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Study on Flexural Behavior of High-Strength Reinforced Concrete Columns Confined by Steel Tube

钢管约束高强钢筋混凝土柱弯曲性能研究

基本信息

批准号：
11650588
负责人：
SUN Yuping
金额：
$ 1.86万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650588/
关键词：
Square steel tube Confined concrete High-strength concrete Width-to-thickness ration Axial load ratio Ultimate moment Ultimate curvature Ultimate strain

项目摘要

An experimental study of monotonic flexural behavior of reinforced concrete columns confined by square or circular steel tube was conducted to investigate effects of lateral confinement by steel tubes on ultimate flexural properties of the confined high-strength reinforced concrete columns. Twenty test columns, ten of which were confined by square steel tubes and the others by circular steel tubes, were made of high-strength concrete with compressive strength of 60MPa or 100MPa, and all of these columns were tested under combined monotonic bending moment and constant axial compression. Test results indicated that flexural response as well as ultimate properties of a confined high-strength concrete column not only depended upon wall thickness of the steel tube, but the axial load level as well. It has also been shown that confinement effect of circular steel tube was much higher than that of square steel tube when the steel tubes had the same wall thickness. The most interesting experim … More ental result obtained in this study was that the compressive strain at the extreme concrete fiber of the confined concrete section developed at the maximum moment was not a constant as recommended in many current design codes, but a variant increasing as the confinement degree provided by the steel tubes almost regardless of the axial load level.Parallel to the experimental study described above, an analytical study of the flexural response of confined high-strength reinforced concrete columns was carried on to develop a simple and practical method of theoretically evaluating the ultimate moment and deformation capacity of confined concrete column. Based on the results of parametric study, a mathematical expression for predicting the ultimate strain of confined concrete was developed. Furthermore, two rectangular equivalent stress blocks were proposed to simplify the calculation of ultimate moment capacity. One stress block was proposed for columns confined by square steel tube and the other was for columns confined by circular steel tubes. Good agreement between the measured results and the theoretical predictions verified validity of the proposed stress blocks. Less

通过方钢管和圆钢管约束钢筋混凝土柱单调受弯试验，研究了钢管侧向约束对约束高强钢筋混凝土柱极限受弯性能的影响。采用高强混凝土（抗压强度为60 MPa和100 MPa）制作20根试验柱，其中10根为方钢管约束柱，另10根为圆钢管约束柱，进行了单调弯矩和恒定轴压联合作用试验。试验结果表明，约束高强混凝土柱的受弯响应和极限承载力不仅与钢管壁厚有关，还与轴压水平有关。当钢管壁厚相同时，圆钢管的约束效应远大于方钢管。最有趣的体验 ...更多信息研究结果表明，在最大弯矩作用下，约束混凝土截面的极限混凝土纤维处的压应变并不是现行设计规范中所推荐的常数，而是随着钢管约束程度的增加而增加的一个变量，与轴向荷载水平几乎无关。摘要对约束高强钢筋混凝土柱的受弯性能进行了分析研究，提出了一种简单实用的计算约束高强钢筋混凝土柱极限弯矩和变形能力的方法。基于参数研究的结果，提出了约束混凝土极限应变的数学表达式。此外，提出了两个矩形等效应力块，简化了极限抗弯承载力的计算。提出了一种方钢管约束柱和一种圆钢管约束柱的应力块。实测结果与理论预测吻合较好，验证了所提出应力块的有效性。少