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.
Fibre-reinforced wood systems are light, strong, stiff composites that can efficiently replace larger wood members and can be relied on to provide consistent mechanical properties.
This report is an introduction to fibre-reinforced wood systems for members of the Canadian wood products industry. It provides the motivation for reinforcing wood with synthetic fibres, and surveys the choice of materials and their uses. Numerous examples of current applications are discussed to demonstrate the strong and weak points of various approaches and examine the durability and management of fibre-reinforced wood products, as well as to indicate opportunities that exist for the Canadian wood products industry.
This report is intended to be a useful reference for the Canadian wood products industry, and assist future developments in structural and non-structural applications of fibre-reinforced wood products.