Low-grade glued laminated timber reinforced with FRP plate

Abstract

Fibre-reinforced polymers (FRPs) are an accepted material by structural engineers for the strengthening of structural elements. With increasing environmental concerns, further emphasis is being placed on the use of sustainable construction materials such as timber. This paper describes an experimental programme which examines the reinforcement in flexure of low-grade glued laminated timber (glulam) with a commercially attractive recyclable FRP. Unreinforced glulam beams, FRP plate reinforced glulam beams, unreinforced glulam beams incorporating an additional sacrificial lamination and FRP plate reinforced glulam beams, which had a sacrificial lamination bonded beneath the FRP plate, were fabricated and tested in flexure. The unreinforced glulam demonstrated linear elastic behaviour and exhibited brittle tensile-flexural failures in comparison to the pseudo-ductile behaviour of the reinforced beams. The addition of reasonable reinforcement percentages strategically located in the tension zone resulted in moderate enhancements in the stiffness while more significant improvements in the ultimate moment capacity were obtained. Strain profiles illustrated that increased utilisation of the compression strength of the timber is obtained when FRP reinforcement is included.