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Increasing Mass Timber Consumption in the U.S. and Sustainable Timber Supply

https://research.thinkwood.com/en/permalink/catalogue2888
Year of Publication
2022
Topic
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Comnick, Jeff
Rogers, Luke
Wheiler, Kent
Organization
University of Washington
Editor
Lauteri, Marco
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Market and Adoption
Keywords
Mass Timber
Embodied Carbon
Sustainable Timber Supply
Forest Inventory
Reforestation
Research Status
Complete
Series
Sustainability
Summary
Mass timber products are growing in popularity as a substitute for steel and concrete, reducing embodied carbon in the built environment. This trend has raised questions about the sustainability of the U.S. timber supply. Our research addresses concerns that rising demand for mass timber products may result in unsustainable levels of harvesting in coniferous forests in the United States. Using U.S. Department of Agriculture U.S. Forest Service Forest Inventory and Analysis (FIA) data, incremental U.S. softwood (coniferous) timber harvests were projected to supply a high-volume estimate of mass timber and dimensional lumber consumption in 2035. Growth in reserve forests and riparian zones was excluded, and low confidence intervals were used for timber growth estimates, compared with high confidence intervals for harvest and consumption estimates. Results were considered for the U.S. in total and by three geographic regions (North, South, and West). In total, forest inventory growth in America exceeds timber harvests including incremental mass timber volumes. Even the most optimistic projections of mass timber growth will not exceed the lowest expected annual increases in the nation’s harvestable coniferous timber inventory.
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Large-scale compartment fires to develop a self-extinction design framework for mass timber—Part 1: Literature review and methodology

https://research.thinkwood.com/en/permalink/catalogue2911
Year of Publication
2022
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Xu, Hangyu
Pope, Ian
Gupta, Vinny
Cadena, Jaime
Carrascal, Jeronimo
Lange, David
McLaggan, Martyn
Mendez, Julian
Osorio, Andrés
Solarte, Angela
Soriguer, Diana
Torero, Jose
Wiesner, Felix
Zaben, Abdulrahman
Hidalgo, Juan
Organization
The University of Queesland
University of College London
The University of Edinburgh
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Fire
Keywords
Performance-based Design
Compartment Fires
Heat Transfer
Pretection of Wood
Large-scale
Mass Timber
Research Status
Complete
Series
Fire Safety Journal
Summary
Fire safety remains a major challenge for engineered timber buildings. Their combustible nature challenges the design principles of compartmentation and structural integrity beyond burnout, which are inherent to the fire resistance framework. Therefore, self-extinction is critical for the fire-safe design of timber buildings. This paper is the first of a three-part series that seeks to establish the fundamental principles underpinning a design framework for self-extinction of engineered timber. The paper comprises: a literature review introducing the body of work developed at material and compartment scales; and the design of a large-scale testing methodology which isolates the fundamental phenomena to enable the development and validation of the required design framework. Research at the material scale has consolidated engineering principles to quantify self-extinction using external heat flux as a surrogate of the critical mass loss rate, and mass transfer or Damköhler numbers. At the compartment scale, further interdependent, complex phenomena influencing self-extinction occurrence have been demonstrated. Time-dependent phenomena include encapsulation failure, fall-off of charred lamellae and the burning of the movable fuel load, while thermal feedback is time-independent. The design of the testing methodology is described in reference to these fundamental phenomena.
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Comparative life cycle assessment of cross laminated timber building and concrete building with special focus on biogenic carbon

https://research.thinkwood.com/en/permalink/catalogue2913
Year of Publication
2022
Topic
Environmental Impact
Energy Performance
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Andersen, Julie
Rasmussen, Nana
Ryberg, Morten
Organization
Technical University of Denmark
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Environmental Impact
Energy Performance
Keywords
Life-Cycle Assessment
Biogenic Carbon
Forest Transformation
Research Status
Complete
Series
Energy and Buildings
Summary
This study conducted a consequential Life Cycle Assessment (LCA) on two similar mid-rise apartment buildings applying either concrete or cross laminated timber (CLT) as the main structural material. The study further investigated inclusion of biogenic carbon and how this affects environmental impacts related to Global warming. Thus, two assessment scenarios were applied: A Base scenario, without accounting for biogenic carbon and a Biogenic carbon scenario that include a GWPbio factor to account for the use of biogenic carbon. The CLT building had the lowest impact score in 11 of 18 impact categories including Global warming. Operational energy use was the main contributor to the total impact with some variation across impact scores, but closely followed by impacts embodied in materials (incl. End-of-Life). An evaluation of the potential forest transformations required for fulfilling future projections for new building construction in 2060 showed that about 3% of current global forest area would be needed. This share was essentially independent of the selected building material as the main driver for forest transformation was found to be energy use during building operation. Thus, focus should primarily be on reducing deforestation related to energy generation rather than deforestation from production of building materials.
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What Is the Impact of Mass Timber Utilization on Climate and Forests?

https://research.thinkwood.com/en/permalink/catalogue2921
Year of Publication
2022
Topic
Environmental Impact
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Pasternack, Rachel
Wishnie, Mark
Clarke, Caitlin
Wang, Yangyang
Belair, Ethan
Marshall, Steve
Gu, Hongmei
Nepal, Prakash
NDolezal, Franz
Lomax, Guy
Johnston, Craig
Felmer, Gabriel
Morales-Vera, Rodrigo
Puettmann, Maureen
Huevel, Robyn
Organization
USDA Forest Service Forest Products Laboratory
University of Exeter
Universidad de Chile
Universidad Católica del Maule
Editor
Ganguly, Indroneil
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Environmental Impact
Keywords
Life-Cycle Assessment
Climate Change
Embodied Carbon
Carbon Storage
Research Status
Complete
Series
Sustainability
Summary
As the need to address climate change grows more urgent, policymakers, businesses, and others are seeking innovative approaches to remove carbon dioxide emissions from the atmosphere and decarbonize hard-to-abate sectors. Forests can play a role in reducing atmospheric carbon. However, there is disagreement over whether forests are most effective in reducing carbon emissions when left alone versus managed for sustainable harvesting and wood product production. Cross-laminated timber is at the forefront of the mass timber movement, which is enabling designers, engineers, and other stakeholders to build taller wood buildings. Several recent studies have shown that substituting mass timber for steel and concrete in mid-rise buildings can reduce the emissions associated with manufacturing, transporting, and installing building materials by 13%-26.5%. However, the prospect of increased utilization of wood products as a climate solution also raises questions about the impact of increased demand for wood on forest carbon stocks, on forest condition, and on the provision of the many other critical social and environmental benefits that healthy forests can provide. A holistic assessment of the total climate impact of forest product demand across product substitution, carbon storage in materials, current and future forest carbon stock, and forest area and condition is challenging, but it is important to understand the impact of increased mass timber utilization on forests and climate, and therefore also on which safeguards might be necessary to ensure positive outcomes. To thus assess the potential impacts, both positive and negative, of greater mass timber utilization on forests ecosystems and emissions associated with the built environment, The Nature Conservancy (TNC) initiated a global mass timber impact assessment (GMTIA), a five-part, highly collaborative research program focused on understanding the potential benefits and risks of increased demand for mass timber products on forests and identifying appropriate safeguards to ensure positive outcomes.
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A Lifecycle Assessment of a Low-Energy Mass-Timber Building and Mainstream Concrete Alternative in Central Chile

https://research.thinkwood.com/en/permalink/catalogue2922
Year of Publication
2022
Topic
Environmental Impact
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Felmer, Gabriel
Morales-Vera, Rodrigo
Astroza, Rodrigo
González, Ignacio
Puettmann, Maureen
Wishnie, Mark
Organization
Universidad de Chile
Universidad Católica del Maule
Universidad Bernardo O’Higgins
Universidad de los Andes
Editor
Caggiano, Antonio
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Environmental Impact
Keywords
Life-Cycle Assessment
Mid-Rise
Carbon Storage
Passive Zero Carbon Housing
Research Status
Complete
Series
Sustainability
Summary
While high-rise mass-timber construction is booming worldwide as a more sustainable alternative to mainstream cement and steel, in South America, there are still many gaps to overcome regarding sourcing, design, and environmental performance. The aim of this study was to assess the carbon emission footprint of using mass-timber products to build a mid-rise low-energy residential building in central Chile (CCL). The design presented at a solar decathlon contest in Santiago was assessed through lifecycle analysis (LCA) and compared to an equivalent mainstream concrete building. Greenhouse gas emissions, expressed as global warming potential (GWP), from cradle-to-usage over a 50-year life span, were lower for the timber design, with 131 kg CO2 eq/m2 of floor area (compared to 353 kg CO2 eq/m2) and a biogenic carbon storage of 447 tons of CO2 eq/m2 based on sustainable forestry practices. From cradle-to-construction, the embodied emissions of the mass-timber building were 42% lower (101 kg CO2 eq/m2) than those of the equivalent concrete building (167 kg CO2 eq/m2). The embodied energy of the mass-timber building was 37% higher than that of its equivalent concrete building and its envelope design helped reduce space-conditioning emissions by as much as 83%, from 187 kg CO2 eq/m2 as estimated for the equivalent concrete building to 31 kg CO2 eq/m2 50-yr. Overall, provided that further efforts are made to address residual energy end-uses and end-of-life waste management options, the use of mass-timber products offers a promising potential in CCL for delivering zero carbon residential multistory buildings.
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Out-of-Plane Tensile Properties of Cross Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue2940
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Brandner, Reinhard
Jantscher, Lukas
Organization
Graz University of Technology
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Keywords
Out-Of-Plane Tension
Size Effect
System Effects
Modulus of Elasticity
Strength
Equicorrelation
Research Status
Complete
Series
Buildings
Summary
A systematic investigation is still lacking for tension out-of-plane in cross laminated timber (CLT), as a planar timber construction product. The objectives of the present study are the determination of the tensile properties of CLT made of Norway spruce, the identification of essential product-specific influencing parameters and a comparative analysis with glulam. For this purpose, seven test series were defined, which allowed the determination of the tensile properties on board segments and thereof produced glulam and CLT specimens by varying the number of layers, layer orientation and number of elements within a layer. The orthogonal laminated structure of CLT led to between 50% and 70% higher tensile properties out-of-plane, which is explained by the different stress distribution compared to glulam; the regulation of 30% higher properties than for glulam is suggested. In addition, the lognormal distribution turned out to be a more representative distribution model for characterizing the tensile strength out-of-plane than the Weibull distribution. This was also confirmed with regard to the investigated serial and parallel system effects, in which a clearly more homogeneous behavior was found in CLT compared to glulam, which in turn can be attributed again to the different stress distributions.
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Rolling Shear Properties of Cross-Laminated Timber Made from Australian Plantation Eucalyptus nitens under Planar Shear Test

https://research.thinkwood.com/en/permalink/catalogue2945
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Ettelaei, Azin
Taoum, Assaad
Shanks, Jon
Nolan, Gregory
Organization
University of Tasmania
Editor
Oliveira, Diego
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Keywords
Rolling Shear
Hardwood Plantation
Planar Shear Tests
Structural Properties
Research Status
Complete
Series
Forests
Summary
With the increasing availability of fast-growing Eucalyptus plantation logs in Australia in recent years, the timber manufacturing sector has become interested in discovering the opportunities of producing value-added timber products from this resource. Cross-laminated timber (CLT) could be a potential sustainable product recovered from this resource and supply material for commercial buildings. Shear of the inner cross-laminates, known as rolling shear, is one of the governing factors in serviceability and limit state design for this product under out-of-plane loading. This study evaluated the rolling shear (RS) properties of CLT with heterogonous layup configurations using different structural grade Eucalyptus nitens (E. nitens) timber under the planar shear test. Based on the results, Gr and tr values were shown to be significantly correlated with the density of the CLT panel. There was also a positive correlation between the RS modulus and MOR of the CLT panel. The specimens with high MOE in the top and bottom layers indicated the highest tr and Fmax values. This indicated that using high-grade boards in the top and bottom lamellae plays an important role in increasing the RS strength, whereas using them in the cross-layer has a positive contribution in increasing shear modulus. The maximum observed RS strength and modulus ranged from 2.8–3.4 MPa and 54.3–67.9 MPa, respectively, exceeding the RS characteristic values of the resource. The results obtained in this study were comparable to those recommended in European standards for softwood CLT, demonstrating the potential use for eucalypt timber boards in CLT production. This paper provides an important insight into supporting the potential engineering applications of CLT panel products fabricated with eucalypt plantation.
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Analysis and Tests of Lateral Resistance of Bolted and Screwed Connections of CLT

https://research.thinkwood.com/en/permalink/catalogue2956
Year of Publication
2022
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Huo, Liangliang
Zhu, Enchun
Niu, Shuang
Wu, Guofang
Organization
Harbin Institute of Technology
China Academy of Forestry
Editor
Ozarska, Barbara
Monaco, Angela
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Connections
Keywords
Lateral Resistance
European Yield Model
Bolt Connection
Screw Connectors
Emdedment Stress
Research Status
Complete
Series
Forests
Summary
The lateral resistance of dowel-type connections with CLT is related to its lay-up, species of the laminations and even the manufacture method. Treating the CLT as homogeneous material, current methods develop new equations through test results or make use of the existing equations for the embedment strength already used in design codes; thus, the lateral resistance of dowel-type connections of CLT can be calculated. This kind of approach does not take the embedment stress distribution into account, which may lead to inaccuracy in predicting the lateral resistance and yield mode of the dowel-type connections in CLT. In this study, tests of the bolted connections and the screwed connections of CLT were conducted by considering the effects of the orientation of the laminations, the thickness of the connected members, the fastener diameter and strength of the materials. The material properties including yield strength of the fasteners and embedment strength of the CLT laminations were also tested. Using analysis of the dowel-type connections of CLT by introducing the equivalent embedment stress distribution, equations for the lateral resistance of the connections based on the European Yield Model were developed. The predicted lateral resistance and yield modes were in good agreement with the test results; the correctness and the feasibility of the equations were thus validated.
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Large-Scale Enclosure Fire Experiments Adopting CLT Slabs with Different Types of Polyurethane Adhesives: Genesis and Preliminary Findings

https://research.thinkwood.com/en/permalink/catalogue2963
Year of Publication
2022
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Hopkin, Danny
Wegrzynski, Wojciech
Spearpoint, Michael
Fu, Ian
Krenn, Harald
Sleik, Tim
Gorska, Carmen
Stapf, Gordian
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Fire
Keywords
Adhesive
Bond-line Failure
Char Fall-off
Polyurethane
Auto-Extinction
Flame Spread
Research Status
Complete
Series
Fire
Summary
This paper provides understanding of the fire performance of exposed cross-laminated-timber (CLT) in large enclosures. An office-type configuration has been represented by a 3.75 by 7.6 by 2.4 m high enclosure constructed of non-combustible blockwork walls, with a large opening on one long face. Three experiments are described in which propane-fuelled burners created a line fire that impinged on different ceiling types. The first experiment had a non-combustible ceiling lining in which the burners were set to provide flames that extended approximately halfway along the underside of the ceiling. Two further experiments used exposed 160 mm thick (40-20-40-20-40 mm) loaded CLT panels with a standard polyurethane adhesive between lamella in one experiment and a modified polyurethane adhesive in the other. Measurements included radiative heat flux to the ceiling and the floor, temperatures within the depth of the CLT and the mass loss of the panels. Results show the initial peak rate of heat release with the exposed CLT was up to three times greater when compared with the non-combustible lining. As char formed, this stabilised at approximately one and a half times that of the non-combustible lining. Premature char fall-off (due to bond-line failure) was observed close to the burners in the CLT using standard polyurethane adhesive. However, both exposed CLT ceiling experiments underwent auto-extinction of flaming combustion once the burners were switched off.
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Performance-Based Design of Tall Timber Buildings Under Earthquake and Wind Multi-Hazard Loads: Past, Present, and Future

https://research.thinkwood.com/en/permalink/catalogue2970
Year of Publication
2022
Topic
Design and Systems
Seismic
Application
Wood Building Systems
Author
Tesfamariam, Solomon
Organization
University of British Columbia
Editor
Kopp, Gregory
Publisher
Frontiers
Year of Publication
2022
Format
Journal Article
Application
Wood Building Systems
Topic
Design and Systems
Seismic
Keywords
Multi-hazard Design
Tall-timber building
Damping
Multi-fidelity Models
Energy Dissipation Devices
Optimization
Research Status
Complete
Series
Frontiers in Built Environment
Summary
The rapid growth of the urban population and associated environmental concerns are challenging city planners and developers to consider sustainable and cost-efficient building systems. Timber-based buildings, such as sustainable systems, are increasingly used. The timber buildings, however, being lighter and flexible, can be vulnerable to earthquakes and wind loads. This paper gives a state-of-the-art review on performance-based design (PBD) considerations and future direction for timber and timber-based hybrid buildings. The PBD review covered both earthquake and wind loads and multi-hazard design considerations. The review also provided 1) current practice and future direction in consideration of hazard, response, and loss assessment within the multi-hazard PBD, 2) damping and energy dissipation devices, 3) optimization under uncertainty, and 4) future of surrogate and multi-fidelity modeling in PBD.
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700 records – page 1 of 70.