Wu Jingyu, Zhu Yongquan, Li Chenggao
College of Civil Engineering, Shandong Jianzhu University, Jinan 250101, China.
Key Laboratory of Building Structural Retrofitting and Underground Space Engineering, Shandong Jianzhu University, Ministry of Education, Jinan 250101, China.
Polymers (Basel). 2023 May 27;15(11):2483. doi: 10.3390/polym15112483.
In this study, the variation of fatigue stiffness, fatigue life, and residual strength, as well as the macroscopic damage initiation, expansion, and fracture of CFRP (carbon fiber reinforced polymer) rods in bending-anchored CFRP cable, were investigated experimentally to verify the anchoring performance of the bending anchoring system and evaluate the additional shear effect caused by bending anchoring. Additionally, the acoustic emission technique was used to monitor the progression of critical microscopic damage to CFRP rods in a bending anchoring system, which is closely related to the compression-shear fracture of CFRP rods within the anchor. The experimental results indicate that after the fatigue cycles of two million, the residual strength retention rate of CFRP rod was as high as 95.1% and 76.7% under the stress amplitudes of 500 MPa and 600 MPa, indicating good fatigue resistance. Moreover, the bending-anchored CFRP cable could withstand 2 million cycles of fatigue loading with a maximum stress of 0.4 and an amplitude of 500 MPa without obvious fatigue damage. Moreover, under more severe fatigue-loading conditions, it can be found that fiber splitting in CFRP rods in the free section of cable and compression-shear fracture of CFRP rods are the predominant macroscopic damage modes, and the spatial distribution of macroscopic fatigue damage of CFRP rods reveals that the additional shear effect has become the determining factor in the fatigue resistance of the cable. This study demonstrates the good fatigue-bearing capacity of CFRP cable with a bending anchoring system, and the findings can be used for the optimization of the bending anchoring system to further enhance its fatigue resistance, which further promotes the application and development of CFRP cable and bending anchoring system in bridge structures.
在本研究中，对弯曲锚固碳纤维增强聚合物（CFRP）拉索中CFRP杆的疲劳刚度、疲劳寿命和残余强度的变化，以及宏观损伤的起始、扩展和断裂进行了实验研究，以验证弯曲锚固系统的锚固性能，并评估弯曲锚固引起的附加剪切效应。此外，采用声发射技术监测弯曲锚固系统中CFRP杆临界微观损伤的发展过程，这与锚固区内CFRP杆的压剪断裂密切相关。实验结果表明，在两百万次疲劳循环后，CFRP杆在500MPa和600MPa应力幅值下的残余强度保留率分别高达95.1%和76.7%，表明其具有良好的抗疲劳性能。此外，弯曲锚固CFRP拉索在最大应力为0.4、幅值为500MPa的情况下，能够承受两百万次疲劳加载而无明显疲劳损伤。此外，在更严酷的疲劳加载条件下，可以发现拉索自由段CFRP杆中的纤维劈裂和CFRP杆的压剪断裂是主要的宏观损伤模式，CFRP杆宏观疲劳损伤的空间分布表明附加剪切效应已成为拉索抗疲劳性能的决定性因素。本研究证明了弯曲锚固系统CFRP拉索具有良好的疲劳承载能力，研究结果可用于弯曲锚固系统的优化，以进一步提高其抗疲劳性能，从而进一步推动CFRP拉索和弯曲锚固系统在桥梁结构中的应用与发展。
