The relationship between proof load level of fingerjoined lumber and degree of cure of adhesive bonds was investigated. Tension tests were completed for two different degrees of cure for two different adhesives. The proof load level determined for the partially cured joints did not cause damage to the joints that survived the proof test.
Preliminary guidelines for determining appropriate proof load levels for testing fingerjoined lumber with partially cured joints were proposed. The proposed guidelines will need to be validated through mill trials to demonstrate their efficacy and reliability to the manufacturer and third party inspection agency.
Keywords: fingerjoined lumber; tension proof testing/loading; partially cured adhesive bonds.
Duration of load (DOL) and creep effects characterize rheological behaviour of wood and are of critical importance to timber engineering. These effects are accounted for in the engineering design codes with adjustment factors for structural wood and wood-based products. Various methods are used worldwide for the evaluation of DOL and creep effects and for determination of appropriate adjustment factors. A review of the major international codes for engineering design in wood was carried out to understand how DOL and creep are taken into account in these codes and provide recommendations on how to level out the main differences between the codes. It is recommended to adopt an internationally recognized method for evaluation of DOL and creep, and suggestions for the contents of such a method are provided.
Statisticians were engaged to evaluate the damage accumulation models used in wood industry for assessing DOL and creep effects of wood products. The research undertaken yielded answers to whether the mathematical models can be improved, if times-to-failure for ramp and constant load tests can be approximated by Weibull or log-normal distributions, and whether some model parameters can be assumed constant and other treated as random effects. An experimental study was carried out to support the statistical work. The results of the study were used in statistical simulations to estimate the parameters used in the damage accumulation models in an attempt to refine the current models.