摘要
以预应力纤维增强复合材料(FRP)片材加固钢筋混凝土(RC)梁为研究对象,探讨了该类加固梁中FRP与混凝土之间界面疲劳裂纹的扩展规律。基于界面裂纹尖端的力学分析模型,理论推导了三点弯曲加固梁的界面裂纹应力强度因子(SIF)的计算公式,分析了FRP预应力水平对SIF的影响,并结合加固梁的界面裂纹扩展实验,提出了该类加固梁界面疲劳裂纹扩展速率的半经验公式。研究结果表明:加固梁的界面疲劳裂纹扩展可分为裂纹快速扩展、稳定扩展及失稳扩展3个阶段;在加固梁失稳破坏之前,界面疲劳裂纹的扩展速率可以Paris公式的形式表示;SIF在加固梁跨中界面起裂时具有最大值,随着界面裂纹长度的增大而减小;在受拉钢筋弹性变形的范围内,与无预应力FRP加固梁相比,预应力FRP加固梁界面裂纹的SIF明显偏大。
The propagation behavior of interface fatigue crack in reinforced concrete（RC） beam strengthened with prestressed fiber reinforced polymer（FRP） was studied.The mechanical analysis model was established for the interface crack tip in the strengthened beam under three-point bending.The theoretical derivation of stress intensity factor（SIF） for the interface crack was presented base on the mechanical model,and the effect of the prestress level on SIF was discussed.Combined with the experiments on interface fatigue crack propagation rate,a semi-empirical formula was developed for the propagation rate of interface crack in such strengthened beams.Results showed that the propagation of the interfacial fatigue crack has three stages： rapid propagation,steady propagation and instability propagation.The interface crack propagation rate was described in the form of Paris formula before the instability propagation.SIF of the initial crack at mid-span interface reached the maximum and then decreased with the interface crack length.In elastic range of the reinforcing steel bar,the strengthened beam with prestress had large SIF compared with the strengthened beam without prestress.
出处
《工程力学》
EI
CSCD
北大核心
2011年第7期180-185,216,共7页
Engineering Mechanics
基金
国家自然科学基金项目(10672060
10802023)
广东省博士启动基金项目(10451009001004769)
广东省教育厅育苗工程项目(LYM10069)
