应用现状,介绍了耐候钢材料的特性,并结合工程实例,研究了其在工程中的应用成效、技术优势及存在的问题,思考探索了其在农村公路桥梁上的应用前景。     

预应力混凝土桥梁的耐久性研究

介绍我国预应力混凝土桥梁的发展状况和国外预应力混凝土桥梁的耐久性问题及其研究进展情况,对预应力桥梁结构耐久性受到构件混凝土开裂及钢筋锈蚀、混凝土徐变和预应力钢筋松弛致使的预应力损失、重复荷载引起的疲劳损伤等影响因素进行了分析。     

浅谈农村公路桥梁养护及管理措施

农村公路桥梁的改善是解决“三农”问题的重要前提和基础条件，是广大农村地区重要的交通基础设施，其技术状况的好坏直接影响着农村交通运输的安全，制约着农村经济的发展。对农村公路桥梁现状进行了分析，指出了农村公路桥梁养护管理存在的问题并提出了应对措施。     

桥梁混凝土结构病害分析及处治

桥梁混凝土结构在修建或运营一段时间后往往会伴有病害的发生,如混凝土开裂、钢筋诱蚀等,对混凝土桥梁产生不同程度的损伤,影响结构的正常使用,降低其使用性能及使用寿命。本文主要分析了桥梁混凝土结构的常见病害,并提出了一些病害处治措施。     

非一致氯离子侵蚀下近海桥梁时变地震易损性研究

近海桥梁往往处于氯离子空间分布不均匀的复杂环境,在服役过程中往往会遭受非一致氯离子侵蚀,导致材料及结构性能不断退化,降低桥梁抵御地震的能力。为研究非一致氯离子侵蚀下桥梁地震损伤风险变化规律,文章以氯离子扩散规律及钢筋锈蚀机理为基础,基于Duracrete模型及以往试验结果,确定不同环境参数及锈蚀参数的概率分布类型及统计特征,建立钢筋及混凝土材料退化规律。结合地震易损性分析理论,建立非一致氯离子侵蚀环境下桥梁时变地震易损性评估流程。随后,以一座多跨连续梁桥为例,分析退化桥梁抗震能力变化特征,研究不同构件的地震损伤时变规律。研究结果表明,氯离子侵蚀下的桥墩截面抗弯承载力和曲率延性均表现出明显的退化,并且曲率延性退化程度高于抗弯承载力。非一致氯离子侵蚀会导致桥墩损伤分布发生演变,桥墩易损位置可能从墩顶、墩底转移至低水位处。随着服役时间增加,桥墩损伤概率明显增大,而支座、挡块及桥台的损伤概率略有降低。     

沿海桥梁混凝土结构腐蚀调查及分析

针对日照沿海桥梁的耐久性现状进行调研,通过对桥梁墩身、边梁和栏杆混凝土的保护层厚度、碳化深度以及桥梁不同部位的游离氯离子浓度的检测表明:桥梁混凝土结构保护层厚度偏小、车辆超载、结构设计不合理、施工管理不当、缺乏维护管理是导致沿海桥梁混凝土结构损伤劣化的主要原因。此外,海洋环境中的氯离子和空气中的二氧化碳将导致桥梁混凝土中钢筋腐蚀,海水中的盐在混凝土中结晶将导致桥梁墩身腐蚀破坏。     

Reliability-based optimisation design of post-tensioned concrete box girder bridges considering pitting corrosion attack

Since the mid-twentieth century, prestressed concrete (PC) bridges have been significantly developed to become the most important type of bridge in the world. However, only a few studies have dealt with the reliability-based design optimisation (RBDO) of PC bridges despite the fact that RBDO demonstrates the real behaviour of structures. Moreover, the corrosion of post-tensioned tendon in PC bridges seriously caused sudden failures which have been recorded in the world. Since then, this study presents the probabilistic model and approach to formulate and analyse the RBDO of PC box girder bridges which consider the pitting corrosion phenomenon of shear, torsion reinforcements and post-tensioned tendon. A practical example of a typical PC box girder bridge is presented and discussed. Sensitive analyses are performed to evaluate the influence of ultimate target reliability index on the optimal solution. For the simple support PC box girder bridge, the ultimate target reliability index should be in the range of β_ult: 3.5–5 in order to produce the optimal design.     

提高钢筋混凝土桥梁耐久性的措施研究

钢筋混凝土桥梁的腐蚀与劣化是桥梁运营中的一个不容忽视的问题,对既有桥梁进行病害检测与修复是提高其耐久性的必要措施,文中阐述了桥梁工程中钢筋及混凝土的腐蚀机理,分析了不同的病害原因,并制定了针对性的修补措施,提出对桥梁要进行整体保护。     

Life-cycle evaluation of deteriorated structural performance of neutralised reinforced concrete bridges

For existing reinforced concrete (RC) bridges, the structural performance is highly dependent on the changing properties of concrete and reinforcing steel due to neutralisation-induced corrosion. As neutralisation progresses, the corrosion could become serious enough to deteriorate not only the serviceability, but also the maintainability, of the structural performance. To study the influence of neutralisation on the existing RC bridges, the inspected data and test results collected from 21 bridges in Taiwan were examined to obtain the essential parameters through regression analyses. The regressive parameters related to service time can be employed in evaluating the variation of material and sectional properties in both reinforcements and concrete, and, accordingly, the change of structural performance from time to time could be obtained quantitatively via structural analysis. As a consequence, the performance degradation curve of an existing RC bridge can be predicted and, if necessary, the appropriate timing for repair or retrofit could be suggested. The results obtained could facilitate the minimisation of life-cycle cost for the neutralised RC bridges and enhance the functionality of a bridge management system (BMS).     

Seismic fragility estimates for corroding reinforced concrete bridges

Seismic fragility of reinforced concrete (RC) bridges is defined as the conditional probability that the seismic demand exceeds the corresponding capacity, specified for a certain performance level, for given seismic intensity measures. However, the structural properties of RC bridges change over time due to the onset of corrosion in the reinforcing steel. Therefore, seismic fragility of RC bridges changes during a bridge lifetime. This paper proposes a method to estimate the seismic fragility of corroding RC bridges. Structural capacities are defined using probabilistic models for deformation and shear capacities of RC columns. Probabilistic models are also used to estimate the corresponding demands for given seismic intensity measures. The capacity and demand models are then combined with probabilistic models for chloride-induced corrosion and time-dependent corrosion rate to model the dependency on time of the seismic fragility of RC bridges. In particular, the loss of reinforcing steel is modelled as a function of the thickness of the cover concrete for each reinforcing bar in the RC columns. The stiffness degradation in the cover concrete over time due to corrosion-induced cracking is also considered in the fragility estimates. Seismic fragility estimates are then formulated at the column, bent, and bridge levels. The fragility formulations properly incorporate the uncertainties in the capacity and demand models, and the inexactness (or model error) in modelling the material deterioration. The proposed method accounts for the variation of structural capacity and seismic demand over time due to the effects of corrosion in the reinforcing steel. As an application, seismic fragility estimates are developed for a corroding RC bridge with 11 two-column bents over a 100-year period.     

海洋环境下混凝土结构破坏与涂层防护

从腐蚀破坏形式、腐蚀破坏危害及涂层防护3个方面对海洋环境下混凝土结构进行探讨分析。首先讲述了混凝土腐蚀破坏形式;然后结合沿海地区混凝土桥梁的破坏案例,分析说明了混凝土结构破坏带来的危害;最后结合混凝土本身性质和使用环境讲述了混凝土结构的防护、涂层防护分类及各种涂层的优点,重点讲述了聚脲涂层的优良性能及在海洋环境下混凝土结构的防护应用。     

Robustness of corroded reinforced concrete structures – a structural performance approach

The aim of this work is to provide new contributions in order to define more accurately the structural robustness concept, particularly when applied to corroded reinforced concrete (RC) structures. To fulfil such a task, several robustness indicators are analysed and discussed with special emphasis on structural-performance-based measures. A new robustness definition and a framework are then proposed for its analysis, based on the structural performance lost after damage occurrence. The competence of the proposed methodology is then tested comparing the robustness of two RC foot bridges under corrosion. The damage considered is the longitudinal reinforcement corrosion level, and load carrying capacity is the structural performance evaluated. In order to analyse corrosion effects, a finite element (FE) based on a two-step analysis is adopted. In the first step, a cross-section analysis is performed to capture phenomenons such as expansion of the reinforcement due to the corrosion products accumulation; damage and cracking in the reinforcement surrounding concrete; steel–concrete bond strength degradation; effective reinforcement area reduction. The results obtained are then used to build a 2D structural model, in order to assess the maximum load carrying capacity of the corroded structure. For each foot bridge, robustness is assessed using the proposed methodology.     

面向未来的高性能桥梁结构研发与应用

为从根本上解决混凝土桥、钢桥及钢 混凝土组合桥中的共性技术难题,并提升桥梁结构的性能与品质,笔者团队以超高性能混凝土（UHPC）为基础,研发了面向未来的高性能桥梁结构体系。介绍了笔者团队研发的4类高性能桥梁结构:①钢-超高韧性混凝土（STC）轻型组合桥面结构,其中的STC是钢桥面专用的UHPC;②钢 UHPC华夫板轻型组合桥梁结构;③单向预应力UHPC薄壁连续箱梁结构;④全预制快速架设UHPC城市桥梁结构。通过大量静力和疲劳试验,掌握了各类UHPC桥梁结构的基本受力性能,并建立了计算理论和设计方法。列举了钢 STC轻型组合桥面结构已推广应用于中国的17座钢桥,涵盖了梁桥、拱桥、斜拉桥和悬索桥等各类基本桥型,典型应用包括湖南岳阳洞庭湖二桥等重大工程。到目前为止,各实桥运营状态良好,钢 STC未出现任何病害问题。综合而言,高性能桥梁结构有望突破现有桥梁中的技术瓶颈,具有广阔的应用前景。     

浅析海洋环境下桥梁防腐蚀设计

随着经济的发展,在海洋环境下建设的桥梁越来越多,桥梁结构的防腐蚀及耐久性设计已成为关键性的技术问题,文中分析钢筋混凝土结构在海洋环境下的受腐蚀机理,并通过工程实例探讨桥梁各结构部位应采取的具体防腐蚀措施.