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.

为了分析钢筋混凝土结构的变形行为，有必要了解钢筋与混凝土之间的相互作用。相互作用通常由棒材的局部粘结应力-局部滑移关系来表示。一些局部债券应力滑移模型已经提出。然而，这些模型大多数是通过静态试验获得的，并不总是适用于承受恒载或持续载荷的结构分析。本研究的目的是阐明持续荷载下时间流逝对粘结行为的影响，并提出一种与时间相关的粘结模型。混凝土与钢筋的粘结机制是力库前面的混凝土抵抗钢筋库。在这种情况下，三轴下的极高应力会导致库前部的混凝土受到影响。因此，有必要找出三轴高应力条件下混凝土的徐变特性，以建立精确的粘结徐变模型。对大型混凝土块中埋入钢筋进行持续荷载作用下的轴向拉拔试验，以测量加载后沿埋入钢筋的应变分布随时间的变化。讨论了加载后时间对局部粘结应力-滑移关系的影响。研究发现，在局部滑移较大的地方，埋入混凝土砌块中的钢筋应变随时间增加而增大，粘结应力随时间显着减小。