In the construction of buildings, the timber-concrete (TCC) system can be a cost-competitive solution for floors with longer spans, since the mechanical properties of the two materials are used efficiently. Furthermore, the additional mass from the concrete improves the acoustic performance compared to a timber floor system alone. Nevertheless, TCC floors are not commonly used in buildings in Canada, due to the absence of technical guidelines for such types of structural systems in this country.
Forintek has completed a two-year investigation of the NLGA SPS 6 Standard, Special Products Standard for Structural Face-Glued Lumber. The NLGA SPS 6 Standard prescribes product specifications and qualification and quality control requirements for structural products created by edge-gluing and/or fingerjoining lumber segments. Under the NLGA SPS 6 Standard, the design values assigned are based on the visual grade and the stress level achieved in qualification tests on the glue joints.
The project assessed the effect of the following three factors on strength of the NLGA SPS 6 product:
1. Tension proof-loading;
2. Relative location of fingerjoints in adjacent members when fingerjoined material is edge-glued;
3. Strength of the material used to make the NLGA SPS 6 product.
Results showed a positive effect of proof-loading, a minor effect of staggering of fingerjoints, and a highly significant effect of density of raw material on tensile stress of edge-glued specimens. It was confirmed that SPS6 products of greater commercial value can be obtained from lower grade lumber. However, visual grading of SPS 6 products proved to be more difficult than visual grading of lumber, because grade-determining wood characteristics were sometimes hidden in the bond line, and could not be properly identified.
The findings of this project can be used to fine tune the NLGA SPS 6 standard and the other NLGA fingerjoint and face-glued lumber product standards. The project will help the wood industry maximize the utilization of their raw material resource, resulting in increased profitability.
An above-ground field test of glulam and laminated veneer test samples protected by a combination of coating and treatment with borate by two alternative processes was initiated. Assessment of coating and sample preparation are described.
The project objective is to provide key data on the laminating properties of Canadian wood species to assist the secondary manufacturing industry to meet domestic and international customer expectations. This is a progress report to March 31, 1999.
This study was conducted with the aim of assessing the effects of log storage time and conditions at a BC mill yard on veneer production under mill production conditions. The second objective was to validate the FPInnovations LogdryTM drying model for developed for wood piles in Eastern Canadian mills. The software was used to generate drying rate predictions under the BC mill’s prevailing weather conditions and storage times for comparison with some measured residual moisture contents of Douglas fir logs kept in storage at the mill for six and nine months, sampled and peeled in a laboratory trial in 2016.
The 2016 lab trials suggested little effect of lengthy (winter) storage up to 9 months but mill experience suggests this is excessively long and logs deteriorate in terms of veneer production and quality considerably earlier. Unfortunately due to experimental circumstances the mill peeling trials for the 9 month stored logs were unable to provide an accurate assessment of the true effect on production. Mills trials indicated % heavy sap had remained fairly stable largely within the mill target of 14% to 17% over the storage periods. During the mill trials there were unavoidable heavy confounding effects of different average diameter for log groups and peeler knife condition affecting the expected veneer production variables.
The trials also demonstrated how pile size and height play a major role in protecting logs from drying; with very dry logs having a deleterious effect on veneer production. Logs held in small piles for 12 months or more, even with artificial ‘drying retardants’ such as end sealant and tarping were too dry for reliable peeling, causing very rapid knife wear, spinouts, veneer break-up and line blockages and significant lost recovery. The % heavy sap offtakes from these trials were just 2% to 4%.
LogDryTM provides a fairly good estimate of likely drying rate trends of mid-sized (35 cm/14” to 41 cm/16” range) Douglas fir under the BC mills historic weather conditions over 6 and 9 months.
LogDryTM (Birch setting) was closest to measured log MC in large diameter (46 cm/18”) logs but the Aspen setting was closer to measured MC in small logs (<30 cm/12”). In the limited sample of logs available from the mill in 2016 the 12” logs were much drier after 9 months storage than the model predicted, even on the Aspen setting. Further sampling of piled logs in the small diameter range is needed to verify this observation.
LogDryTM was used to estimate drying rates of logs stored before or after Summer. Modelling indicated a shorter viable storage window for logs delivered before Summer compared to just before Winter, especially in the 6-month range. Residual log MCs were very similar after 12 months regardless of start time.
Further work is required to better calibrate LogdryTM for major Western Canadian species, particularly Douglas fir, Spruce and Lodgepole pine, and reduce the calculation time for simulations. Further adjustment may be needed for simulating real drying rates in very small logs. The model assumption of similar residual MC after 12 months regardless of start time also needs to be verified.
A database has been developed to support the expanding use of glulam in non-residential applications. The increase in the use of glulam requires high-value laminating lumber. Other wood products such as purlins and sheathing material usually are also required when glulam members are used in structure. The database contains test results on laminating lumber grades, finger joints, and 14t-E and 12c-E grade spruce/lodgepole pine/Jack pine glulam members, and theoretical and experimental results on glulam trusses with punched metal plate joints. This database is expected to provide the basis for reliability-based design values for glulam in the 1994 edition of the Canadian Engineering Design Standard for Wood (CSA-O86.1). It also makes possible a new glulam application, metal plated glulam trusses. It is anticipated that the engineering design community, glulam industry, laminating lumber producers, wood truss fabricators, and metal truss plate manufacturers will benefit from the technical information developed in this project.
This progress report contains work performed for the project "Non-residential Applications of Glulam". It includes the experimental and analytical results obtained on laminating lumber grades, finger joints, tension and compression glulam grades, truss plate/glulam joints, and metal- plated glulam trusses.