Experimental investigation of the behavior of joints by glued- in steel and glass fiber reinforced plastic rods parallel to poplar wood grain

Nowadays, using of fiber reinforced plastic (FRP) rods in composites structures has been increased due to their light weight and high specific strength. In this research, the behavior of steel and glass-FRP rods with different surface patterns (plain, ribbed) were experimentally investigated in the points of bonding length (200, 300 mm) and adhesive type (unsaturated polyester, epoxy) view, parallel to poplar (Populus alba) wood grain. In this regards, after specimens preparation based on the above mentioned situations, tensile pull-out strength, shear stress, as well as failure modes in wood-adhesive and rod-adhesive interfaces were investigated. The maximum value for poll-out strength, i.e. 82.5 kN was achieved for ribbed glass-FRP rods, and 300 mm anchorage length. In addition, while pull-out load carrying capacity increased with increasing bonding length, nominal shear stresses were decreased from 6.8 to 3.8 MPa, and 8.9 to 4.7 MPa, respectively for wood-adhesive, and rod-adhesive interfaces. Worth noting, the most common failure mode was pull-out of rods with attached wood, due to shear failure parallel to the wood grains.