Fatigue Durability of Concrete Bridge Decks

Victor Li， University of michigan这项研究针对的是混凝土桥面的疲劳耐久性。最近的研究表明，疲劳开裂可能是混凝土桥墩严重破坏的前兆。目前人们对桥面疲劳损伤的基本原理和相应的补救措施知之甚少。本研究的重点是对混凝土桥面疲劳耐久性的基本认识和使用纤维增强混凝土桥面疲劳耐久性的研究。由于纤维增强混凝土（FRC）的抗疲劳性能在实验室中有大量的文献记录，因此纤维增强尤其受到关注。采用基于统计/细观力学的理论模型，分析了疲劳荷载作用下的裂纹扩展机理，以及循环荷载作用下混凝土裂缝上的骨料和纤维桥接响应。此外，根据实验观察，明确地解释了纤维/水泥和骨料/水泥界面的降解。本研究的四个重要结论是：1)针对疲劳损伤的桥梁面板设计方法；2)对FRC疲劳破坏机理的基本认识；3)基于细观力学的FRC抗疲劳复合材料设计模型；4)使用FRC的桥面评估/修复程序。这一研究导致了基于机理的结构性能设计，迫使材料与结构工程之间紧密联系。采用实验与理论相结合的方法。着重介绍了桥面性能的现场数据和疲劳试件的室内数据。这项研究的性质需要结合桥梁工程和复合材料工程的知识。

Victor Li, University of MichiganThe investigation addresses the fatigue durability of concrete bridge decks. Recent research suggests that the fatigue cracking can be a precursor to severe failure of concrete bridge docks. The fundmentals of fatigue damage and corresponding remedial action on bridge decks are currently poorly understood. This investigation focuses on basic understanding of fatigue durability of concrete bridge decks and on fatigue durability enhancement by the use of fiber reinforcement. fiber reinforcement is especially focused on because of the extensive documentation of fatigue resistance enhancement of fiber reinforced concrete (FRC) in laboratory. The mechanism of crack growth under fatigue loading, and aggregated and fiber bridging (across a concrete crack) response subjected to cyclic loading, are analyzed with a statistical/micromechanics based theoretical model. In addition, the degradation of the fiber/cement and aggregate/cement interface are expilicitly accounted for based on experimental observations.Four important consequences of this research are:1) Bridge deck slab design procedure against fatigue damage; 2) Fundamental understanding of the mechanisms governing fatigue failure of FRC; 3) Micromechanics based model for design of fatigue resistance FRC composites; and 4) Evaluation/repair procedure of brige decks using FRC. This research leads to mechanism based structural performance design forcing a tight connection between materials and structural engineering. The approach adopted is combination of experimental and theoretical work. Field data of bridge deck performance and laboratory data of fatigue specimens are emphasized. The nature of this reseach requires combined knowledge of bridge engineering as well as composite materials engineering.