Abstract
Using carbon fiber reinforced polymer (CFRP) composites for enhancing the fatigue behavior of the steel structures will be an important application. As the most critical part, the fatigue behavior of the CFRP-to-steel bonded interface directly determines the strengthening effect of steel structures reinforced by CFRP. In this paper, a series of CFRP-to-steel double-shear specimens are performed in order to study the interfacial bond behavior between CFRP and steel under fatigue loading. Two parameters are considered: the upper bound value and the lower bound value of the fatigue loading. An analysis of test results indicates that the crack development rate increases with the increment of the stress ratio or stress level and the crack development process includes two phases: crack stable development phase and debonding failure phase. A calculation model is put forward to describe the relationship between the crack development rate and the stress level. Besides, it can be obtained from the test results that the fatigue lives of the specimens decrease with the increment of the stress level. The empirical formula of S-N curve based on the form of single logarithm formula is proposed and the fatigue limit under the experimental conditions in this paper is determined to be 0.343 by computational analysis.
Highlights
There are masses of defective steel structures that cannot meet the requirement of the design and operational caused by construction defects, environmental corrosion, and long-term cyclic loading
The failure occurred suddenly with a loud noise when the debonding extended to the end of the carbon fiber reinforced polymer (CFRP) sheets near the loaded end
Experimental and theoretical research was conducted in order to investigate the bond behavior of the interface between CFRP sheets and steel plates
Summary
There are masses of defective steel structures that cannot meet the requirement of the design and operational caused by construction defects, environmental corrosion, and long-term cyclic loading. These defective steel structures urgently need to be strengthened and repaired. Current studies about the bond behavior of CFRP-to-steel bonded interfaces under static loading have been carried out [12,13,14,15,16,17]. It is highly necessary to conduct thorough research on the fatigue performance of the bonded interfaces between CFRP and steel under cyclic loading
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