[关键词]
[摘要]
目前有关带肋纤维增强复合材料(FRP)筋粘结性能的研究不足。收集粘结纤维肋FRP筋(简称粘结肋FRP筋)和机械刻槽肋FRP筋(简称刻槽肋FRP筋)的试验数据,探究各参数对粘结性能的影响。结果表明:两种带肋FRP筋的宏观破坏模式都是拔出破坏,在细观上粘结肋FRP筋主要为FRP筋肋的剪切剥落,而混凝土损伤较轻微,大部分刻槽肋FRP筋表现为混凝土肋剪切破坏,二者的粘结强度随混凝土强度的增加而增大;增加保护层厚度可增强混凝土对FRP筋的约束效果,有助于提高粘结肋FRP筋的粘结强度,但对刻槽肋FRP筋几乎没有影响;增加相对肋高hrd和FRP筋肋宽比FR可提高粘结肋FRP筋的粘结强度;而刻槽肋FRP筋几乎不受hrd的影响,主要受混凝土肋宽比CR的影响,其粘结强度随CR的增加而增大;建立的粘结强度公式计算值与试验结果吻合较好,预测精度高于设计规范,主要原因在于该公式准确考虑了FRP筋肋成型工艺和几何特征对粘结强度的影响。
[Key word]
[Abstract]
Until now, there has been limited research on the bonding behavior of ribbed fiber-reinforced polymer (FRP) bars. In this paper, bond test data of the spirally-glued FRP bar and mechanically-grooved FRP bar were collected to investigate the test parameters on the bond behavior. The results show that the macroscopic failure mode for the two types of ribbed FRP bars is pullout failure. More specifically, spirally-glued FRP bars mainly exhibit shearing off of FRP bar ribs, while slight damage occurs in concrete. Most grooved FRP bars show shearing off of concrete ribs, and the bond strength increases with the increase of concrete strength for both FRP bars. Spirally-glued FRP bars show higher bond strength by increasing concrete cover which contributes to better confinement to FRP bars, but this seems to have no effect on grooved FRP bars. The bond strength of spirally-glued FRP bars can be improved by increasing relative rib height hrd and FRP bar rib width ratio FR. While grooved FRP bars are almost unaffected by hrd, and are mainly influenced by concrete rib width ratio CR, having higher bond strength by increasing CR. The calculated results by the proposed equations are in good agreement with the test results with greater accuracy than the design codes. This is because the effect of rib forming process and geometrical features of ribbed FRP bars on bond strength is accurately accounted in the proposed equations.
[中图分类号]
TU511.3
[基金项目]
国家自然科学基金(51878224)