复材网格-UHTCC复合增强钢筋混凝土梁抗弯性能试验研究

Experimental research on flexural behavior of RC beams strengthened with FRP grid-UHTCC composite

文中进行7根复材(FRP)网格增强超高韧性纤维水泥基(UHTCC)复合加固钢筋混凝土梁的抗弯性能试验,将FRP网格类型、FRP网格增强率、FRP-UHTCC复合层黏结长度作为试验变量,分析各变量对FRP-UHTCC复合增强混凝土梁弯曲性能的影响。在试验研究的基础上,给出FRP-UHTCC复合增强混凝土梁的抗弯承载力计算方法。试验结果表明,FRP-UHTCC复合层与混凝土间没有发生相对滑移现象,可以有效抑制加固层端部剥离破坏,加固梁的破坏模式为FRP网格中纵向纤维筋被拉断破坏。BFRP格栅与UHTCC黏结基体没有发生脱黏现象,优于BFRP编织网与UHTCC的黏结效果。随着FRP网格增强率的增大,加固梁的抗弯承载力得到显著提高。与未加固的普通混凝土梁相比,加固梁的开裂、屈服和极限荷载最大提高幅度分别为97%、35%和33%。计算结果表明,预测值与试验值吻合较好,可以有效地预测FRP-UHTCC复合增强混凝土梁的抗弯承载力。

Experiments on seven reinforced concrete （RC） beams strengthened with FRP grid reinforced Ultra High Toughness Cementitious Composite （UHTCC） were conducted to investigate their flexural performance. The types of FRP grid, the reinforcement ratios of FRP grid and the bonding length of the FRP-UHTCC composite layer were selected as the test parameters and the effects of the parameters on the flexural behaviour of RC beams strengthened with FRP- UHTCC were investigated. Based on the test results, the calculation method for the flexural capacity of those strengthened RC beams was proposed. The experimental results showed that there was no relative slip between the FRP- UHTCC composite layer and concrete matrix, so that the debonding failure at the end of reinforced composite layer could be effectively suppressed. The failure mode of the strengthened RC beam was the tensile rupture of partial longitudinal fiber reinforcement in the BFRP grid. The debonding phenomenon between the BFRP grid and UHTCC matrix was not observed, indicating that the bonding is better than that between BFRP textile and UHTCC matrix. The flexural capacity of strengthened RC beam was greatly improved with the increase of reinforcement ratio of BFRP grid. Compared with the RC beam without strengthening, the maximum increases in the cracking, yielding and ultimate limit load of the strengthened beams were 97%, 35% and 33%, respectively. The calculation results showed that the predicted values had good agreements with the test data, implying that the flexural capacity of RC beam strengthened with FRP-UHTCC composite can be effectively predicted.