Pull out Strength of Bonded-In Steel Bars Behavior in Pinus oocarpa Shiede Timber

The study of pull out strength of bonded-in steel bars in Pinus oocarpa Shiede timbers (ρ12% = 550 kg/m3) is presented. The aim was to evaluate, with the design of experiment, statistical methods and experimental works, the moisture content and anchorage areas variations effects. In addition, three angles (0, 45 and 90º), between the rod and the direction of grain were considered and a polyurethane adhesive, based on castor oil, and three epoxy resins were used. The wood specimens were seasoned to the expected moisture contents of 12, 15, 18 and 22%. In each specimen, there were four holes with 9.0 mm diameter and 40, 60, 80 and 120 mm depths. The deformed steel bars with the minimum yield tensile strength of 500 MPa and nominal diameter of 6.3 mm were axially loaded with two load cycles. The results are presented in a comparative form after the statistical analysis. The rupture modes are discussed and the need for a broad understanding of resin behaviour is highlighted. Average anchorage strength presented positive linear relationships, with an increase of the anchorage area and negative linear relationships with increased moisture content for all the resins and directions between steel bar and wood grain studied.