Bending reinforcement of cedar glulam beam with inserted GFRP and BFRP plates

This study investigates the bending performance enhancement of glued laminated timber (glulam) beams reinforced with glass fiber reinforced polymer (GFRP) and basalt fiber reinforced biopolymer (BFRP) containing biomass material in its matrix resin. The glulam beams were reinforced with inserted GFRP and BFRP plates. At first, a four-point bending experiment was conducted, which demonstrated that the bending modulus and strength increased by the reinforcement. The strain distribution across the height of the beam was nearly linear, and the bonding between glulam and FRP did not fail until the maximum load. The failure mode of the reinforced beams was dominated by tensile fracture of the glulam beam. The observed ultimate bending strain was close to the tensile fracture strain derived from material test. Additionally, this study proposed a theoretical model to calculate the bending strength of the reinforced glulam beam. This model accounted for strain variation in the FRP plate. The proposed model demonstrated better agreement with the test values.