既有铁路钢筋混凝土梁桥动态可靠性评估

介绍了既有桥梁结构的动态可靠性分析方法,提出了桥梁的恒载概率模型、活载概率模型及抗力概率模型,并对可靠度计算方法中的验算点法进行了介绍。以一座既有铁路钢筋混凝土梁桥为工程背景,计算了该桥的活载效应统计参数、恒载效应统计参数及抗力统计参数等,利用验算点法计算了桥梁结构构件的可靠度指标,又采用PNET方法分析了整个桥梁体系的可靠性,最后给出了桥梁的可靠性评估结果。结果显示动态可靠性评估应用于铁路钢筋混凝土梁桥可以得到较好的评估结果。     

现役钢筋混凝土拱桥荷载试验研究

介绍了大跨径钢筋混凝土拱桥的荷载试验,对试验结果和理论值进行了比较分析,评估桥梁整体承载力和工作性能现状.以期为既有桥梁的健康状况评估、承载能力分析、破损维护与加固提供依据.     

某空心板桥常规检测与评估

对既有桥梁进行定期常规健康检测可以了解桥梁结构当前技术状态,对桥梁的安全性、可靠性、耐久性作出合理评价,提出处治措施与建议,保证桥梁的安全运营。文章通过工程实例介绍了简支空心板桥的常规检测。     

在役混凝土桥梁结构的动态可靠性评估分析

介绍了钢筋混凝土桥梁构件的动态可靠性评估方法,初步分析了荷载效应概率模型、结构抗力概率模型以及抗力的影响因素,提出动态可靠性理论也可以作为可靠性的预测方法,可以使人们获得任意时点的可靠度,从而应用于桥梁结构的可靠性评估.     

基于可靠性的桥梁评估方法

从桥梁的可靠性出发，介绍了桥梁评估的内容，从桥梁的安全性、耐久性、适用性等方面进行了论述，指出桥梁可靠度的评价，对桥梁的工程质量起着非常重要的作用。     

桥梁评估方法的研究现状与发展

对桥梁评估方法研究的现状进行系统的总结与评述,并针对现有的桥梁技术状况和既有桥梁评估本身特点,探讨适合于目前现状的桥梁评估方法以及存在的问题,认为基于设计规范的方法比较适用于桥梁承载能力评估,模糊理论与神经网络相结合的方法较适合于桥梁状态评估,但仍需要进行大量的研究工作和实际应用来进一步完善和改进.     

现有桥梁剩余寿命预测方法研究

综合考察日前的桥梁评估与寿命预测的技术研究,介绍了基于可靠性理论的桥梁评估方法、剩余寿命预测方法。     

基于GUI技术既有建筑物可靠性评估软件的开发

随着我国建筑业发展,对既有建筑物进行可靠性评估的工作日益重要,为开发可独立运行的评估软件。根据既有建筑物结构特点,结合分级评定的原则建立了既有建筑物可靠性评估体系,采用神经网络技术来进行可靠性评估工作,同时结合GUI技术完成可视化界面设计。     

地铁隧道穿越既有桥梁安全风险评估及控制

 由于城市地铁建设的不确定性和桥梁结构的复杂性,导致城市地铁工程邻近桥梁施工安全风险的显著增加。针对地铁施工对邻近既有桥梁的安全影响问题,建立包含工前检测、工前评估、工中动态控制、工后评估及恢复等四个方面的既有桥梁安全风险评估及控制体系,即识别可能存在的风险,提出地铁施工过程中既有桥梁施工中的控制指标及控制标准,关键是既有桥梁所能承受的最大差异沉降量;综合应用注浆加固及主动顶升等措施,利用信息化手段实现既有桥梁在全过程中的安全性;通过对施工结束后施工数据的分析,对既有桥梁结构进行必要性评估及恢复。将该成果应用于北京地铁6号线穿越花园桥施工过程中,结果表明,穿越施工风险控制达到了预期的控制目标,实现了既有桥梁在隧道施工过程中的安全运营。     

钢筋混凝土桥梁结构耐久性的评估方法研究

随着当前大量既有钢筋混凝土桥梁结构耐久性问题越来越突出,对耐久性评估方法的研究已引起行业内和工程界的普遍关注.本文阐述既有桥梁结构耐久性评估的定义、内容,总结目前既有桥梁结构耐久性评估的方法.然后建立既有钢筋混凝土桥梁结构耐久性的模糊综合评估模型并应用于工程实际,本方法可用于多种类型的桥梁评估,具有普遍性.     

System reliability of suspension bridges

Provisions for the design of existing suspension bridges often rely on a deterministic basis. Consequently, the reliability of these bridges cannot be assessed if current provisions are applied. In order to develop cost-effective design and maintenance strategies for suspension bridges a system reliability-based approach has to be used. This is accomplished by a probabilistic finite element geometrically nonlinear analysis approach. This study forms part of an investigation into the system reliability evaluation of geometrically nonlinear large span bridges recently undertaken at the University of Colorado. A brief review of reliability analysis of geometrically nonlinear elastic structures allows for the determination of its relevance to the assessment of suspension bridges. A probabilistic finite element geometrically nonlinear elastic code is used for system reliability evaluation of suspension structures. The allowable stress design procedures used by the Honshu Shikoku Bridge Authority for the design of suspension bridges are presented along with their application to the design of an existing bridge. This bridge is studied from a system reliability viewpoint to evaluate its reliability under different loading and damage scenarios. Such information calls attention to the fact that the reliability of cables, hanger ropes and girders are very different. Therefore, optimal maintenance decisions for suspension bridges designed according to allowable stress method are not consistent with those based on equal component reliability values.     

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.     

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.     

谈既有房屋结构可靠性鉴定

从既有房屋结构可靠性定义、既有结构鉴定依据、方法,可靠性评定目的及内容,可靠性鉴定存在的缺陷及发展方向等方面进行论述,对既有建筑可靠性评定的研究有着非常广泛和深刻的社会意义。     

System reliability models for bridges

There is a need for efficient bridge evaluation procedures. A considerable number of existing bridges in the United States require repair and/or replacement. Accurate estimate of the current strength and the remaining life time is essential for optimum distribution of the available limited resources. The major parameters which determine the structural performance are random variables. Statistical models of load and resistance can be derived from the test data, observations and analysis. For bridge members the reliability can be calculated using this available data, observations and analysis. considerable discrepancy between the reliability level of individual members and the overall bridge reliability. Due to load sharing and redundancies, the actual load-carrying capacity often exceeds the theoretical value. System reliability methods allow us to reveal an actual safety reserve in the structure. This paper summarizes the practical bridge reliability models. Using a special sampling technique, the reliability is evaluated for typical girder bridges.     

Inspection and evaluation methods on dynamic performance of highway bridges under moving vehicular loads

This paper is concerned with the inspection and evaluation methods on dynamic performance of highway bridges under moving vehicular loads. The background and development process of the existing specifications are stated and discussed. Up to now, four specifications or drafts for approval related to dynamic performance inspection and evaluation have been published. The deficiencies of the existing specifications are discussed and the differences among them are compared, including dynamic loading test methods, data processing, and evaluation criteria. Finally, some key research topics about the inspection and evaluation methods on dynamic performance of highway bridges are proposed.     

Bridge performance indicators based on traffic load monitoring

The assessment of the existing road bridges as a part of bridge management networks has been a subject of several European research projects and actions in the last few decades. Bridge management includes a series of activities, interconnected in order to achieve optimal balancing of required costs, potential risks and overall bridge performance. This paper discusses a valuable link between a specific indicator (traffic load information calculated using Bridge Weigh-in-Motion measurement data) and the corresponding structural performance (reliability of existing bridge). It is shown that implementation of weigh-in-motion measurements in the probabilistic assessment of existing road bridges can reveal hidden bridge reserves and predict bridge reliability development over the required lifetime. Consequently, such approach can yield an unrestricted use of the bridge over a much longer remaining service life. Broader advantages lie in an improved road network management, road bridges in particular, and in a more sustainable development of infrastructure network and greater satisfaction of road users and owners.     

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.     

现有铁路钢桥的评估

对现有铁路钢桥进行一系列的动力试验、加速度测量、评估、有限元模拟和安全指数计算。采用专门列车进行动力试验,并获取动力参数。这些参数还可用于建立桥梁的有限元模型。如果模型能够反映实际工况,就能用于计算每种工况下桥梁结构的安全指数。这些安全指数可用于计算杆件的破坏可能性,因此可采用本模型评估桥梁的可靠性。通过了解现有桥梁结构的实际工况,本研究可为新的货运列车重级荷载研究提供可靠依据。     

Assessment of existing steel railway bridges

A series of dynamic tests, acceleration measurements, evaluation, finite element model simulations and safety index calculations were performed on existing steel railway bridges giving service on railway network. Dynamic tests were fulfilled by using a special test train on these bridges to obtain the dynamic parameters and these parameters were then used to refine the finite element models of the bridges. Once the models have been updated to represent the actual condition, safety indices were calculated for structural components of the bridges for each proposed loading condition. These safety indices were used to calculate failure probabilities of structural members. As the final step, system reliability of the bridges was evaluated based on proposed system models of the bridges. It is believed that this study will provide a reliable background for proposed heavier axle loads resulting from new freight trains by realizing the current condition of bridge structures.