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Block Shear Testing of CLT Panels: An Exploratory Study

https://research.thinkwood.com/en/permalink/catalogue2624
Year of Publication
2011
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Casilla, Romulo
Pirvu, Ciprian
Wang, Brad
Lum, Conroy
Organization
FPInnovations
Year of Publication
2011
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Adhesive
Block Shear Test
Failure
Language
English
Research Status
Complete
Summary
A study was conducted with the primary objective of examining the efficacy of a standard block shear test method to assess the bond quality of cross-laminated timber (CLT) products. The secondary objective was to examine the effect of pressure and adhesive type on the block shear properties of CLT panels. The wood material used for the CLT samples was Select grade nominal 25 x 152-mm (1 x 6-inch) Hem-Fir. Three adhesive types were evaluated under two test conditions: dry and vacuum-pressure-dry (VPD), the latter as described in CSA standard O112.10. Shear strength and wood failure were evaluated for each test condition. Among the four properties evaluated (dry and VPD shear strength, and dry and VPD wood failure), only the VPD wood failure showed consistency in assessing the bond quality of the CLT panels in terms of the factors (pressure and adhesive type) evaluated. Adhesive type had a strong effect on VPD wood failure. The different performance levels of the three adhesives were useful in providing insights into how the VPD block shear wood failure test responds to significant changes in CLT manufacturing parameters. The pressure used in fabricating the CLT panels showed a strong effect on VPD wood failure as demonstrated for one of the adhesives. VPD wood failure decreased with decreasing pressure. Although dry shear wood failure was able to detect the effect of pressure, it failed to detect the effect of adhesive type on the bond quality of the CLT panels. These results provide support as to the effectiveness of the VPD block shear wood failure test in assessing the bond quality of CLT panels. The VPD conditioning treatment was able to identify poor bondline manufacturing conditions by observed changes in the mode of failure, which is also considered an indication of wood-adhesive bond durability. These results corroborate those obtained from the delamination test conducted in a previous study (Casilla et al. 2011). Along with the delamination test proposed in an earlier report, the VPD block shear wood failure can be used to assess the CLT bond quality. Although promising, more testing is needed to assess whether the VPD block shear wood failure can be used in lieu of the delamination test. The other properties studied (shear strength and dry wood failure), however, were not found to be useful in consistently assessing bond line manufacturing quality.
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Checking in CLT Panels: An Exploratory Study

https://research.thinkwood.com/en/permalink/catalogue2625
Year of Publication
2011
Topic
Moisture
Material
CLT (Cross-Laminated Timber)
Author
Casilla, Romulo
Lum, Conroy
Pirvu, Ciprian
Wang, Brad
Organization
FPInnovations
Year of Publication
2011
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Moisture
Keywords
Panels
Testing Methods
Surface Checks
Moisture Content
Gaps
Language
English
Research Status
Complete
Summary
A study was conducted with the primary objective of gathering information for the development of a protocol for evaluating the surface quality of cross-laminated timber (CLT) products. The secondary objectives were to examine the effect of moisture content (MC) reduction on the development of surface checks and gaps, and find ways of minimizing the checking problems in CLT panels. The wood materials used for the CLT samples were rough-sawn Select grade Hem-Fir boards 25 x 152 mm (1 x 6 inches). Polyurethane was the adhesive used. The development of checks and gaps were evaluated after drying at two temperature levels at ambient relative humidity (RH). The checks and gaps, as a result of drying to 6% to 10% MC from an initial MC of 13%, occurred randomly depending upon the characteristics of the wood and the manner in which the outer laminas were laid up in the panel. Suggestions are made for minimizing checking and gap problems in CLT panels. The checks and gaps close when the panels are exposed to higher humidity. Guidelines were proposed for the development of a protocol for classifying CLT panels into appearance grades in terms of the severity of checks and gaps. The grades can be based on the estimated dimensions of the checks and gaps, their frequency, and the number of laminas in which they appear.
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Delamination Testing of CLT Panels: An Exploratory Study

https://research.thinkwood.com/en/permalink/catalogue2626
Year of Publication
2011
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Casilla, Romulo
Pirvu, Ciprian
Wang, Brad
Organization
FPInnovations
Year of Publication
2011
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Adhesive
Bond Quality
Delamination Test
Strength
Language
English
Research Status
Complete
Summary
A study was conducted with the primary objective of examining the efficacy of delamination test using cylindrical core specimens to assess the bond quality of cross laminated timber (CLT) products. A prototype coring drill bit was fabricated to prepare a cylindrical-shaped specimen, the height of which corresponds to the full thickness of the CLT panel. A secondary objective was to examine the effect of pressure, adhesive type, number of plies, and specimen shape on the delamination resistance of CLT panels. The wood material used for the CLT samples was Select grade nominal 1 x 6-inch Hem-Fir boards. Examples of three adhesive types were evaluated, which were designated as A, B, and C. The delamination tests used were as described in CAN / CSA O122-06 and EN 302-2. Cylindrical specimen extracted as core was found satisfactory as a test specimen type for use in delamination testing of CLT product. Its efficacy was comparable to that of a square cross-section specimen. The former is recommended as it can be extracted from thicker panels and from any location in the panel. It would also be more convenient to plug the round hole. Adhesive type had a strong effect on delamination resistance based on the two delamination tests used. Adhesive A exhibited the greatest delamination resistance, followed in decreasing order, by adhesives C and B. It should be noted that no effort was made to find the optimum CLT manufacturing parameters for each type of adhesive. Therefore the relative rankings of the adhesives tested may not be representative. However, for the purposes of this study, the different performance levels from the three adhesives are useful in providing insight into how the proposed delamination test responds to significant changes in CLT manufacturing parameters. Pressure used in fabricating the CLT panel showed a strong effect on delamination resistance as demonstrated for one of the adhesives. Delamination resistance decreased with decreasing pressure. The effect of the number of plies in the CLT panel was dependent upon the type of adhesive, and this was probably related to the adhesive’s assembly time characteristic. These results provide support as to the effectiveness of delamination test in assessing the moisture durability of CLT panels. It was able to differentiate the performance in delamination resistance among different types of adhesives, and able to detect the effect of manufacturing parameters such as pressure and increased number of plies in CLT construction. The test procedure described in CAN / CSA O122-06 appears to be reasonable in the delamination resistance assessment of CLT panels for qualification and quality control testing. Based on the results of the study along with some background information and guidelines, delamination requirements for CLT panels are proposed. The permitted delamination values are greater than those currently specified for laminated and fingerjoined lumber products. This is in recognition of the higher bond line stresses when bonded perpendicular laminations (i.e. CLT) are exposed to the delamination wetting and drying cycles, as opposed to parallel laminations (i.e. glulam or fingerjoints).
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Development of Design Values for Hem-Fir Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue116
Year of Publication
2015
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Pirvu, Ciprian
Organization
FPInnovations
Year of Publication
2015
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Hem-Fir
Visually graded
Machine Stress Rated
Durability
Bondlines
Canada
US
Language
English
Research Status
Complete
Summary
The North American product standard for performance-rated cross-laminated timber (CLT), ANSI/APA PRG 320, was published in 2012. The standard recognizes the use of all major Canadian and US softwood species groups for CLT manufacturing and provides design...
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In-Situ Testing at Wood Innovation and Design Centre: Floor Vibration, Building Vibration, and Sound Insulation Performance

https://research.thinkwood.com/en/permalink/catalogue284
Year of Publication
2015
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Author
Hu, Lin
Pirvu, Ciprian
Ramzi, Redouane
Organization
FPInnovations
Year of Publication
2015
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Topic
Acoustics and Vibration
Keywords
Natural Frequency
Damping Ratio
Static Deflection Testing
Vibration Performance
Sound Transmission
Language
English
Research Status
Complete
Summary
In order to address the lack of measured natural frequencies and damping ratios for wood and hybrid wood buildings, and lack of knowledge of vibration performance of innovative CLT floors and sound insulation performance of CLT walls and floors, FPInnovations conducted...
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The North American Product Standard for Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue760
Year of Publication
2012
Topic
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Author
Yeh, Borjen
Gagnon, Sylvain
Williamson, Tom
Pirvu, Ciprian
Lum, Conroy
Kretschmann, David
Publisher
Forest Products Society
Year of Publication
2012
Country of Publication
United States
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Market and Adoption
Keywords
International Building Code
North America
Standards
Language
English
Research Status
Complete
Series
Wood Design Focus
Online Access
Free
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Sound Insulation Performance of Elevator Shaft Walls built with Nail-Laminated Timber Panels - Exploratory Tests and Preliminary Results

https://research.thinkwood.com/en/permalink/catalogue364
Year of Publication
2016
Topic
Acoustics and Vibration
Material
NLT (Nail-Laminated Timber)
Application
Shafts and Chases
Author
Pirvu, Ciprian
Organization
FPInnovations
Year of Publication
2016
Country of Publication
Canada
Format
Report
Material
NLT (Nail-Laminated Timber)
Application
Shafts and Chases
Topic
Acoustics and Vibration
Keywords
Building Codes
Canada
Sound Insulation
Apparent Sound Insulation Class
Language
English
Research Status
Complete
Summary
As 6-storey wood-frame, massive-timber and hybrid wood buildings are increasingly accepted by more jurisdictions across Canada, there is a need to develop reliable elevator shaft designs that meet the minimum structural, fire, and sound requirements in building...
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Time-Dependent Behavior of Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1111
Year of Publication
2014
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Pirvu, Ciprian
Organization
FPInnovations
Year of Publication
2014
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Creep
Duration of Load
Time Dependent Behavior
Stiffness
Deflection
Language
English
Research Status
Complete
Summary
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.
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US Edition - Chapter 6: Duration of Load and Creep Factors for Cross-Laminated Timber Panels

https://research.thinkwood.com/en/permalink/catalogue825
Year of Publication
2013
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Pirvu, Ciprian
Douglas, Bradford
Yeh, Borjen
Organization
FPInnovations
Binational Softwood Lumber Council
Year of Publication
2013
Country of Publication
Canada
United States
Format
Guide
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Creep
Duration of Load
Time Dependent Behavior
Language
English
Research Status
Complete
Series
CLT Handbook - US Edition
ISBN
978-0-86488-553-1
ISSN
1925-0495
Summary
Cross-laminated timber (CLT) products are used as load-carrying slab and wall elements in structural systems, thus load duration and creep behavior are critical characteristics that must be addressed in structural design. Given its lay-up construction with orthogonal arrangement of layers bonded with structural adhesive, CLT is more prone to time-dependent deformations under load (creep) than other engineered wood products such as structural glued-laminated timber. Time dependent behavior of structural wood products is addressed in design standards by load duration factors that adjust design properties. Since CLT has been recently introduced into the North American market, the current design standards and building codes do not specify load duration and creep adjustment factors for CLT. Until this can be rectified, an approach is proposed in this Chapter for adopter of CLT systems in the United States. This includes not only load duration and service factors, but also an approach to accounting for creep in CLT structural elements.
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9 records – page 1 of 1.