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Effect of on-line tension proof parameters on fingerjoined lumber performance

https://library.fpinnovations.ca/fr/permalink/fpipub37959
Auteur
Pirvu, Ciprian
Date
March 2009
Genre du document
Research report
Domaine
Wood Manufacturing & Digitalization
Auteur
Pirvu, Ciprian
Date
March 2009
Genre du document
Research report
Description physique
87 p.
Secteur
Wood Products
Domaine
Wood Manufacturing & Digitalization
Champ de recherche
Advanced Wood Manufacturing
Sujet
Mechanical properties
Joints
Série
Value to Wood No. FCC 021W
W-2668
Localisation
Vancouver, British Columbia
Langue
English
Résumé
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.
Glued joints - Finger - Strength
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Load duration test protocols for engineered wood products

https://library.fpinnovations.ca/fr/permalink/fpipub37951
Auteur
Pirvu, Ciprian
Date
March 2009
Genre du document
Research report
Domaine
Sustainable Construction
Auteur
Pirvu, Ciprian
Collaborateur
Canada. Canadian Forest Service.
Date
March 2009
Genre du document
Research report
Description physique
12 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Building Systems
Sujet
Mechanical properties
Materials
Building construction
Série
Canadian Forest Service No. 4
W-2653
Localisation
Vancouver, British Columbia
Langue
English
Résumé
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.
Building construction - Materials used - Strength
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State-of-the-art report on fibre reinforced polymer (FRP) utilization in wood products

https://library.fpinnovations.ca/fr/permalink/fpipub41302
Auteur
Pirvu, Ciprian
Date
June 2004
Genre du document
Research report
Domaine
Sustainable Construction
Auteur
Pirvu, Ciprian
Date
June 2004
Genre du document
Research report
Description physique
35 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Materials
Série
W-2073
Localisation
Vancouver, British Columbia
Langue
English
Résumé
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.
Composite materials - Durability
Fibres
Board products - Materials used
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Time-dependent behavior of cross-laminated timber

https://library.fpinnovations.ca/fr/permalink/fpipub43013
Auteur
Pirvu, Ciprian
Date
March 2014
Genre du document
Research report
Domaine
Sustainable Construction
Auteur
Pirvu, Ciprian
Collaborateur
Natural Resources Canada. Canadian Forest Service.
Date
March 2014
Genre du document
Research report
Description physique
70 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Building construction
Design
Laminate product
Panels
Timber
Série
Transformative Technologies No. 1.1.12
W-3092
Langue
English
Résumé
Cross laminated timber (CLT) panels were manufactured and tested to assess their time dependent behaviour. This study is intended to help guide the development of an appropriate test method and acceptance criteria to account for duration of load and creep effects in the design of structures using CLT. Nine CLT panels of different qualities and using different wood species combinations were manufactured at a pre-commercial pilot plant out of local wood species. The CLT panels manufactured in this study were pressed at about 54% lower pressure than the minimum vertical pressure specified by the adhesive manufacturer due to a limitation of the press, so the CLT panels are viewed as a simulated defective sample, which may occur in a production environment due to material- or process-related issues. Full-size CLT panels were initially tested non-destructively to assess their bending stiffness. Then, billets were ripped from the full-size CLT panels, and tested to failure in 1-minute and 10-hour ramp tests, or assessed in creep tests under sustained load. The constant loads imposed on the CLT billets tested in creep were calculated as to allow for a maximum deflection of L/180. Following two cycles of loading and relaxation, the CLT billets tested in creep were further tested to failure at the end. The principles of ASTM D6815-09 and those of an in-house FPInnovations protocol were applied to assess the time dependent behavior of the CLT billets. The main test findings are summarized below:
In terms of residual stiffness, the percentage change in the initial bending stiffness for the CLT billets subjected to the 10-hour ramp test varied between 0-5%, showing a 3% drop in stiffness on average, while that for the CLT billets tested in creep ranged between 0-3%, showing a 1% stiffness drop on average. These are regarded as relatively small changes in bending stiffness.
In general, decreasing creep rates were observed on most of the CLT billets especially in the first cycle up to 90 days. The creep rates went up after 120 days of loading due to an increase in temperature and relative humidity conditions, which greatly affect the rate of deflection and recovery of wood products.
Fractional deflections were calculated for all the CLT billets after 30-day intervals and found to be less than or equal to 1.43.
Creep recovery was above 36% after 30-day, 60-day, and 90-day recovery periods in the first cycle. However, in the second cycle, creep recovery for some CLT billets dropped below 20% for certain time periods. ASTM D6815-09 provides specifications for evaluation of duration of load and creep effects of wood and wood-based products. The standard was designed to accommodate wood products that can be easily sampled, handled, and tested under load for minimum 90 days and up to 120 days. The standard requires a minimum sample size of 28 specimens. Because of its large dimensions, CLT products are not feasible for experiments requiring such large sample sizes. However, the findings of this study revealed potential for some of the acceptance criteria in ASTM D6815-09 to be applied to CLT products. The CLT billets in this study were assessed in accordance to the creep rate, fractional deflection, and creep recovery criteria in ASTM D6815-09 standard. All CLT billets tested in this study showed (1) decreasing creep rates after 90/120 days of loading, (2) fractional deflections less than 2.0 after 90-day loading, and (3) higher creep recovery than 20% after 30 days of unloading, as required by ASTM D6815-09. A single replicate billet was used per CLT configuration instead of the minimum sample size required by the standard which may have an effect on the findings.
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