芳纶纤维加固钢筋混凝土梁锚固长度的简化计算方法

SIMPLIFIED CALCULATING METHOD OF AFRP BONDING LENGTH FOR REINFORCED CONCRETE BEAMS STRENGTHENED WITH EXTERNALLY BONDED AFRP

根据芳纶纤维(Aramid Fiber Reinforced Plastic,简称AFRP)补强加固钢筋混凝土梁的粘结破坏的试验结果,分析AFRP加固钢筋混凝土抗弯构件粘结界面的剪应力的分布规律,即在纤维截断点处存在较高的应力集中,随着离截断点距离的增大剪应力分布逐渐趋于均匀。粘结锚固长度不足和过高的应力集中是造成AFRP加固钢筋混凝土构件早期破坏的主要原因。采用"齿"状块体力学计算模型和混凝土裂缝理论推导了AFRP加固钢筋混凝土梁所需要的有效锚固长度,并通过修正得出了AFRP加固钢筋混凝土受弯构件最小锚固长度的简化计算公式,提出了AFRP的容许应变值和避免AFRP早期破坏应采用的措施,可供AFRP加固工程设计和施工参考。

Based on the test results of RC beam strengthened with externally bonded AFRP, this paper analyzes the premature failure process of reinforced concrete members strengthened with externally bonded AFRP, the interfacial shear stress is maximum at the AFRP cut-off point and starts to decay as the distance from the cut-off point is increased, the insufficiency and the high interfacial shear stress concentration in the plate containment region are the main causes leading to the failure of reinforced concrete members strengthened with externally bonded AFRP. This paper also analyzes the effective anchorage length of AFRP with the mechanics model of tooth block and crack theory of concrete, works out the calculating formula of least anchorage length of AFRP for strengthening reinforced concrete beam with further simplified correction, and finally puts forward the tolerance strain value of FRP and the measures taken to avoid the premature failure of FRP, which provide theory basis for design and construction of strengthening with externally bonded FRP.