超载车辆和环境腐蚀作用下波形钢腹板组合箱梁桥的疲劳性能评估

Overloaded vehicles and environmental corrosion have become the main reasons for accelerating the fatigue damage accumulation and shortening the life of steel structure bridges. The scientific and rational assessment for fatigue damage and fatigue life of steel structure bridges is critical for ensuring the safety bridge of service. The composite box girder bridge with corrugated steel webs (CSWs) as a new type of steel structure bridge has developed rapidly in recent years, but the research about its fatigue performance is not sufficient. Therefore, this project aims to study the fatigue performance of the composite box girder bridge with CSWs under the effects of overloaded vehicles and environmental corrosion. Fatigue stress spectrum of the key structural details of this type of bridge will be studied under the action of overloaded vehicles through refined bridge-vehicle coupled vibration analysis. Equivalent section models of the composite box girder bridge with CSWs will be fabricated, and "fatigue-corrosion-fatigue" cyclic fatigue tests for models will be carried on considering the effects of overloaded vehicles and environmental corrosion in order to study the fatigue damage mechanism. Considering the S-N curve obtained from fatigue tests and fatigue stress concentration factor of the key structural details, scientific and reasonable assessment of fatigue life and fatigue performance of composite box girder bridge with CSWs will be performed. The research results will provide reasonable supplement for the fatigue design of the composite box girder bridge with CSWs in Chinese Specifications, and it also can provide important theoretical basis and scientific support for the design, construction and maintenance of this type of bridge in the future.

车辆超载运输和环境腐蚀已成为钢结构桥梁疲劳损伤加速、使用寿命缩短的主要原因。对钢结构桥梁的疲劳损伤及疲劳寿命进行科学合理的评估对确保桥梁服役安全具有重要意义。波形钢腹板组合箱梁桥作为一种新型的钢结构桥梁近年来发展迅速，但目前对其疲劳性能的了解和研究尚不充分。为此，本项目拟对超载车辆和环境腐蚀作用下波形钢腹板组合箱梁桥的疲劳性能展开研究。基于车桥耦合振动精细化模型对超载车辆作用下该桥型关键构造细节的疲劳应力谱进行研究；设计制作波形钢腹板组合箱梁桥的等效节段模型，在考虑超载车辆和环境腐蚀作用下对其进行“疲劳-腐蚀-疲劳”的循环疲劳试验，研究其疲劳损伤机理；结合疲劳试验所得的S-N曲线及关键构造细节的疲劳应力集中系数，对波形钢腹板组合箱梁桥的疲劳寿命及性能做出科学合理评估。研究成果是我国现行规范中波形钢腹板组合箱梁桥疲劳设计的合理补充，将为该桥型的设计、建造和维护提供重要的理论依据和科学支撑。

波形钢腹板组合箱梁桥具有诸多优点，近年来在国内外的桥梁建设中得到快速发展。为确保波形钢腹板组合箱梁桥的运营安全，本项目对超载车辆和环境腐蚀作用下波形钢腹板组合箱梁桥的疲劳性能开展研究，研究内容主要包括：1）波形钢腹板组合箱梁桥关键构造细节的疲劳应力幅谱确定；2）超载车辆和环境腐蚀作用下波形钢腹板组合箱梁桥的疲劳损伤机理研究；3）超载车辆与环境腐蚀作用下波形钢腹板组合箱梁桥的疲劳寿命预测。研究重要结果有：1）根据已有文献统计出了我国标准疲劳车模型，建立了6轴标准疲劳车辆设计荷载的数值计算模型；2）明确了波形钢腹板组合箱梁桥关键部位的疲劳细节分类方法，并对疲劳细节的静、动应力、应力幅及疲劳累积损伤进行了计算分析，建立了该桥型的疲劳损伤模型；3）编制了波形钢腹板组合箱梁桥的车-桥耦合振动系统精确疲劳应力计算程序，求解了关键构件疲劳细节的应力幅值及对应的应力幅循环次数，确定了关键构造细节的疲劳应力幅谱；4）明确了车辆和环境腐蚀作用下波形钢腹板组合箱梁桥的疲劳损伤机理，提出了考虑路面腐蚀劣化下波形钢腹板组合箱梁桥的疲劳冲击系数的设计取值和考虑伸缩缝破损及路面腐蚀劣化下波形钢腹板组合箱梁桥疲劳冲击系数的计算公式；5）编制了基于车-桥耦合振动的波形钢腹板组合箱梁桥疲劳性能及疲劳寿命评估分析系统计算程序，提出了基于目标疲劳可靠指标下波形钢腹板组合箱梁桥细节疲劳寿命的计算方法。本项目对波形钢腹板组合箱梁桥在超载车辆和环境腐蚀作用下的疲劳损伤机理进行了研究，并对其疲劳寿命进行了准确评估，不仅可以有效地防止此类桥梁疲劳破坏事故的发生，合理延长其使用寿命与维护周期，并且对提高我国现代钢桥的设计和制造水平也具有非常重要的意义。本项目的研究成果完善了钢桥设计理论，是对我国现行规范中波形钢腹板组合箱梁桥抗疲劳设计的合理补充，可为我国该桥型的疲劳设计、建造和运营维护提供理论依据和科学支撑。

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