Effect of glue-line thickness on pull-out behavior of glued-in GFRP rods in LVL: Finite element analysis

This paper uses finite element analysis (FEA) to verify the results of previous experimental works conducted on the effect of glue-line thickness and rate of loading on pull-out behavior of glued-in GFRP rods in LVL. For this purpose, the materials were considered as orthotropic for the timber and the GFRP rod, and isotropic for epoxy resin. To determine the effects of thickness on pull-out, four glue-lines namely 0.5, 1, 2 and 4 mm were modelled. To examine the effects of rate of loading, three glue-lines 0.5, 2 and 4 mm were modelled with different values of modulus of elasticity selected for the resin to simulate higher and lower rates of loading. Results showed that with an increasing thickness of glue-line, the concentration of Z-direction stresses declines across the glue-line thickness from the rod-adhesive interface towards the adhesive-timber interface and the magnitude of shear stresses, τXZ, increases to a maximum within the glue-line in a zone about 20-30% into the resin layer and this is seen for all glue-line thicknesses. Also, by changing values of elastic modulus for the resin in the FE model to simulate rate of loading, it was shown that thicker glue-lines are more sensitive to loading rate.