自锁碳纤维布间接加固混凝土框架中节点的抗震性能

Seismic behaviors of internal RC frame joints indirectly strengthened with self-locked CFRP sheets

通过5个加固节点试件的低周反复荷载模型试验,对自锁CFRP布间接加固混凝土框架中节点的破坏过程、承载能力、滞回曲线、延性以及耗能能力进行研究。基于混凝土结构抗震加固理论,考虑原节点核心区实际抗剪能力的修正以及梁柱端间接加固CFRP布对节点核心区抗剪能力的贡献,建立梁柱端自锁CFRP布抗震加固混凝土框架节点承载力的计算公式。研究结果表明:梁柱端自锁CFRP布间接加固技术能有效延缓纵筋在核心区的黏结滑移,避免CFRP被提前剥离破坏,明显改善节点的抗震性能,其承载能力、延性和耗能能力的提高幅度分别达到9.2%~21.6%,46.9%~61.8%和86.0%~125.0%;与增大梁柱端横向CFRP布箍配置率相比,适当增大梁端钢箍配置率或梁端纵向CFRP条带配置率对节点抗震性能的提高效果更显著;采用承载力计算公式所得计算值与试验值较吻合,该计算公式可用于实际工程中混凝土空间节点的CFRP抗震加固设计。

Five internal reinforced concrete （RC） frame joints were manufactured, and the failure process, bearing capacity, hysteresis curves, ductility and energy dissipation capacity of the joints indirectly strengthened with self-locked CFRP sheets were investigated under low cyclic loads. In consideration of the modification of actual shear capacity of the RC core area and the contribution of self-locked CFRP sheets at the beam and column ends, the formulas were derived for the bearing capacity of the indirectly CFRP-strengthening joints based on the theory of seismic strengthening of concrete structure. The results show that the self-locked CFRP sheets can delay the bond slip of longitudinal steel bars in the core area and prevent the premature debonding of the sheets effectively, and the improvement of bearing capacity, ductility coefficient and energy dissipation capacity of joints reaches 9.2%-21.6%, 46.9%-61.8% and 86.0%-125.0%respectively, and so the seismic behaviors of the joints are improved greatly. In addition, Reasonably increasing the amount of steel stirrups or longitudinal CFRP sheets at the beam end has more improved effects on the seismic behaviors than that of the lateral shear CFRP sheets. The predicted results agree well with the experimental values, which provide a reference for spatial joints strengthening with CFRP in practical engineering.