Research On Bending Mechanical Properties Of Structural Glulam Beam Strengthened By FRP

Fiber reinforced polymer combined with structural Glulam beam could provide substancial improvements in bending mechanical properties effectively. What appears of most significance in developing such a composite beam is gluability between FRP and Glulam laminations. Reinforcements should be placed in suitable configurations to more efficiently improve the overall bending mechanical properties of composite Glulam beams. The bending failure modes of structural Glulam beam strengthened by FRP are influenced by a multiplicity of different factors such as dimension specifications, material performance characters and the mechanical property differences between FRP and wood etc. Thus we should establish the bending mechanics model of composite beam so as to analyse and inspect composite beam in a simple and rapid way. Specific studies are as follows:Scots pine and spruce Glulam were prepared and producted in accordance with technology and parameters presented by Purbond polyurethane adhesive manufacturer. Bonding properties of Glulam samples was evaluated adhering to concerned delamination and shear requirements. The test results are as follows:All test samples could be applied in environment of service class 3. Spruce samples could be bonded more easily in contrast to Scots pine.Through comparative study of plasma and hydroxymethyl resorcinol on basis of bonding interface modification we have obtained tentative optimized interface treatment technology:FRP didn’t accept any surface treatment. Whereas wood was treated by plasma at the speed of 2.5m/min and 400 watts for 5 times before coating hydroxymethyl resorcinol to the amount of 150g/m2. Each processing procedure is similar with bamboo lamination except for feeding speed of 1.25m/min. All evaluation indices of bonding properties meet the requirements of service class 3 prescribed in GB/T26899-2011.By analyzing the influences of different configurations of FRP associated with bamboo plate in structural Glulam beam on the bending mechanical behaviors of composite beam, we could draw some conclusions as follows:The bending failure of all Glulam beams were initiated by compressive yielding of the outermost laminations situated in compressive zone. Comparing to K-B control group, the bending strength of Z-B and S-B groups were increased by 10.37% and 26.96% respectively. P-B group could reduce the use of FRP plate by 33.3% in contrast to B-B group. As for the Glulam beam excessively strengthened by FRP, Placing reinforcement in compressive zone could attain further improvement in bending mechanical performance.Programmed by C language, the bending stiffness model of Glulam beam was initially established on basis of parallel axis theorem in accordance with transformed section method. Moreover, seven full-scale structural Glulam beams were conducted bending mechanical experiment to verify the validity of model. The test results were demonstrated as follows:The executive C programme model could accurately predict the bending stiffness of structural Glulam beam.Comparing the theoretical value elicited by C programme model with experimental values of structural Glulam beams, the relative error rate is 3.89 percent.Compiled by C language, the ultimate bending moment model of structural Glulam beam strengthened by FRP was originally established adhering to the equation of static equilibrium of bending normal stress of mid-span cross section. In addition, the full-scale bending experiment of 9 Composite Glulam beams demonstrated that the model could predict the ultimate bending moment of composite Glulam beam with relative accuracy. Four of them had the relative error rate within 5 percent, while other four beams not in excess of 11 percent.