Experimental study on the behavior of GFRP-to-steel bolted joints

Experimental research has been conducted to study the behavior of a new type of GFRP-to-steel bolted joint. Two types of GFRP-to-steel bolted joints were investigated in this paper including ordinary GFRP-to-steel bolted joint (specimen JO) which only use bolts and washers and stiffer GFRP-to-steel bolted joint (specimen JS) reinforced with epoxy and steel cover plates. The observed failure modes of the two types of connections were always the failure of the pultruded GFRP profiles. The data of applied load and displacement of representative specimens were obtained during the tests. Test results indicated that specimen JS exhibited an increase of 422% in the mean initial stiffness, 61.9% in the average joint strength and 12.6% in the mean joint efficiency, respectively, over specimen JO, therefore it can be stated that the behavior of specimen JS is superior to the performance of specimen JO. Meanwhile, it is also found that the performance of the interface between GFRP shape and cover plates is one of the key factors that affects the behavior of specimen JS due to the fact that the ultimate failure took place as soon as debonding occurred between GFRP element and cover plates. Furthermore, the influence of the slip factor on the slip load was also studied.