Gary M. Raftery

Qualification of Wood Adhesives for Structural Softwood Glulam with Large Juvenile Wood Content

Abstract This paper reports on an experimental study to assess the bond quality achieved when bonding softwood spruce containing large proportions of juvenile wood with a range of conventional wood laminating adhesives. Adhesives examined comprised two phenol resorcinol formaldehydes, a melamine urea formaldehyde, a polyurethane, an emulsion polymer isocyanate and a polyvinyl acetate. The notched block shear test was utilised in which both non-moisture cycled and moisture cycled specimens were tested. The grain orientation of the wood, was carefully studied in the bonding process. Results indicated that the integrity of the bond was highly dependent on the adhesive under examination. No significant difference was observed at the interface when bonding to juvenile wood or to mature wood . Furthermore, no distinct performance difference for both non-moisture cycled and moisture cycled specimens was recorded when bonding to tangential grained or radial grained wood.

Seismic Tests of Welded Moment Resisting Connections Made of Laser-Welded Stainless Steel Sections

Steel structures are well established as the preferred material for constructing seismic resisting systems in New Zealand and around the world. While the majority of steel framing is made of carbon steel, stainless steel is increasingly being considered for designing exposed steel structures. Because of significant differences in the mechanical properties between the two materials, seismic resisting system design rules for connections between carbon steel members may not be applicable, at least without modification, to connections between stainless steel members. This study has investigated the seismic performance of welded T-shaped beam-column moment resisting connections made of structural stainless steel beams and columns manufactured by laser welding. The paper included the results of three large-scale T-shaped specimens, of varying sizes, subjected to seismic loads. The grade of laser-fused stainless steel was 304 L and its specification was according to ASTM A276. The sections were subject to the seismic tests in accordance with the SAC protocol given in ANSI/AISC 341-10. The results shows substantial amount of energy dissipation by welded moment resisting stainless steel connections along with a high ductility capability and dependable behaviour in the inelastic range.

Repair of glulam beams using GFRP rods

Timber is one of the oldest building materials and is very attractive because it is a renewable resource, recyclable and relatively inexpensive. However, as the service requirements that are imposed on structural members change, mechanical upgrade or repair becomes of increasing importance. This paper describes an experimental test programme which investigates the use of glass fibre reinforced polymer rods (GFRP) for the retrofit of low-grade glue-laminated timber beams, which were tested in bending initially in the unreinforced state for both stiffness and ultimate moment capacity. The test results demonstrated that by correctly carrying out the retrofitting procedure in timber beams that were severely damaged, mechanical strength and flexural stiffness of the original beams could be regained and in addition significant ductility was introduced.