Flexural strengthening of finger-jointed Spruce timber beams with CFRP

Abstract

This study describes an experimental and numerical investigation of the use of CFRP material for strengthening finger-jointed Spruce timber beams. The corresponding experimental work was based on a four-point bending test configuration in order to characterise stiffness, ductility and strength. The results show that the external bonding of CFRP increased the ultimate load-bearing capacity of finger-jointed Spruce timber beams under flexure. FE simulations were also carried out, based on the cohesive zone model (CZM) available in Abaqus software to allow an accurate description of the damage evolution of the bond lines within the finger joint until failure. The FE models incorporated the different materials’ nonlinear constitutive laws including bond-slip action between finger joints and CFRP–timber interface. The results indicated increases of 33.84% and 16.7% for flexural capacity and initial stiffness, respectively, in comparison with unreinforced finger-jointed Spruce specimens. Besides, comparisons of computed and experimental ultimate loads for all tested specimens showed that the absolute error was around 5%. It is concluded that the developed FE models are able to predict accurately ultimate load and failure mode of finger-jointed Spruce timber beams strengthened with CFRP materials.