Skip header and navigation

12 records – page 1 of 2.

Composite Cross Laminated Timber (CCLT) Made with Engineered Wood Products (EWP) and Hardwood

https://research.thinkwood.com/en/permalink/catalogue1578
Year of Publication
2016
Topic
Design and Systems
Cost
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
LSL (Laminated Strand Lumber)
LVL (Laminated Veneer Lumber)
Author
Grandmont, Jean-Frédéric
Wang, Brad
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
LSL (Laminated Strand Lumber)
LVL (Laminated Veneer Lumber)
Topic
Design and Systems
Cost
Mechanical Properties
Keywords
Dimensional Stability
SPF
Birch
Aspen
Maple
Equilibrium Moisture Content
Delamination
Bond Line
Manufacturing
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 1723-1730
Summary
North American cross laminated timber is currently made of softwood lumber following the guidelines of the ANSI/APA PRG-320 manufacturing standard. In this study, the potential of manufacturing CLT panels using various hardwood species and engineered wood products (EWP) was investigated for their compatibility and the impact on the dimensional stability and aesthetics of the end products. Yellow birch, trembling aspen, sugar maple, laminated strand lumber (LSL) and laminated veneer lumber (LVL) were compared to 100% spruce-pine-fir group species (SPF) lumber made CLT panel. The bond line performance of the assemblies was tested as well as the dimensional stability and appearance of the panels when subjected to conditions with equilibrium moisture contents (EMC) of 4.5%, 12% and 16%. Results showed that higher density hardwood species were prone to delamination. LSL, LVL and trembling aspen yielded promising delamination results. Best overall dimensional stability results were achieved with EWP inclusive configurations. Aesthetic integrity assessment showed that the use of hardwood for the core layer and edge gluing of softwood outer layers had a negative impact. Overall, the study showed a great potential for manufacturing future composite CLT (CCLT) products using EWP and low density hardwood species. The cost premium of using these alternative materials would need to be offset by valuable sets of properties or by a reduction of the manufacturing cost.
Online Access
Free
Resource Link
Less detail

Development of Modular System in Midrise to Tall Wood Buildings Phase II

https://research.thinkwood.com/en/permalink/catalogue2530
Year of Publication
2020
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Zhang, Chao
Organization
Timber Engineering and Applied Mechanics (TEAM) Laboratory
Year of Publication
2020
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Design and Systems
Keywords
Openings
Lateral Performance
Shear Walls
SPF
Spruce-Pine-Fir
Loading Tests
Language
English
Research Status
Complete
Summary
This project studied the effect of openings on the lateral performance of CLT shear walls and the system behavior of the walls in a module. Three-layer Cross Laminated Timber (CLT) was used for manufacturing the wall and module specimens. The laminar was Spruce-Pine-Fir (SPF) #2&Better for both the major and minor layers. Each layer was 35 mm thick. The panel size was 2.44 m × 2.44 m. Four configurations of walls were investigated: no opening, 25% opening, 37.5% opening, and 50% opening. The opening was at the center of the wall and in the shape of a square. A CLT module was made from two walls with 50% openings, with an overall thickness of 660 mm. The specimens were tested under monotonic loading and reverse-cyclic loading, in accordance with ASTM E564-06 (2018) and ASTM E2126-19. The wall without opening had an average peak load of 111.8 kN. It had little internal deformation and the failure occurred at the connections. With a 25% opening, deformation within the wall was observed but the failure remained at the connections. It had the same peak load as the full wall. When the opening was increased to 37.5%, the peak load decreased by 6% to 104.9 kN and the specimens failed in wood at the corners of the opening. Further increasing the opening to 50%, the peak load dropped drastically to 63.4 kN, only 57% of the full wall. The load-displacement relationship was approximately linear until the load reached 60% of the peak or more. Compared to the full wall, the wall with 25% opening had 65% of the stiffness. When the opening increased to 37.5% and 50%, the stiffness reduced to 50% and 24% of the full wall, respectively. The relationship between stiffness and opening ratio was approximately linear. The loading protocol had effect on the peak load but not on the stiffness. There was more degradation for larger openings under reverse-cyclic loading. The performance of the module indicated the presence of system effect that improves the ductility of the wall, which is important for the seismic performance of the proposed midrise to tall wood buildings. The test data was compared to previous models found in literature. Simplified analytical models were also developed to estimate the lateral stiffness and strength of CLT wall with openings.
Online Access
Free
Resource Link
Less detail

Durability of Structural Lumber Products after Exposure at 82C and 80% Relative Humidity

https://research.thinkwood.com/en/permalink/catalogue784
Year of Publication
2005
Topic
Mechanical Properties
Moisture
Material
LSL (Laminated Strand Lumber)
LVL (Laminated Veneer Lumber)
Solid-sawn Heavy Timber
Author
Green, David
Evans, James
Hatfield, Cherilyn
Byrd, Pamela
Organization
Forest Products Laboratory
Year of Publication
2005
Country of Publication
United States
Format
Report
Material
LSL (Laminated Strand Lumber)
LVL (Laminated Veneer Lumber)
Solid-sawn Heavy Timber
Topic
Mechanical Properties
Moisture
Keywords
Aspen
Douglas-Fir
Modulus of Elasticity
Modulus of Rupture
Southern Pine
Poplar
Relative Humidity
SPF
Temperature
Flexural Properties
Language
English
Research Status
Complete
Summary
Solid-sawn lumber (Douglas-fir, southern pine, Spruce– Pine–Fir, and yellow-poplar), laminated veneer lumber (Douglas-fir, southern pine, and yellow-poplar), and laminated strand lumber (aspen and yellow-poplar) were heated continuously at 82°C (180°F) and 80% relative humidity (RH) for periods of up to 24 months. The lumber was then reconditioned to room temperature at 20% RH and tested in edgewise bending. Little reduction occurred in modulus of elasticity (MOE) of solid-sawn lumber, but MOE of composite lumber products was somewhat reduced. Modulus of rupture (MOR) of solid-sawn lumber was reduced by up to 50% after 24 months exposure. Reductions in MOR of up to 61% were found for laminated veneer lumber and laminated strand lumber after 12 months exposure. A limited scope study indicated that the results for laminated veneer lumber in edgewise bending are also applicable to flatwise bending. Comparison with previous results at 82°C (180°F)/25% RH and at 66°C (150°F)/20% RH indicate that differences in the permanent effect of temperature on MOR between species of solid-sawn lumber and between solid-sawn lumber and composite lumber products are greater at high humidity levels than at low humidity levels. This report also describes the experimental design of a program to evaluate the permanent effect of temperature on flexural properties of structural lumber, with reference to previous publications on the immediate effect of temperature and the effect of moisture content on lumber properties.
Online Access
Free
Resource Link
Less detail

Enhancing Thermal and Mechanical Performance of Engineered Wood Product Adhesives using Novel Fire Retardant Nanoclays

https://research.thinkwood.com/en/permalink/catalogue2810
Year of Publication
2021
Topic
Mechanical Properties
Fire
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Oguzlu-Baldelli, Hale
Yu, Jason
Lee, George
Lam, Frank
Jiang, Feng
Organization
University of British Columbia
Year of Publication
2021
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Fire
Keywords
Adhesive
PUR
Bond Strength
Halloysite
pMDI
Douglas-Fir
SPF
Bonding Shear Strength
Language
English
Research Status
Complete
Summary
One component PUR adhesive is widely used in engineered wood products applications, such as cross-laminated timber (CLT). However, the dramatic deterioration of PUR adhesive bond strength at elevated temperature can out tremendously threat for tall wood building, especially under fire. In this project, we are aiming to improving the bond strength of the PUR adhesive at high temperature by incorporating chemically modified halloysite to improve the poor interface between inorganic fillers and the polymer matrices. To improve the interaction with PUR (Loctite UR20 by Henkel®), the halloysite was chemically grafted with polymeric diphenylmethane diisocyanate (pMDI) (pMDI-H). The effect of adding pMDI modified halloysite to the PUR adhesives was investigated in terms of nanofiller dispersibility, thermal and mechanical properties of the pMDI-halloysite-PUR composite film, and the bonding shear strength of the glued Douglas fir and Spruce-Pine-Fir (SPF) shear blocks under different temperature. Significant improvement of the bond shear strength can be observed with the addition of 5 and 10% of pMDI-modified PUR adhesive, and the key research findings are summarized as below, a. pMDI can be successfully grafted onto hydroxylated halloysites to improve its dispersibility in one-component PUR adhesive; b. Addition of pMDI-H into PUR adhesive can lead to improved glass transition temperature and storage modulus. In contrast, no significant enhancement was observed in h-H added PUR films due to the poor dispersibility; c. Addition of up to 10% h-H and pMDI-H did not show significant change of the shear strength at 20 °C for both Douglas Fir and SPF; d. Significant enhancement of shear strength at elevated temperature (60-100 °C) can be observed for 5% and 10% pMDI-H modified PUR adhesive, showing 17% improvement for Douglas Fir and 27-37% for SPF.
Online Access
Free
Resource Link
Less detail

Evaluating Rolling Shear Strength Properties of Cross Laminated Timber by Torsional Shear Tests and Bending Test

https://research.thinkwood.com/en/permalink/catalogue307
Year of Publication
2014
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Li, Minghao
Lam, Frank
Li, Yuan
Year of Publication
2014
Country of Publication
New Zealand
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
SPF
Polyurethane
Rolling Shear Strength
Torsional Shear Test
Bending Test
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
This paper presents a study on evaluating rolling shear (RS) strength properties of cross laminated timber (CLT) using torsional shear tests and bending tests. The CLT plates were manufactured with Spruce-Pine-Fir boards and glued with polyurethane adhesive. Two types of layups (3-layer and 5-layer) and two clamping pressures (0.1 MPa and 0.4 MPa) were studied. For the torsional shear tests, small shear block specimens were sampled from the CLT plates and the cross layers were processed to have an annular cross section. Strip specimens were simply sampled from the CLT plates for the bending tests. Based on the failure loads, RS strength properties were evaluated by torsional shear formula, composite beam formulae as well as detailed finite element models, respectively. It was found that the two different test methods yielded different average RS strength value for the same type of CLT specimens. The test results showed that the CLT specimens pressed with the higher clamping pressure had slightly higher average RS strength. The specimens with thinner cross layers also had higher RS strength than the specimens with thicker cross layers.
Online Access
Free
Resource Link
Less detail

Exploring Cross-Laminated Timber Use for Temporary Military Structures: Ballistic Considerations

https://research.thinkwood.com/en/permalink/catalogue2371
Year of Publication
2018
Topic
Design and Systems
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Sanborn, Kathryn
Publisher
Georgia Institute of Technology
Year of Publication
2018
Country of Publication
United States
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Market and Adoption
Keywords
Ballistic Resistance
Panels
Military Structures
Blast Analysis Tool
Spruce-Pine-Fir
Southern Pine
SPF
Language
English
Research Status
Complete
Summary
The design and construction of temporary military structures has changed little since World War II. While these structures are lightweight and rapidly deployable, they require a sizeable workforce to construct and provide minimal ballistic and blast protection for occupants. Cross-laminated timber (CLT) is a relatively new prefabricated engineered wood product that is strong, stiff, quick to build, and has the potential to offer inherent ballistic and blast resistance compared to traditional wood products. The orthotropic nature of CLT coupled with the energy absorbing capacity of the thick wood panels warrant further investigation into the viability of CLT for temporary military structures. To that end, the research presented in this thesis seeks to better understand the ballistic and blast response of CLT panels and to develop evaluation criteria for the use of CLT in temporary military structures. Specific areas of investigation included: 1) experimental testing of the ballistic resistance of CLT panels, conducting in conjunction with U.S. Army laboratories in Aberdeen Proving Grounds, Maryland and Vicksburg, Mississippi; 2) the design, prototyping, and experimental testing of enhanced CLT panels to further improve ballistic performance; 3) a qualitative analysis of CLT panels under ballistic impact resistance mechanisms; 4) the development of a CLT blast analysis tool to predict the elastic response of CLT to blast loadings; and 5) the development of a simplified tool to identify evaluation criteria for temporary military structure material selection, including conventional materials as well as CLT. Specimens in this research consisted of commercially produced Spruce-Pine-Fir CLT as well as Southern Pine CLT specimens fabricated specifically for this research. Ballistic testing of both types of conventional CLT indicate that the material’s inherent penetration resistance is significantly greater than that of dimension lumber and plywood used in current common temporary military structures. The testing shows that current U.S. military design guidelines (UFC 4-023-07), used for determining required wood thickness based on ballistic threat, under predicts the ballistic performance of CLT. From testing and analysis, the thesis develops updated equations for predicting the thickness of CLT required for ballistic protection. A qualitative analysis of ballistic specimens identified local failure modes in the CLT and links the observed damage the anisotropic material properties, grading, and defects in sawn timbers. Enhanced CLT specimens were fabricated using various hardening materials including thin metal plates and gratings, polymer-based armors, and fiber-reinforced epoxy matrix panels. The enhanced CLTs were evaluated based on ease of production, ballistic resistance as compared to conventional CLT, and cost-benefit analysis. The shear analogy method was incorporated into a single-degree-of-freedom blast analysis to predict the response of different types and sizes of CLT panels under blast loads within the elastic regime. The tool was validated using field data from low-level live blast tests and showed good agreement with the field data. Finally, tailored evaluation criteria for comparative assessment of construction materials for use in temporary military structures – considering issues of cost, the logistics of in-theater deployment, energy consumption and force protection were developed and applied through using the AHP decision-making process.
Online Access
Free
Resource Link
Less detail

Fire Resistance of Unprotected CLT Floors & Walls Manufactured in the U.S.

https://research.thinkwood.com/en/permalink/catalogue2262
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Organization
TallWood Design Institute
Country of Publication
United States
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Fire
Keywords
Douglas-Fir
SPF
Connections
Adhesives
Structural Integrity
Research Status
In Progress
Notes
Contact: Lech Muszynski, Oregon State University
Summary
This project will document the flammability of Douglas-fir and spruce-pine-fir CLT panel assemblies produced in the United States. Tests are being conducted on wall and floor panel assemblies with standard overlapping connections and produced with two different types of commonly-used adhesives. Sensors placed throughout panels will provide data about how fire affects the interior and exterior of a panel. A thermal imaging camera will provide information on how the structural integrity of panels is affected by fire and fire suppression activities.
Less detail

Fire Resistance of Unprotected Cross-Laminated Timber (CLT) Floor Assemblies Produced in the USA

https://research.thinkwood.com/en/permalink/catalogue2507
Year of Publication
2019
Topic
Fire
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Floors
Wood Building Systems

Fire Safe Glued Massive Timber Members Adhesive Bonding Performance under Elevated Temperature -Tests Report

https://research.thinkwood.com/en/permalink/catalogue169
Year of Publication
2013
Topic
Fire
Mechanical Properties
Material
Solid-sawn Heavy Timber
Author
Zhang, Chao
Yan, Huijun
Lee, George
Lam, Frank
Organization
Forestry Innovation Investment
Year of Publication
2013
Country of Publication
Canada
Format
Report
Material
Solid-sawn Heavy Timber
Topic
Fire
Mechanical Properties
Keywords
Temperature
Adhesives
Bondlines
Polyurethane
Douglas-Fir
Hemlock
SPF
Phenol-Resorcinol Formaldehyde
Epoxy
Language
English
Research Status
Complete
Summary
This project was conducted to quantify the performance of adhesives bond lines under shear load subject to elevated temperature. The results add to the understanding of the performance of polyurethane adhesive bond lines under elevated temperatures to address areas of fire safety concern under the current building codes. The project focused on studying the shear bond capacity of three wood species by using 3 types of adhesives with/without nanoclay treatment at 4 temperature levels. The three wood species are Douglas-Fir, Hemlock and SPF. The adhesives are polyurethane (PU), Phenol-Resorcinol-Formaldehyde (PRF) and Epoxy. PU and PRF specimens were also tested with nanoclay treatment and without nanoclay treatment. Epoxy specimens were tested without nanoclay treatment only. The temperature levels considered were room temperature (about 20 °C), 60°C, 80°C and 100°C. The results indicate that the influence of elevated temperature on the shear bond strength of PU and PRF adhesive was in the range of 20 to 30% regardless of nanoclay treatment. Regardless of species, PU or PRF, with or without nanoclay, the average shear strength for 100°C oven temperature treatment ranged from 6.0 to 7.5 MPa. In the case of SPF PU specimens treatment with nanoclay reduced the variability of shear strength significantly from 12% at room temperature to 5% after 100°C oven treatment. This is an important aspect that needs further verification for enhancement of performance. Finally the data in this study can be used to support modeling of timber component subjected to elevated temperature.
Online Access
Free
Resource Link
Less detail

Moisture Response of Wall Assemblies of Cross-Laminated Timber Construction in Cold Canadian Climates

https://research.thinkwood.com/en/permalink/catalogue143
Year of Publication
2012
Topic
Serviceability
Moisture
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Lepage, Robert
Organization
University of Waterloo
Year of Publication
2012
Country of Publication
Canada
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Serviceability
Moisture
Keywords
Canada
Climate
Decay
Durability
Hem-Fir
Hygrothermal
Mold
Relative Humidity
Rot
Simulation
SPF
Water Vapour Permeability
Language
English
Research Status
Complete
Summary
Wood is a highly versatile renewable material (with carbon sequestering properties), that is light in weight, has good strength properties in both tension and compression while providing good rigidity and toughness, and good insulating properties (relative to typical structural materials). Engineered wood products combine the benefits of wood with engineering knowledge to create optimized structural elements. Cross-laminated timber (CLT), as one such engineered wood product, is an emerging engineering material which provides great opportunities for the building industry. While building with wood has many benefits, there are also some concerns, particularly decay. Should wood be exposed to elevated amounts of moisture, rots and moulds may damage the product or even risk the health of the occupants. As CLT panels are a relatively new engineered wood product, the moisture characteristics have yet to be properly assessed.
Online Access
Free
Resource Link
Less detail

12 records – page 1 of 2.