Fatigue Behavior of Cracked High-Strength Steel Plates Strengthened by CFRP Sheets
Fatigue Behavior of Cracked High-Strength Steel Plates Strengthened by CFRP Sheets
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DOI：
10.1061/(asce)cc.1943-5614.0000698
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发表时间：
2016-12-01
影响因子：
4.6
通讯作者：
Feng, Peng
中科院分区：
文献类型：
--
作者：
Hu, Li Li;Zhao, Xiao Ling;Feng, Peng
高强度钢广泛应用于建筑、桥梁、铁路和其他结构中。然而，对于碳纤维增强聚合物(CFRP)片材开裂的高强度钢板，已经进行了有限的疲劳试验。本文研究了Q345、Q460和Q690钢板未强化和碳纤维布加固后的疲劳性能。首先，分析了这些钢的力学性能与化学成分和金相组织的关系。发现微合金化可以细化晶粒度，从而提高强度。其次，进行了10块裸钢板和9块加固钢板在不同应力范围和不同应力水平(最大应力与屈服应力之比)下的疲劳试验。结果表明，对于未强化试件，Q690在175.5 Mpa应力范围内的疲劳性能最好，Q460次之，Q345次之。然而，在相同应力水平下，Q690的疲劳寿命最短，其次是Q460，然后是Q345。对于强化后的试件，观察到了不同的破坏模式，在402.5 Mpa的应力范围内，Q690钢发生了严重的脱粘。CFRP加固技术可有效提高除Q690试件外的所有试件的疲劳寿命(1.3~3.1倍)。用扫描电子显微镜(SEM)观察了断口的微观结构。最后，对三种钢的断裂力学理论中的材料相关常数进行了拟合，并利用巴黎定律对疲劳寿命进行了准确的预测。(C)2016年美国土木工程师学会。
High strength steel is widely used in buildings, bridges, railways, and other structures. However, limited fatigue experiments have been conducted for cracked high strength steel plates with carbon fiber-reinforced polymer (CFRP) sheets. This paper describes an investigation into the fatigue behavior of unstrengthened and CFRP strengthened cracked Q345, Q460, and Q690 steel plates. First, the mechanical properties of these steels, which are dependent on the chemical composition and metallographic structure, were analyzed. Microalloying was found to refine the grain size and thereby enhance the strength. Second, 10 bare steel plates and nine strengthened steel plates were tested under fatigue loading at different stress ranges and stress levels (defined as the ratio of the maximum stress to the yield stress). For the unstrengthened specimens, the results show that the fatigue behavior at a 175.5 MPa stress range is best for Q690, followed by Q460 and then Q345. However, at the same stress level, the fatigue life of Q690 was shortest, followed by Q460 and then Q345. For the strengthened specimens, different failure modes were observed, and serious debonding occurred in Q690 steel under a 402.5 MPa stress range. CFRP strengthening technology can effectively increase the fatigue life (1.3-3.1 times) for all specimens except the Q690 specimen. The microstructure of the fracture surface was then investigated by scanning electron microscopy (SEM). Finally, a fit of material-related constants in fracture mechanics theory was obtained for the three categories of steel, and the fatigue life was predicted accurately using Paris' law. (C) 2016 American Society of Civil Engineers.