Skip header and navigation

22 records – page 1 of 3.

An Overview of CLT Research and Implementation in North America

https://research.thinkwood.com/en/permalink/catalogue759
Year of Publication
2016
Topic
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Author
Pei, Shiling
Rammer, Douglas
Popovski, Marjan
Williamson, Tom
Line, Philip
van de Lindt, John
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Market and Adoption
Keywords
Market
North America
Building Development
Research
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria
Summary
Although not yet seen as common practice, building with cross laminated timber (CLT) is gaining momentum in North America. Behind the scenes of the widely publicized project initiatives such as the Wood Innovation Design Centre Building in Canada and the recent U.S. Tall Wood Building Competition, substantial research, engineering, and development has been completed or is underway to enable the adoption of this innovative building system. This paper presents a brief overview of the current status of CLT building development in North America, highlighting some recent U.S. and Canadian research efforts related to CLT system performance, and identifies future CLT research directions based on the needs of the North American market. The majority of the research summarized herein is from a recent CLT research workshop in Madison, Wisconsin, USA, organized by the USDA Forest Products Laboratory. The opportunity and need for coordination in CLT research and development among the global timber engineering community are also highlighted in the conclusions of this paper.
Online Access
Free
Resource Link
Less detail

A Comparative Cradle-To-Gate Life Cycle Assessment of Mid-Rise Office Building Construction Alternatives: Laminated Timber or Reinforced Concrete

https://research.thinkwood.com/en/permalink/catalogue52
Year of Publication
2012
Topic
Energy Performance
Environmental Impact
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Author
Robertson, Adam
Lam, Frank
Cole, Raymond
Publisher
MDPI
Year of Publication
2012
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Topic
Energy Performance
Environmental Impact
Keywords
Concrete
Embodied Carbon
Life-Cycle Assessment
Mid-Rise
National Building Code of Canada
NBCC
North America
Office Buildings
Research Status
Complete
Series
Buildings
Summary
The objective of this project was to quantify and compare the environmental impacts associated with alternative designs for a typical North American mid-rise office building. Two scenarios were considered; a traditional cast-in-place, reinforced concrete frame and a laminated timber hybrid design, which utilized engineered wood products (cross-laminated timber (CLT) and glulam). The boundary of the quantitative analysis was cradle-to-construction site gate and encompassed the structural support system and the building enclosure. Floor plans, elevations, material quantities, and structural loads associated with a five-storey concrete-framed building design were obtained from issued-for-construction drawings. A functionally equivalent, laminated timber hybrid design was conceived, based on Canadian Building Code requirements. Design values for locally produced CLT panels were established from in-house material testing. Primary data collected from a pilot-scale manufacturing facility was used to develop the life cycle inventory for CLT, whereas secondary sources were referenced for other construction materials. The TRACI characterization methodology was employed to translate inventory flows into impact indicators. The results indicated that the laminated timber building design offered a lower environmental impact in 10 of 11 assessment categories. The cradle-to-gate process energy was found to be nearly identical in both design scenarios (3.5 GJ/m2), whereas the cumulative embodied energy (feedstock plus process) of construction materials was estimated to be 8.2 and 4.6 GJ/m2 for the timber and concrete designs, respectively; which indicated an increased availability of readily accessible potential energy stored within the building materials of the timber alternative.
Online Access
Free
Resource Link
Less detail

Comparison of Environmental Performance of a Five-Storey Building Built with Cross-Laminated Timber and Concrete

https://research.thinkwood.com/en/permalink/catalogue65
Year of Publication
2012
Topic
Energy Performance
Environmental Impact
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Chen, Yue
Organization
University of British Columbia
Year of Publication
2012
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Energy Performance
Environmental Impact
Keywords
Canada
Concrete
Energy Consumption
Environmental
Mid-Rise
North America
Office Buildings
Passive Buildings
Research Status
Complete
Summary
Cross Laminated Timber (CLT), which is made by laminating dimension lumber at right angles, is an innovative high-performance building material that offers many positive attributes including renewability, high structural stability, storage of carbon during the building life, good fire resistance, possibility of material recycling and reuse. It is conceptually a sustainable and cost effective structural timber solution that can compete with concrete in non-residential and multi-family mid-rise building market. Therefore, there is a need to understand and quantify the environmental attribute of this building system in the context of North American resources, manufacturing technology, energy constraints, building types, and construction practice. This study is to compare energy consumption of two building designs using different materials, i.e. CLT and concrete. The designs were based on a five-storey office building, Discovery Place-Building 12, which is located in Burnaby, British Columbia, at 4200 Canada Way. The existing building was built with reinforced concrete. Embodied energy was calculated based on the total amount of material required for each of the building systems. Operational energy was calculated using eQUEST, an energy usage modeling software tool. The environmental impacts of the buildings were evaluated by comparing the total energy consumption through the building life. CLT has lower non-renewable energy consumption compared to concrete in terms of material acquisition, manufacturing and transportation. Previous studies shew that operational energy accounts for the main amount of total energy use in buildings during their service life. Hence, the importance of embodied energy increases by reducing operational energy consumption. CLT has lower embodied energy compared to concrete. Therefore, the advantage of using CLT as a construction material is becoming greater by designing low energy or passive buildings.
Online Access
Free
Resource Link
Less detail

Comparisons of the Production Standards for Cross Laminated Timber (CLT) in Europe versus USA

https://research.thinkwood.com/en/permalink/catalogue1705
Year of Publication
2016
Topic
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Author
Young, Timothy
Barbu, Marius
Hindman, Daniel
Weissensteiner, Josef
Tudor, Eugenia
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Market and Adoption
Keywords
Europe
North America
Manufacturing
Standards
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 4412-4419
Summary
Cross laminated timber (CLT) is a new engineered wood product that has experienced rapid growth and market acceptance for residential and non-residential construction in western and central Europe. Potential exists for rapid market adoption in North America if manufacturing capacities are developed. Dissemination of information on CLT North America markets, manufacturing capabilities, and product standards are the next key steps for facilitating investment in CLT manufacturing capacities in North America. This paper compares standards for CLT between Europe and North America.
Online Access
Free
Resource Link
Less detail

Controlled Rocking Cross-Laminated Timber Walls for Regions of Low-to-Moderate Seismicity

https://research.thinkwood.com/en/permalink/catalogue1726
Year of Publication
2016
Topic
Design and Systems
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Kovacs, Mike
Wiebe, Lydell
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Design and Systems
Seismic
Keywords
North America
Canada
Nonlinear Time History Analysis
Prototype
Controlled Rocking Heavy Timber Walls
Drifts
Energy Dissipation
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 4671-4680
Summary
Controlled rocking heavy timber walls (CRHTW) were originally developed in New Zealand as a lowdamage seismic force resisting system using Laminated Veneer Lumber (LVL). This paper examines one way of adapting them to regions of low-to-moderate seismicity in North America, using Cross-Laminated Timber (CLT) composed of Canadian timber species. In particular, the adaptation simplifies the CRHTW by omitting supplemental energy dissipation and minimizing the potential for long-term damage to the timber from the post-tensioning. Key assumptions that are used in the design and analysis stages are evaluated with regard to the difference between timber products, and the structural performance of a prototype CRHTW design is confirmed by nonlinear time history analysis. Despite the lack of supplemental energy dissipation, the prototype design performs well with negligible residual drifts and a median peak roof drift of 0.63%. Future research is identified for the continued development of the adapted CRHTW.
Online Access
Free
Resource Link
Less detail

Design Models for CLT Shearwalls and Assemblies Based on Connection Properties

https://research.thinkwood.com/en/permalink/catalogue369
Year of Publication
2014
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Popovski, Marjan
Gavric, Igor
Organization
FPInnovations
Year of Publication
2014
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Connections
Keywords
Lateral Loads
Analytical Model
North America
Europe
Research Status
Complete
Summary
The work presented in this report is a continuation of the FPInnovations' research project on determining the performance of the CLT as a structural system under lateral loads. As currently there are no standardized methods for determining the resistance of CLT shearwalls under lateral loads, the design approaches are left at the descretion of the designers. The most common approach that is currently used in Europe and North America assumes that the resistance of CLT walls is a simple summary of the shear resistance of all connectors at the bottom of the wall. In this report some new analytical models for predicting the design (factored) resistance of CLT walls under lateral loads were developed based on connection properties. These new models were then evaluated for their consistency along with their models that are currently used in North America and in Europe.
Online Access
Free
Resource Link
Less detail

Direct Impact Sound Insulation of Cross Laminate Timber Floors with and without Toppings

https://research.thinkwood.com/en/permalink/catalogue227
Year of Publication
2014
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Zeitler, Berndt
Schoenwald, Stefan
Sabourin, Ivan
Organization
Inter-noise
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
North America
Sound Insulation
Concrete Topping
Interlayer
Conference
Inter-Noise 2014
Research Status
Complete
Notes
November 16-19, 2014, Melbourne, Australia
Summary
Cross Laminated Timber (CLT), which is well suited for construction of tall buildings, is becoming a more popular construction material in North America. However, to ensure comfortable living conditions, sound insulation measures are necessary. The study presented here compares results of direct impact sound insulation of 5- and 7-ply CLT floors covered with different a concrete toppings on various interlayers. Improvements of up to 21dB in Weighted Normalized Impact Sound Pressure Level (Ln,w) were observed using a newly proposed reference floor for CLTs. Furthermore, the improvements of floor coverings on CLT floors are compared to those achieved on other types of construction, such as the reference concrete floor. The improvements of Ln,w tend to be higher on the concrete floors than on the CLT floors tested. These and other findings will be presented.
Online Access
Free
Resource Link
Less detail

Effective Bonding Parameters for Hybrid Cross-Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue1368
Year of Publication
2017
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Author
Larkin, Blake
Organization
Oregon State University
Year of Publication
2017
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Connections
Keywords
North America
Low-Grade
Adhesives
Bond Integrity
Polyurethane
Phenol-Resorcinol Formaldehyde
Lodgepole Pine
Douglas-Fir
Hemlock
Manufacturing
Research Status
Complete
Summary
Cross-laminated timber (CLT) is a massive engineered wood product made of orthogonally bonded layers of solid-sawn lumber, and is intended for roof, floor, or wall applications. Although it was developed in Europe in the early 90s, CLT is relatively new to North America. CLT products must be certified for structural use. First North American product standard stipulating test methods and qualification criteria for benchmark structural properties and adhesive bond integrity in structural CLT is ANSI/APA PRG320-2012. These methods and criteria have been adapted from existing laminated timber products (glulam), sometimes disregarding substantial differences between parallel laminates and CLT, in which layers are perpendicular to each other. From the point of view of long term sustainability of the CLT industry in North America, the critical questions are: 1. Is it possible to use low-grade timber harvested in the Pacific Northwest region in CLT products without compromising critical engineering parameters? Utilization of low- grade lumber, which is typically under-valued, in value-added engineered products should reduce the pressure on the high end structural lumber supply and may also provide a substantial outlet for lower-grade lumber timber species, including beetle-killed pine (BKP) harvested in the affected areas. 2. Can alternative adhesive systems, currently used in related engineered wood products and manufactured by domestic industry, be successfully used in CLT production? This is an important question, and is related to the fact that polyurethane (PUR) is the primary adhesive currently used by CLT manufacturing industry, and is supplied worldwide by a single Europe-based company. This adhesive is optimized for the species commonly used in CLT products to-date. ANSI/APA PRG320-2012 standard allows alternative adhesive types (PRF and EPI are specifically named), but to-date, only one alternative (MUF) has been used in commercial products. The objective of this project is to determine effective adhesive systems and bonding pressures for the hybrid cross-laminated timber (CLT) combinations. A secondary objective is to evaluate the testing methods prescribed in PRG 320-2012 for cross-laminated bond integrity. Integrity of hybrid CLT layups was evaluated on small specimens derived from CLT billets fabricated in-house using test procedures and qualification criteria specified in ANSI/APA PRG 320-2012 section 8.2.3. Test results were compared to prescribed qualification criteria. The Hybrid CLT combinations for this study include both structural grade lumber and low-grade lumber. For a reference species, lodgepole pine was selected, since it is a member of the US-SPF group closely related to the European species commonly used for CLT construction. The structural-grade, local species will be represented by Douglas-fir, while the low-grade species will be represented by low-grade lodgepole Pine, Douglas-fir, and Western Hemlock. The two adhesive systems investigated were 1) polyurethane-based PUR (currently the most common adhesive used by the CLT industry), which will serve as a reference system, and 2) phenol-resorcinol formaldehyde (PRF), which will represent a potential domestic alternative. PRF was chosen because it is a cold setting adhesive commonly used by the engineered wood products industry in North America; however, no CLT manufacturers utilize this adhesive system. The variables included species combinations (6), adhesive types (2), and clamping pressures (3), with repetition of 9 specimens per combination coming from at least three different CLT billets. The specimen’s bond integrity was assessed by the qualification panel requirements in PRG 320-2012 section 8.2. The qualification tests are block shear and cyclic delamination. A combination must pass both of the test requirements to qualify. The results of the study show that, of the 36 combinations, six failed the block shear test requirements and twenty-five failed the delamination test requirements. The 10 variable combinations that passed both requirements were DDL10F, DDL40F, DPL40F, PPH10F, PPH69F, PPH10U, PPH40U, PPL10U, PPL69U, and PHL69U. Initial inspection of test results show that no single variable that seems to make a significant impact on the bond integrity. It did reveal that no combinations with the use of Douglas-fir as a face material and PUR as an adhesive met the requirement, and only one combination with western hemlock as a core material met the requirements. It is evident that the delamination test was the major restriction on whether or not a combination passes the bond qualification. We believe that the adaption of a delamination test standard designed for layers with parallel grains makes the passing requirement too strict for an orthogonally bonded product. In conclusion, there were 10 combinations that passed both bond integrity test requirements. It was unclear whether the species and/or grade combination, adhesive system, or clamping pressure made the biggest impact on the bond integrity. Relative to the reference adhesive (PUR), and species combination (lodgepole pine), the hybrid panels performed similarly and showed that certain species and/or grade combinations could pass the qualification requirements for specific requirements. The knowledge gained by this screening study will allow further qualification testing of the passing combinations per PRG320-2012. This also has the potential to supply the CLT manufacturing community with greater flexibility of manufacturing techniques and materials, as well as offer value to underutilized lumber.
Online Access
Free
Resource Link
Less detail

The Evaluation of Panel Bond Quality and Durability of Hem-Fir Cross-Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue1377
Year of Publication
2018
Material
CLT (Cross-Laminated Timber)
Author
Wang, Brad
Wei, Peixing
Gao, Zizhen
Dai, Chunping
Publisher
Springer Berlin Heidelberg
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Keywords
North America
Manufacturing
Hem-Fir
Bond Quality
Durability
Delamination Tests
Block Shear Tests
One-Component Polyurethane
Emulsion Polymer Isocyanate
Applied Pressure
Wood Failure Percentage
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
To better use the second-growth wood resources in value-added applications, this work addressed the manufacturing aspects of cross-laminated timber (CLT) products from western hemlock (Tsuga heterophylla (Raf.) Sarg) and amabilis fir (Abies amabilis (Dougl.) Forbes) (or hem-fir) harvested from coastal British Columbia, Canada. Small CLT billets (nominal 610 mm×610 mm) were made to examine CLT bond quality and durability through block shear and delamination tests. Two types of adhesives, single-component polyurethane (PUR) and emulsion polymer isocyanate (EPI) and two critical applied pressure parameters (0.28 and 0.83 MPa) were adopted to manufacture hem-fir CLT. It was found that the adhesive type and applied pressure significantly affected wood failure percentage (WFP) and delamination of hem-fir CLT. When PUR adhesive was used, CLT made at 0.83 MPa pressure yielded significantly higher WFP and lower delamination than that made at 0.28 MPa pressure. The results demonstrated that despite the fact that hem-fir lumber is not particularly specified in the current North American CLT standard, it could be used for manufacturing CLT with the required panel bond quality.
Online Access
Free
Resource Link
Less detail

Fire Code Development - A Literature Review of North American and Chinese Fire Regulations Related to Wood Frame Buildings

https://research.thinkwood.com/en/permalink/catalogue358
Year of Publication
2014
Topic
Fire
Market and Adoption
Material
Light Frame (Lumber+Panels)
Application
Wood Building Systems
Author
Dagenais, Christian
Peng, Lei
Organization
FPInnovations
Year of Publication
2014
Format
Report
Material
Light Frame (Lumber+Panels)
Application
Wood Building Systems
Topic
Fire
Market and Adoption
Keywords
Multi-Storey
North America
China
Fire Safety
Research Status
Complete
Summary
It can be observed from this review that most fire safety provisions are similar in nature, whether the Chinese, Canadian or American provisions are applied. However, the Chinese code seems to be slightly more restrictive than the North American building codes with respect to wood-use allowances.
Online Access
Free
Resource Link
Less detail

22 records – page 1 of 3.