【作者】 王海超；

【导师】 赵国藩；

【作者基本信息】 大连理工大学 ， 结构工程， 2004， 博士

【摘要】 腐蚀环境下钢筋混凝土构件的疲劳性能，是研究工程结构耐久性问题的一个重要方面。本文作为国家自然科学基金项目(50078009)—“受腐蚀钢筋混凝土结构动力性能和可靠度研究”的一部分，进行了钢筋混凝土构件受腐蚀后的疲劳性能、腐蚀疲劳性能试验研究，分析了腐蚀疲劳断裂机理。探讨了腐蚀与疲劳的耦合作用及混凝土构件正截面腐蚀疲劳验算等方面的问题。基于试验研究结果，给出了腐蚀疲劳损伤累积发展规律和预测方法。全文共分为九章，扼要介绍如下： 第一章叙述了课题研究的工程背景，提出了钢筋混凝土构件的腐蚀疲劳问题。介绍了国内外相关的研究进展和基本结论，阐述了对相关问题的基本观点。针对存在的问题和不足，提出了本课题的研究工作内容。 第二章介绍了试验设计，包括材料的力学性能试验，试验梁的制作，静载试验和疲劳试验的加载装置等。确定了各种试验的具体实施方法、各种试验参数的选择、加载程序选定和数据采集方法等。 第三章对试验梁进行了腐蚀和预裂后的腐蚀试验，以及受腐蚀试验梁的静载和循环荷载作用下疲劳性能的试验研究。在锈蚀率很低时静承载能力没有明显的降低。但在循环荷载作用下，构件的疲劳寿命却有很大程度的下降。表明腐蚀程度相同的钢筋混凝土构件，承受动荷载要比承受静载作用危险的多。 第四章进行了钢筋混凝土试验梁在空气环境、淡水环境和盐水环境中的疲劳试验研究。叙述了环境对构件疲劳寿命的影响以及疲劳损伤的发展过程。结果表明，在腐蚀环境和循环荷载的共同作用下，梁的承载能力急剧下降，破坏形态为钢筋的迅速断裂，是一种严重的构件失效形式。腐蚀疲劳损伤的发展与环境作用的程度和循环荷载水平密切相关。 第五章实测了混凝土梁在淡水和盐水环境中，施加荷载所引起的钢筋腐蚀电位的变化。结果表明，循环荷载作用对构件钢筋的腐蚀有明显的促进作用，证实了腐蚀疲劳是腐蚀环境和循环荷载耦合作用的结果。 第六章取腐蚀疲劳试验梁中钢筋断口做扫描电镜和化学成分分析，发现钢筋断口同样存在裂纹源区、疲劳发展区、断裂区，腐蚀疲劳寿命的降低，是腐蚀介质和交变拉应力共同作用的结果，同时与构件裂缝处钢筋的复杂应力状态和裂缝所在截面的工作状态有关。这种作用加速了疲劳裂纹的萌生和扩展，并始终存在于疲劳发展直至断裂的全过程。 第七章探讨了腐蚀疲劳钢筋混凝土受弯构件正截面验算方法。针对破坏形态、极限状态、破坏准则等方面的问题提出了基本的观点，给出了确定的方法和原则。研究了构件腐蚀疲劳刚度的衰减规律。 第八章应用人工神经网络理论，建立了预测混凝土构件腐蚀疲劳刚度衰减的人工神经网络模型。应用特征展开模糊推理的数学方法，研究了混凝土构件腐蚀疲劳损伤程度的鉴别方法。大连理工大学博士论文 第九章全面总结了课题研究工作，给出了试验研究成果和理论研究的基本结论。同时提出了应当继续开展相关的课题研究工作。更多还原

【Abstract】 A study of characters of reinforced concrete members under corrosion fatigue conditions is an important aspect of engineering durability problems. In this thesis, an experimental program was carried out on fatigue properties of reinforced concrete members induced by pre-corrosion and corrosion. The fracture mechanism of corrosion fatigue for the reinforced concrete beams and the coupling action between corrosion and fatigue are analyzed. A check method of normal section of reinforced concrete members subjected to corrosion fatigue is proposed. Moreover, the development and prediction method of fatigue cumulative damage based on the test data are obtained. The thesis is an important part of the project of National Natural Science Foundation of China-Dynamical characters and reliability research of reinforced concrete structures under corrosion conditions (No. 50078009), the contents of which include nine chapters as follows.In the first chapter, the significance of this study and the relevant literatures are expounded. Meanwhile, the historical and present background of the research on corrosion fatigue of reinforced concrete is introduced systematically. Based on the existing problems, the objectives of this paper are put forward.In the second chapter, the experimental programs including the mechanics properties of materials, details of beam specimens, apparatus of static and fatigue test are introduced. Moreover, the test procedure, the test parameters and the test data acquisition method are determined.In the third chapter, experimental research is carried out on beam specimens subjected to static and cyclic loading under corrosion without pre-existed cracks, corrosion with pre-existed cracks cases respectively. The carrying capacity of beam specimens under static loading reduces a little with lower degree of corrosion, whereas, the fatigue life of beams reduces significantly under fatigue loading. It indicates that reinforced concrete members subjected to cyclic loading are more dangerous than that subjected to static loading when they are experienced the same corrosion.In the fourth chapter, experimental investigation of beam specimens is carried out subjected to cyclic loading under the conditions of air, fresh water and salt solutions respectively. The effects of conditions on fatigue life and fatigue damage evolution are analyzed. The results show that the fatigue life of beam specimens reduces significantly under corrosion conditions and fatigue loading. The fatigue damage criterion is that steel bar is ruptured rapidly, which is one of severe failuremodes of reinforced concrete members. Corrosion fatigue damage evolution is related to conditions and levels of cyclic stress.In the fifth chapter, the corrosion potential of steel bar embedded in beam specimens subjected to loading in fresh water and salt solutions is measured. Experimental results show that cycle loading accelerated the corrosion of steel bar. The conclusion that corrosion fatigue is caused by corrosion conditions and cyclic loading can be proved.In the sixth chapter, the tests of steel bar fracture extracted from the beam specimens subjected to corrosion fatigue aimed to scan electron microscopy and analyze chemical components of rupture surface are conducted. In corrosion media, cracks source region, fatigue development region and rupture region also exist on the steel bar rupture surface caused by flexural fatigue loading. The decrease of fatigue life is caused by the action of corrosion media and flexural tension stress. Meanwhile it is related to the complex stress of steel bar in cracking and the stress state of the cracking section. The actions accelerate the initial cracks emerging and spreading, which exists during the whole process from fatigue development to rupture.In the seventh chapter, the check method of normal cross-section of reinforced concrete flexural members subjected to corrosion fatigue is discussed. The determined method and principles for the failure mode, ultimate state and damage criterion etc. are更多还原