【作者】 高欣；

【导师】 欧进萍；

【作者基本信息】 哈尔滨工业大学 ， 防灾减灾工程及防护工程， 2011， 博士

【摘要】 钢管混凝土拱桥作为一种颇具中国特色且在大、中跨桥梁领域具有一定优势的桥型,在我国有着十分广阔的应用前景。但由于钢管混凝土拱桥的历史较短,以致目前国内尚未出台完整的钢管混凝土拱桥设计规范,更无成熟的使用与养护经验可供借鉴,使得在役钢管混凝土拱桥的病害现象十分复杂、桥梁事故时有发生。为了有计划地改善此类桥梁结构的服役状态,确保其安全运营,最大限度地延长桥梁的使用寿命,需要系统地研究钢管混凝土拱桥的主要病害与典型损伤的类型、关键构件的实际受力特征以及主要构件及系统的可靠性分析方法。上述研究不仅是保证我国已建成的三百余座钢管混凝土拱桥不再发生垮塌等工程事故的需要,也是保证该类具有中国特色的桥型长远发展的需要。故此,针对钢管混凝土拱桥的上述相关问题,本文主要研究了如下内容:(1)研究钢管混凝土拱桥的常见病害及其成因。分析了钢管混凝土拱桥与传统拱桥之间的差异,指出二者在结构体系、材料性能和受力特点三个方面的差异是导致钢管混凝土拱桥的病害现象、病害特征与检测方法等诸多方面有别于传统拱桥的主要原因。通过整理多座在役钢管混凝土拱桥的检测结果与病害资料,将钢管混凝土拱桥的常见病害划分为主要结构构件的病害、桥面系统的病害及附属结构的病害。进而指出,上部结构病害中的主拱肋内混凝土缺陷、吊杆与系杆的各种常见病害是钢管混凝土拱桥的典型病害,也是本文的主要研究对象。(2)研究吊杆车辆荷载效应随机性的特征以及相应的建模方法。介绍了拱桥吊杆车辆荷载效应健康监测系统。通过分析监测数据,发现吊杆车辆荷载效应具有概率密度函数形状较为复杂等特征。针对在概率密度函数较为复杂的情况下,传统方法无法建立吊杆车辆荷载效应及其极值的概率模型的问题,分别基于非参数统计学与随机过程极值理论,提出了建立吊杆车辆荷载效应概率模型的非参数统计方法和建立车辆荷载效应极值概率模型的方法。工程应用结果显示,上述方法能够很好地解决相关的建模问题。(3)研究吊杆疲劳荷载效应的特征及疲劳累积损伤的计算方法。采用雨流计数法与线性疲劳累积损伤理论,分析了吊杆疲劳荷载效应与疲劳累积损伤的特征。指出较重车辆荷载是导致吊杆疲劳累积损伤的主要荷载,其疲劳应力幅与平均应力具有近似呈线性的特点。并在此基础上,引入车辆荷载效应的概率模型,提出了非监测时段内疲劳累积损伤程度的计算方法和剩余服役期内疲劳累积损伤程度预测方法。(4)研究钢丝损伤的演化规律、吊杆抗力的衰减过程及服役可靠度的计算方法。分析钢丝的损伤演化过程,将其综合为防护失效、均匀腐蚀、裂纹扩展三个阶段。通过分析钢丝各种损伤的机理,基于损伤力学与断裂力学的基本理论,提出了钢丝名义剩余强度的计算公式。分析了吊杆抗力的衰减过程,进而采用脆性钢丝模型作为吊杆剩余承载能力的计算模型,借鉴纤维束强度计算理论给出了吊杆在抗力衰减各阶段的剩余承载能力的计算方法。将服役构件抗力的不确定性归结为构件损伤的不确定性,提出了改进的服役构件抗力衰减独立增量随机过程模型并将其应用于吊杆。(5)研究钢管混凝土拱桥的系统可靠性分析方法。通过分析现有失效模式搜索方法的优缺点及其在桥梁结构工程中的适用性,提出了适用于桥梁结构的改进的阶段临界强度分枝-约界法,解决了大型桥梁结构主要失效模式搜索的问题。比较了系统可靠度计算的区间估计法、PENT及FORM方法的适用范围,指出区间估计法主要适用于对系统可靠度区间的估计;FORM方法与PENT法分别适合系统的失效模式分组特征不明显和明显两种情况。最终,将上述系统可靠度分析方法应用于某在役钢管混凝土拱桥,分析了拱肋典型病害对钢管混凝土拱桥系统可靠性的影响。结果表明:拱顶位置处的混凝土缺陷对钢管混凝土拱桥系统可靠性的影响不容忽视。更多还原

【Abstract】 Concrete filled steel tubular (CFST) arch bridges as a type of arch bridges with Chinese characteristics have many advantages in covering middle and large spans and have a broad promising prospect in China. However, due to the short history of their development, there is no published national design standard for this bridge type, or mature maintenance techniques to refer to. This fact leads to their complicated damage phenomenon and frequent engineering accidents. In order to systematically improve the service condition and safe operation of CFST arch bridges, and maximize the bridge lifespan, it is needed to study on the main and typical damage, real mechanics characteristic of key components and reliability analysis method of main members and the system about CFST arch bridge systematically. This study will help to ensure the safety of the 300 existing bridges of the same type in China and benefit the long-term development of these bridges. Under this background, following contents of CFST arch bridges are studied in this thesis(1) Research on the commonly encountered damages and their causes in the CFST arch bridge. A comparison study was conducted to analyze the difference between CFST and the traditional arch bridges. It was found that the differences in structure system, material properties and mechanical behaviors between the CFST and the traditional arch bridge are the main reasons leading to the different damage properties and examine method in the CFST arch bridges. After a comprehensive study of the damage on some existing CFST arch bridges and the related references, the damage of CFST arch bridges is summarized and classified to three types, which are damage of the main structural components, damage of the deck system and damage of the subsidiary structures. Finally concrete defects in arch rib and commonly encountered damages in cable members are identified as typical damages in the CFST arch bridges and they are the studied objective in this thesis.(2) Research on the characteristic of the randomness of suspender traffic-load effect and its modeling method. By analyzing the monitoring data, it’s found that the probability density function (PDF) of traffic load effect is complicated. Due to the limit that traditional method couldn’t set up the probability model of traffic load effect and its extreme value when its PDF is complicated; a new method is raised based on the nonparametric statistical theory and the extreme value theory of stochastic process. The new methods are proved practical and efficient in applications for solving the modeling problem.(3) Research on the characteristic of the fatigue load effect in the suspender and its cumulative damage calculation method. The characters of fatigue load effects and cumulative damage are analyzed based on the rain flow algorithm and linear damage cumulative theory. It is found that heavy trucks are the main causes of fatigue damages of the suspenders and their fatigue stress amplitude and mean value appear to have a linear relationship with each other. Based on this, the calculation method of the damage level of suspenders in the non-monitoring period and the prediction method for their fatigue cumulative damage are raised by introducing the probabilistic model of traffic load effect.(4) Research on the damage evolution process of steel wires, the resistance deterioration process of the suspenders and the reliability calculation method for existing suspenders. The damage evolution process is divided into three stages, which are protection measure inactivation stage, uniform corrosion stage and crack propagation stage. Based on the damage mechanism of steel wire, continuum damage mechanics and fracture mechanics, the calculation method for residual strength of steel wire is raised. The resistance deterioration process analysis for suspender is analyzed. Based on the strength model of fiber bundle and brittle steel wire model, the residual load carrying capacity calculation method for suspender at different deterioration stages is proposed. By accrediting the resistance uncertainty of existing structural members to the uncertainty of components damage or fatigue, an improved independent increment process mode for resistance deterioration is presented and applied to existing suspender(5) Research on system reliability analysis method for concrete filled steel tubular arch bridge. By analyzing the advantages and disadvantages of existing failure mode searching approaches, as well as their feasibility in bridge projects, an improved branch and bound method suitable for bridges is proposed, which solves the problem on finding the main failure modes of bridge structures. With comparison of the validation range of the bound estimation method, the PNET method and the FORM method, it is pointed out that the bound estimation method applies to estimating system reliability bound while the PNET and the FORM methods are respectively appropriate for the situations with and without obvious group characteristics. Finally, all the system reliability analysis methods are applied to an existing CFST arch bridge., in which the influence of typical arch rib damage to the system reliability of bridge is analyzed. The result of the analysis showers that influence of concrete imperfection to the system reliability of the bridge is not neglected.更多还原