摘要
为促进桥梁长寿命设计理论的发展,从桥梁服役寿命及其影响机理出发,总结了现有桥梁长寿命设计的研究现状和面临的主要问题,探讨了未来研究重点和方向.研究结果表明:现行各国规范根据桥梁重要性及其所在公路等级进行桥梁设计寿命的规定,多采用变寿命的设计思路,赋予不同功能、重要程度、更换难度的桥梁构、部件不同的设计寿命;桥梁的寿命取决于其在真实服役环境下的长期性能,包含环境侵蚀作用下的耐久性能、反复荷载作用下的疲劳性能和持续荷载作用下的徐变性能,受服役环境、养护干预和施工过程的影响显著;新建桥梁长寿命技术主要从设计方法和高性能材料展开研究,现有服役寿命和耐久性设计方法主要围绕环境作用、劣化机理、材料性能、施工控制和检查管理等方面,达到了"看似满足"的设计目标,尚未能实现概率水平提升和设计寿命量化,全寿命设计则还停留在理念层面,UHPC、耐候钢、FRP等高性能材料的应用是提升桥梁设计寿命的有效方式;未来应以"明确结构定位,完善性能指标体系,优化结构初始状态,改善服役微环境,控制劣化传递路径"为长寿命设计的基本框架,围绕桥梁结构的长寿基因识别与调控、桥梁微环境全寿命周期演化规律、桥梁服役寿命的全概率量化设计方法等基础理论开展研究,以建立系统的桥梁长寿命设计理论体系.
Abstract
To promote the development of long-life design theory for bridges,the service life of bridges and the influencing mechanisms were studied,the current research status and main problems faced in the long-life design of existing bridges were summarized,and the future research focuses and directions were discussed.Research results show that current specifications in different countries determine the design life of bridges based on bridge importance and highway class,and they follow a variable life design idea to assign different design lives to bridge elements and components with different functions,importances,and replacement difficulties.The life of a bridge depends on its long-term performance in the actual service environment,including durability under environmental erosion,fatigue under repeated loading,and creep property under sustained loading,and it is significantly influenced by the service environments,maintenance interventions,and construction processes.The research on long-life technologies for new bridges mainly focuses on design methods and high-performance materials.Existing service life and durability design methods mainly study environmental actions,degradation mechanisms,material performances,construction control,and inspection management,achieving the design goal of"deemed-to-satisfy",but they do not achieve improvement on the probabilistic level and quantification of design life.The life cycle design still remains at the conceptual level.The application of high-performance materials,such as ultra-high performance concrete(UHPC),weathering steel,and fiber reinforced polymer(FRP),is an effective way to improve the design life of bridges.In order to establish a systematic theory system for the long-life design of bridges,future research should adhere to the basic framework of long-life design,including defining structural positioning,improving performance indicator system,optimizing initial structural condition,improving service micro-environment,and controlling degradation transmission paths.Research should also be conducted on the identification and regulation of long-life genes of bridge structures,evolutionary laws of bridge micro-environments in the life cycle,and fully probabilistic quantification design methods for the service life of bridges.6 tabs,28 figs,96 refs.
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