Develpoment of time dependent bond model between steel bar and concrete

钢筋与混凝土间随时间变化的粘结模型的开发

• 批准号: 10650455
• 负责人: SHIMA Hiroshi
• 金额: $ 1.92万
• 依托单位: Kochi University of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10650455/
• 关键词: concrete; deformed bar; bond stress-slip; bond creep

For the analysis of deformational behaviors of reinforced concrete structures, it is necessary to know about interaction between steel bars and concrete. The interaction is generally represented by a local bond stress-local slip relationship of the bar. Some local bond stress-slip models have already proposed. However, most of these models were obtained from static tests and can not always be applied to the analysis of structures subjected tQ dead or sustained loads. The subject of this research is to clarify the effect of time passing on bond behavior under sustained load and to propose a time dependent bond model.Mechanism of bond of concrete to steel bar is that concrete in the front of the lib resists against the bar lib. Extremely high stress under three axes causes on the concrete in the front of the lib at this condition. Therefore, it is necessary to find the creep characteristic of concrete under three axes high stress conditions in order to develop a precise bond creep model. Axial pullout test of bar embedded in large concrete block under a sustained load was carried out in order to measure the change of strain distribution along embedded bar with time after loading. The effect of time after loading on the local bond stress-slip relationship was discussed. It was found that the strains of steel bar embedded in concrete block increased wIth time and the bond stress decreased with time remarkably where the local slip was larger.

在分析钢筋混凝土结构的变形性能时，必须了解钢筋与混凝土的相互作用。这种相互作用通常表现为杆的局部粘结-局部滑移关系。已经提出了一些局部粘结应力-滑移模型。然而，这些模型大多是从静力试验中获得的，并不总是适用于结构承受tQ恒载或持续荷载的分析。本研究的主题是阐明时间传递对持续载荷下键行为的影响，并提出一个时间依赖的键模型。混凝土与钢筋的粘结机理是钢筋前部的混凝土对钢筋的抵抗作用。在这种情况下，三轴下的极高应力会对lib前部的混凝土产生影响。因此，有必要研究混凝土在三轴高应力条件下的徐变特性，以建立精确的粘结蠕变模型。为了测量加载后沿预埋杆应变分布随时间的变化，进行了大型混凝土砌块内预埋杆在持续荷载作用下的轴向拉拔试验。讨论了加载后时间对局部粘结应力-滑移关系的影响。结果表明，当局部滑移较大时，混凝土砌块内嵌钢筋的应变随时间增大，粘结应力随时间减小。