Fatigue behavior of notched steel beams strengthened by a prestressed CFRP plate subjected to wetting/drying cycles
Fatigue behavior of notched steel beams strengthened by a prestressed CFRP plate subjected to wetting/drying cycles
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预应力 CFRP 板加固的缺口钢梁在湿/干循环下的疲劳行为
DOI：
10.1016/j.compositesb.2021.109491
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发表时间：
2021-11-22
影响因子：
13.1
通讯作者：
Zhu, Miaochang
中科院分区：
文献类型：
--
作者：
Deng, Jun;Li, Junhui;Zhu, Miaochang
预应力碳纤维布（CFRP）加固对抑制钢梁裂缝扩展是有效的。然而，在湿热环境下的预应力CFRP缺口钢梁的疲劳性能还没有完全了解。通常，在钢梁上加工切口是模拟疲劳缺陷用于实验室试验的常用方法。在这项研究中，界面能量释放率在缺口位置首次推导出加固钢梁。理论分析结果表明，预应力CFRP加固能显著降低界面能量释放率，有助于改善界面疲劳性能。此外，缺口钢梁加固预应力CFRP（与预应力水平的CFRP板的抗拉强度的25%）暴露于干湿循环（WDC），然后在疲劳荷载下进行测试。试验结果表明，预应力CFRP加固使试件的界面剥离起始和破坏的疲劳抗力分别提高了3.47倍和7.83倍，这与理论分析结果所揭示的趋势一致。相比之下，WDC暴露减少了34.6%和27.2%，分别界面剥离开始和失败的疲劳寿命。提出了一种基于缺口处最大界面主应力的S-N曲线来预测加固钢梁剥离疲劳寿命的趋势。此外，基于巴黎定律，对有无WDC暴露加固钢梁的界面剥离疲劳寿命进行了趋势预测。
Prestressed carbon fiber reinforced polymer (CFRP) strengthening is effective in suppressing crack propagation of steel beams. However, the fatigue behavior of notched steel beams with prestressed CFRP under a hygrothermal environment is not fully understood. Generally, notch machining on the steel beam is an ordinary method to simulate a fatigue defect for laboratory tests. In this study, the interfacial energy release rate at the notch location was first derived for strengthened steel beams. The theoretical results show that the interfacial energy release rate can be significantly reduced by prestressed CFRP strengthening, contributing to improving the interfacial fatigue performance. In addition, notched steel beams strengthened by prestressed CFRP (with a prestress level of 25% of tensile strength of CFRP plate) were exposed to wetting/drying cycles (WDCs) and then tested under fatigue loading. The experimental results show that prestressed CFRP strengthening increases the fatigue resistance of interfacial debonding initiation and failure 3.47 times and 7.83 times, respectively, which agrees with the tendency revealed by the theoretical results. In contrast, WDC exposure reduced the fatigue lives of interfacial debonding initiation and failure by 34.6% and 27.2%, respectively. An S-N curve based on the maximum principal interfacial stress at the notch location was proposed to predict the tendency of fatigue life of debonding initiation for strengthened steel beams. Moreover, the tendency prediction for fatigue life of interfacial debonding development for the strengthened steel beams with/without WDC exposure was developed based on Paris' law.