Tension proof loading has been shown to be effective in eliminating low-strength fingerjoints, and a proof load stress level of 1.3 times the allowable stress value was found to be optimum. This confirms the tension proof loading stress requirement of the Canadian National Lumber Grades Authority (NLGA) for fingerjoined lumber.
Proof loading stress levels were chosen at 1.0, 1.3 and 1.6 times the allowable stress, and loading rates were selected so that target stress was attained in 0.2, 6.0 or 60 seconds. The only effect of loading rate was a small increase in strength values for weaker specimens when tested at faster loading rates, along with increased variability; therefore, it is strongly recommended that very fast loading rates be avoided, and a loading rate be chosen so the desired stress level is attained in about one second.
FPInnovations – Forintek performed this two-year study to provide a sound basis for evaluation of the tension proof-loading of fingerjoined lumber. The findings will be useful to the fingerjoined-lumber industry in refining the process and promoting its benefits to end users and regulators.
The objective of the project is to develop/improve practical, reliable and internationally recognized methods for assessing/pre-screening the long-term structural performance of engineered wood products used in residential and non-residential applications.
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.