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Bond Splitting Strength in Reinforced Concrete Members

钢筋混凝土构件中的粘结劈裂强度

基本信息

批准号：
04402042
负责人：
OTANI Shunsuke
金额：
$ 9.09万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (A)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1995
项目状态：
已结题

项目摘要

Eight full-scale simply supported beams, four half-scale beams under load reversals, and four columns were tested in 1992,1993, and 1994, respectively, to gather experimental data about the effect of confinement stress on bond behavior in longitudinal bars. The specimens were designed to fail in bond splitting along the longitudinal bars. The variables of specimens were the number and the diameter of test bars, the spacing of lateral reinforcement, the use of sub ties, and axial stress ratio. From the test results, maximum bond stress was observed to improve as the amount of lateral reinforcement increases, and the effectiveness of sub-ties, which confine intermediate bars, was observed. Bond stress was observed to be governed by the confinement stress provided by lateral reinforcement. To evaluate the confinement stresses acting on the splitting plane, an analytical study was carried out in 1995. A simple analytical model consisted of three components : (1) beam which represents cover concrete ; (2) steel columns connected to the beam with pin connection, which represents hoops and sub-ties ; (3) crack spring which represent tensile force and crack opening of concrete in the splitting plane. From the analystical study of the confinement stresses provided by cover concrete, hoops and sub-ties, the concrete between bars does not contribute to the confinement at ultimate state. Analytically predicted ultimate bond stress agreed with the test results.

分别于 1992 年、1993 年和 1994 年对八根全尺寸简支梁、四根半尺寸梁和四根柱进行了荷载反转试验，以收集有关约束应力对纵向钢筋粘结行为影响的实验数据。样本被设计成不能沿着纵向钢筋发生粘结分裂。样本的变量是测试钢筋的数量和直径、侧向钢筋的间距、子拉杆的使用以及轴应力比。从测试结果来看，随着侧向钢筋数量的增加，观察到最大粘结应力有所改善，并且观察到限制中间钢筋的子拉杆的有效性。据观察，粘结应力受侧向钢筋提供的限制应力的控制。为了评估作用在劈裂面上的约束应力，1995年进行了分析研究。一个简单的分析模型由三个部分组成：（1）代表覆盖混凝土的梁； (2)钢柱与梁采用销钉连接，代表箍筋和子拉杆； (3)裂缝弹簧，代表混凝土在劈裂面上的拉力和裂缝张开程度。根据对保护层混凝土、箍筋和子拉杆提供的约束应力的分析研究，钢筋之间的混凝土对最终状态下的约束没有贡献。分析预测的最终粘合应力与测试结果一致。