Experimental and Numerical Study on Strengthening of Steel Members Subjected to Impact Loading Using Ultrahigh Modulus CFRP

Carbon fiber-reinforced polymers (CFRPs) are commonly used for strengthening steel and concrete structures, with different types of CFRP used for strengthening different structural elements. A number of studies have focused on strengthening of steel members using low and normal-modulus CFRP. However, there is a lack of understanding on the use of ultrahigh modulus (UHM) CFRP for strengthening steel structures under impact loading. This paper presents experimental and numerical investigations on the effect of high load rates on the ultimate joint capacity, failure mode, effective bond length, and strain distribution along the bond interface between CFRP and steel plates in double-strap joints. Two methods of capturing strain were used in this program: (1) Image correlation photogrammetry was used for specimens tested under quasi-static tensile load, and (2) foil strain gauges were used for specimens tested under impact tensile loading. UHM CFRP was used to strengthen the joints using epoxy. The results show a significant increase in bond strength, and different failure modes were observed.