Experimental study on fatigue behavior of butt-welded thin-walled steel plates strengthened using CFRP sheets. (February 2020)

• Record Type: Journal Article
• Authors: Tong, Lewei; Yu, Qitong; Zhao, Xiao-Ling
• Is Part Of: Thin-walled structures. Volume 147(2020)
• Publication Date: 2020-02
• Subjects: Butt-welded steel plates -- Carbon fiber reinforced polymer (CFRP) -- Strengthening -- Fatigue test -- S–N curve; Thin-walled structures -- Periodicals; 690.1
• DOI: 10.1016/j.tws.2019.106471
• Languages: English
• ISSNs: 0263-8231

Abstract

Abstract: Welded steel joints in structures are susceptible to fatigue failure. In this context, advanced carbon fiber reinforced polymer (CFRP) possess a demonstrated potential for the fatigue strengthening of steel structures. However, limited information is available on CFRP strengthening of butt-welded joints, which are the most common joint types in steel structures. This paper presents a study on fatigue behavior of butt-welded thin-walled steel plates strengthened using CFRP sheets. A total of 34 specimens with both single-sided and double-sided strengthening were performed via constant amplitude tensile fatigue loading, and another four specimens were employed for hot-spot stress measurement. The effect of CFRP strengthening on fatigue behavior was investigated by varying the strengthening scheme (single-sided or double-sided) and the number of CFRP sheet layers. Test results showed that the fatigue life of butt-welded steel plates with CFRP strengthening increased by approximately one to ten times when compared to the fatigue life of butt-welded steel plates without CFRP strengthening. Triple-layered double-sided specimens seemed to exhibit the best effect on fatigue life; their fatigue strength at 2 million cycles increased by 34% compared to that of specimens without CFRP strengthening. Specific fatigue design S–N curves of butt-welded thin-walled steel plates with and without CFRP strengthening were proposed directly. The fatigue test results were used to calibrate a fatigue design approach for CFRP strengthened butt-welded steel plates. In addition, the effect of CFRP strengthening on stiffness degradation was also discussed. Highlights: Thirty-four fatigue tests on CFRP strengthened butt-welded thin steel plates were conducted. Stress concentration factors for CFRP strengthened butt-welded steel plates were measured. Fatigue design approach for CFRP strengthened butt-welded steel plates was calibrated. The effect of CFRP strengthening on stiffness degradation was discussed.