Enhancing Fatigue Performance of Steel Structures using Carbon Fibre Reinforced Composites

In this experimental research the effect of CFRP patches on the fatiguelife of notched steel plates has been investigated. This research has beenperformed for two main reasons: ١.the popularity of composites in therehabilitation and repair industry and ٢: the significance of repairingcracked ageing steel structures reaching their designed fatigue life.In this research two main aspects are studied. The first is the effect ofCFRP (passive effect) on its own. The second is the active effect, in whicha pretension force is applied to the CFRP patch and then bondedperpendicular to the crack. Two types of CFRP patches are used: normalmodulus sheets and ultra-high modulus laminates. The former were used torepair ٦mm steel plates with application of prestress and the latter wereused to repair ١٠mm plates without prestress. In order to achievecomparable results despite using different materials, the experiments werecarried out under fatigue loads that produced the same amount of stress onthe bare steel plates. Crack propagation versus number of cycles was themain output of the experiments, determined using the beach markingtechnique.

Keywords:

CFRP , Fatigue , Steel , Crack propagation , Repair , Prestress