钢筋混凝土梁疲劳状态演变的残余应变特征指标研究

Fatigue damage which belongs to brittle fracture cause serious consequences. Study on the process of structure fatigue, can do early warning and avoid catastrophic events.This project, from the study of concrete crack tip damage, stress and strain relation under fatigue loading, fully excavate the mutual relations of the mechanical behavior of concrete micro fracture and macro fracture mechanics mechanism, at the same time, obtain the relationship between the concrete crack tip damage degree and state of fatigue, accumulated residual strain, and finally get to the calculation model of the residual strain of concrete material which characterizes fatigue state; Taking into account the simple plain concrete structure is not much, and often there will be reinforced to participate in force, through extensive research on influence for concrete crack tip owing to bond performance degradation, this basic bending component as example, this project analysis the process of fatigue state evolution of reinforced concrete beam, and verify the research results by the fatigue test and the data of real-time monitoring. The research results of this project is expected to lay a solid foundation to determine the fatigue state of reinforced concrete structure for the service.

疲劳破坏属于脆性破坏，一旦发生后果严重。对结构或构件的疲劳过程展开研究，能做到提前预警，避免灾难事故的发生。本项目从研究疲劳荷载下混凝土裂尖损伤、应力-应变场关系出发，在充分挖掘混凝土微观断裂力学行为与宏观断裂力学机理相互关系基础上，进一步获取混凝土裂尖损伤程度与其疲劳状态、累积残余应变的关系，最终得到能表征混凝土材料疲劳状态的残余应变计算模型；考虑到单纯的素混凝土结构并不多，往往还会有钢筋参与受力，通过广泛开展因粘结性能退化对混凝土裂尖的影响研究，以梁这一基本受弯构件为例，分析有钢筋参与的混凝土梁疲劳状态演变过程，同时结合疲劳试验和实时监测数据进行验证。本项目研究成果可望为服役的钢筋混凝土结构疲劳状态的确定打下坚实基础。

混凝土桥梁往往不可避免地存在某些细小结构缺陷，这些缺陷大多以微观裂纹形式出现，在长时间的结构服役期内，由于环境的侵蚀、材料的老化及自然灾害，加之交通荷载的反复疲劳作用，因这些细小缺陷引起的疲劳损伤不断累积，导致桥梁结构整体抵抗自然灾害，甚至正常服役荷载的能力逐渐下降。本项目从研究疲劳荷载下混凝土裂尖损伤、应力-应变场关系出发，在充分挖掘混凝土微观断裂力学行为与宏观断裂力学机理相互关系基础上，获取了混凝土裂尖损伤程度与其疲劳状态、累积残余应变的关系，得到了能表征混凝土材料疲劳状态的残余应变计算模型；考虑到单纯的素混凝土结构并不多，往往还会有钢筋参与受力，通过广泛开展因粘结性能退化对混凝土裂尖的影响研究，以梁这一基本受弯构件为例，分析了有钢筋参与的混凝土梁疲劳状态演变过程，同时结合疲劳试验和实时监测数据给予了验证。