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A Holistic Approach for Industrializing Timber Construction

https://research.thinkwood.com/en/permalink/catalogue2378
Year of Publication
2019
Topic
Site Construction Management
Design and Systems
Material
Timber (unspecified)
Application
Wood Building Systems
Author
Santana-Sosa, Aída
Fadai, Alireza
Year of Publication
2019
Country of Publication
Austria
Format
Conference Paper
Material
Timber (unspecified)
Application
Wood Building Systems
Topic
Site Construction Management
Design and Systems
Keywords
Prefabrication
Off-site Construction
BIM
Mass Timber
Construction
Carbon
Language
English
Conference
Sustainable Built Environment D-A-CH Conference
Research Status
Complete
Summary
Many strategies have been investigated seeking for efficiency in construction sector, since it has been pointed out as the largest consumer of raw materials worldwide and responsible of about 1/3 of the global CO2 emissions. While operational carbon has been strongly reduced due to building regulations, embodied carbon is becoming dominating. Resources and processes involved from material extraction to building erection should be carefully optimized aiming to reduce the emissions from the cradle to service. New advancements in timber engineering have shown the capabilities of this renewable and CO2 neutral material in multi-storey buildings. Since their erection is based on prefabrication, an accurate construction management is eased where variations and waste are sensible to be minimized. Through this paper, the factors constraining the use of wood as main material for multi-storey buildings will be explored and the potential benefits of using Lean Construction principles in the timber industry are highlighted aiming to achieve a standardized workflow from design to execution. Hence, a holistic approach towards industrialization is proposed from an integrated BIM model, through an optimized supply chain of off-site production, and to a precise aligned scheduled on-site assembly.
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A Comparative Life Cycle Assessment Approach of Two Innovative Long Span Timber floors with its Reinforced Concrete Equivalent in an Australian Context

https://research.thinkwood.com/en/permalink/catalogue2375
Year of Publication
2015
Topic
Environmental Impact
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Wood Building Systems
Author
Basaglia, Bella
Lewis Kirsten
Shrestha, Rijun
Crews, Keith
Publisher
School of Civial Engineering, The University of Queensland
Year of Publication
2015
Country of Publication
Australia
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Wood Building Systems
Topic
Environmental Impact
Keywords
Sustainable Materials
LCA
Life-Cycle Assessment
Mid-Rise
Concrete
Language
English
Conference
International Conference on Performance-based and Life-cycle Structural Engineering
Research Status
Complete
Online Access
Free
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An Application of the CEN/TC350 Standards to an Energy and Carbon LCA of Timber Used in Construction, and the Effect of End-of-Life Scenarios

https://research.thinkwood.com/en/permalink/catalogue2376
Year of Publication
2013
Topic
Energy Performance
Material
CLT (Cross-Laminated Timber)
Timber (unspecified)
Application
Wood Building Systems
General Application
Author
Symons, Katie
Moncaster, Alice
Symons, Digby
Year of Publication
2013
Country of Publication
United Kingdom
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Timber (unspecified)
Application
Wood Building Systems
General Application
Topic
Energy Performance
Keywords
Embodied Carbon
Life-Cycle Assessment
Built Environment
End of Life
LCA
Europe
Language
English
Conference
Australian Life Cycle Assessment Society conference
Research Status
Complete
Summary
The use of timber construction products and their environmental impacts is growing in Europe. This paper examines the LCA approach adopted in the European CEN/TC350 standards, which are expected to improve the comparability and availability of Environmental Product Declarations (EPDs). The embodied energy and carbon (EE and EC) of timber products is discussed quantitatively, with a case study of the Forte building illustrating the significance of End-of-Life (EoL) impacts. The relative importance of timber in the context of all construction materials is analysed using a new LCA tool, Butterfly. The tool calculates EE and EC at each life cycle stage, and results show that timber products are likely to account for the bulk of the EoL impacts for a typical UK domestic building.
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The Environmental Impact of Reused CLT Panels: Study of a Single-Storey Commercial Building In Japan

https://research.thinkwood.com/en/permalink/catalogue2377
Year of Publication
2018
Topic
Energy Performance
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Author
Passarelli, Rafael
Year of Publication
2018
Country of Publication
Korea
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Topic
Energy Performance
Design and Systems
Keywords
Global Warming Potential
Commercial
Panels
Carbon
Design for Reuse
Timber Cascade
Life-Cycle Assessment
LCA
Construction
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
The study investigates the environmental benefits of reusing Cross Laminated Timber (CLT) panels. The Global Warming Potential (GWP) of a single-stored Coffee shop built in 2016 in Kobe city was calculated, considering different CLT reuse ratios, forest land-use and material substitution possibilities. The results showed that as the rate of reused CLT panel increases the total GWP decreases. Moreover, in all cases, the option with smallest GWP is when the surplus wood is used for carbon storage in the forest, revealing the importance of a growing forest for increasing the environmental benefits of timber utilisation. The results suggest the systematic reuse of CLT panels offers a possibility to increase the carbon stock of Japanese Cedar plantation forests and further mitigate the environmental impact of construction.
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Identifying Mass Timber Research Priorities, Barriers to Adoption and Engineering, Procurement and Construction Challenges In Canada

https://research.thinkwood.com/en/permalink/catalogue2372
Year of Publication
2020
Topic
Market and Adoption
Material
Timber (unspecified)
Application
Wood Building Systems
Author
Syed, Taha
Publisher
University of Toronto
Year of Publication
2020
Country of Publication
Canada
Format
Thesis
Material
Timber (unspecified)
Application
Wood Building Systems
Topic
Market and Adoption
Keywords
Mass Timber
Barriers
Research Priorities
Challenges
Construction
Engineering
Procurement
Language
English
Research Status
Complete
Summary
Mass timber construction in Canada is in the spotlight and emerging as a sustainable building system that offers an opportunity to optimize the value of every tree harvested and to revitalize a declining forest industry, while providing climate mitigation solutions. Little research has been conducted, however, to identify the mass timber research priorities of end users, barriers to adoption and engineering, procurement and construction challenges in Canada. This study helps bridge these gaps. The study also created an interactive, three-dimensional GIS map displaying mass timber projects across North America, as an attempt to offer a helpful tool to practitioners, researchers and students, and fill a gap in existing knowledge sharing. The study findings, based on a web-based survey of mass timber end users, suggest the need for more research on (a) total project cost comparisons with concrete and steel, (b) hybrid systems and (c) mass timber building construction methods and guidelines. The most important barriers for successful adoption are (a) misconceptions about mass timber with respect to fire and building longevity, (b) high and uncertain insurance premiums, (c) higher cost of mass timber products compared to concrete and steel, and (d) resistance to changing from concrete and steel. In terms of challenges: (a) building code compliance and regulations, (b) design permits and approvals, and (c) insufficient design experts in the market are rated by study participants as the most pressing “engineering” challenge. The top procurement challenges are (a) too few manufactures and suppliers, (b) long distance transportation, and (c) supply and demand gaps. The most important construction challenges are (a) inadequate skilled workforce, (b) inadequate specialized subcontractors, and (c) excessive moisture exposure during construction.
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Design Options for Three- and Four-Storey Wood School Buildings in British Columbia

https://research.thinkwood.com/en/permalink/catalogue2373
Year of Publication
2019
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
NLT (Nail-Laminated Timber)
DLT (Dowel Laminated Timber)
Glulam (Glue-Laminated Timber)
Other Materials
Timber (unspecified)
Application
Wood Building Systems
General Application
Author
Bevilacqua, Nick
Dickof, Carla
Wolfe, Ray
Gan, Wei-Jie
Embury-Williams, Lynn
Organization
Fast + Epp
Wood Works! BC
Thinkspace
Year of Publication
2019
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
NLT (Nail-Laminated Timber)
DLT (Dowel Laminated Timber)
Glulam (Glue-Laminated Timber)
Other Materials
Timber (unspecified)
Application
Wood Building Systems
General Application
Topic
Design and Systems
Keywords
Construction
Education
School Buildings
Mass Timber
Multi-Storey
Building Code
Fire Protection
Language
English
Research Status
Complete
Summary
This study illustrates the range of possible wood construction approaches for school buildings that are up to four storeys in height. As land values continue to rise, particularly in higher-density urban environments, schools with smaller footprints will become increasingly more necessary to satisfy enrollment demands. There are currently a number of planned new school projects throughout British Columbia that anticipate requiring either three-or four-storey buildings, and it is forecasted that the demand for school buildings of this size will continue to rise. This study is closely related to the report Risk Analysis and Alternative Solution for Three- and Four-Storey Schools of Mass Timber and/or Wood-Frame Construction prepared by GHL Consultants, which explores the building code related considerations of wood construction for school buildings that are up to four storeys in height. Though wood construction offers a viable structural material option for these buildings, the British Columbia Building Code (BCBC 2018) currently limits schools comprised of wood construction to a maximum of two storeys, while also imposing limits on the overall floor area. As such, the reader is referred to the GHL report for further information regarding building code compliance (with a particular emphasis on fire protection) for wood school buildings.
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Risk Analysis and Alternative Solution for Three- and Four-Storey Schools of Mass Timber and/or Wood-Frame Construction

https://research.thinkwood.com/en/permalink/catalogue2374
Year of Publication
2019
Topic
Design and Systems
Market and Adoption
Fire
Material
Timber (unspecified)
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Other Materials
Application
Wood Building Systems
General Application
Organization
GHL Consultants Ltd.
Year of Publication
2019
Country of Publication
Canada
Format
Report
Material
Timber (unspecified)
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Other Materials
Application
Wood Building Systems
General Application
Topic
Design and Systems
Market and Adoption
Fire
Keywords
Building Code
Education
School Buildings
Multi-Storey
Fire Test
Fire Safety
Technical Risk
Process Risk
Mass Timber
Language
English
Research Status
Complete
Summary
This report explores the building code related considerations of wood construction for school buildings that are up to four storeys in height. Though wood construction offers a viable structural material option for these buildings, the British Columbia Building Code (BCBC 2018) currently limits schools comprised of wood construction to a maximum of two storeys. Three- and four-storey schools and larger floor areas in wood construction require an Alternative Solution. The report identifies key fire safety features offered by combustible construction materials including tested and currently widely available engineered mass timber products, such as glued-laminated timber and cross-laminated timber. A risk analysis identifies the risk areas defined by the objectives of the British Columbia Building Code (BCBC 2018) and evaluates the level of performance of the Building Code solutions for assembly occupancies vis-à-vis the level of performance offered by the proposed schools up to four storeys in building height. As land values continue to rise, particularly in higher-density urban environments, schools with smaller footprints will become increasingly more necessary to satisfy enrollment demands. There are currently a number of planned new school projects throughout British Columbia that anticipate requiring either three-or four-storey buildings, and it is forecasted that the demand for school buildings of this size will continue to rise. This report is closely related to the study Design Options for Three-and Four-Storey Wood School Buildings in British Columbia, which illustrates the range of possible timber construction approaches for school buildings that are up to four storeys in height.
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Evaluation of the Bonding Quality of E. grandis Cross-Laminated Timber Made With a One-Component Polyurethane Adhesive

https://research.thinkwood.com/en/permalink/catalogue2369
Year of Publication
2018
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Author
Dugmore, Michael
Publisher
Stellenbosch University
Year of Publication
2018
Country of Publication
South Africa
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Topic
Design and Systems
Keywords
Polyurethane
Panels
Bond Performance
Bond Quality
Durability Assessment
Language
English
Research Status
Complete
Summary
Eucalyptus grandis is South Africa‘s most important commercial hardwood species. The availability of E. grandis and its fast growth rate creates the opportunity to explore its uses further. Cross-laminated timber (CLT) is a prefabricated multilayer engineered panel product made of at least three layers, with the grain direction of some or all of the consecutive layers orthogonally orientated. In order to add value to E. grandis, reduce the export of low-cost chips, increase the profit margins of local plantation owners and create jobs, the development of E. grandis CLT in South Africa may be an option. There is concern among some researchers that the bonding quality evaluation tests proposed by CLT standards have been developed for glulam and are too severe for CLT. These researchers proposed that further analysis and possibly even revision of the test methods should be considered. There is also a need to evaluate the mechanical properties of CLT panels made of E. grandis to completely understand the structural performance of these panels, including their bond quality and durability, and therefore be able to rely on E. grandis CLT as a construction material. The objectives of this study were: . To evaluate the face-bonding quality of CLT panels from E. grandis timber bonded with a one component polyurethane resin; . To determine the influence of material and processing parameters on the face-bonding quality of CLT manufactured from E. grandis timber bonded with a one component polyurethane resin; . To analyse different testing methods for evaluating the face-bonding quality of CLT. The design for this experiment consisted of eight groups with different combinations of parameters for density, grooves and pressure per group. Four different testing methods were used to evaluate the face-bonding quality of CLT panels from E. grandis and to determine the effect of parameters on face-bonding quality: A delamination test on 100 x 100 mm block specimens (Test A), a shear test on 40 x 40 mm specimens (Test B), a shear test on 40 x 40 mm specimens with grain direction 45° to load direction (Test C) and a combined delamination and shear test on 70 x 70 mm specimens with grain direction 45° to load direction (Test D). Results of the statistical analysis indicated that E. grandis CLT made with 1C-PUR adhesive can obtain excellent face-bonding quality using a clamping pressure of 0.7 MPa and with no stress relief grooves present. All samples passed the shear test (Test B) which is the reference test method proposed by EN 16351 (2015). It was found that a strength component and durability component will be an advantage when testing the bond quality of CLT. Shear tests at 45° to the load direction did not completely eliminate the rolling shear effect. The combined delamination and shear test (Test D), seems to have potential as a good test for bond quality since it is a combination of a durability and shear strength test. There are still questions about the relative advantages of specific test methods for bond quality, especially on the effect of rolling shear. Further work should focus on this aspect and the use of stress models might be a way of gaining further insights.
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Design of Controlled Rocking Heavy Timber Walls For Low-To-Moderate Seismic Hazard Regions

https://research.thinkwood.com/en/permalink/catalogue2370
Year of Publication
2016
Topic
Seismic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Kovacs, Michael
Publisher
McMaster University
Year of Publication
2016
Country of Publication
Canada
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Seismic
Design and Systems
Keywords
Controlled Rocking
Heavy Timber
Low-to-Moderate Seismic Hazard
Post-Tensioned Timber
Force-Based Design
Non-Linear Time-History Analysis
Language
English
Research Status
Complete
Summary
The controlled rocking heavy timber wall (CRHTW) is a high-performance structural solution that was first developed in New Zealand, mainly considering Laminated Veneer Lumber (LVL), to resist high seismic loads without sustaining structural damage. The wall responds in bending and shear to small lateral loads, and it rocks on its foundation in response to large seismic loads. In previous studies, rocking has been controlled by both energy dissipation elements and post-tensioning, and the latter returns the wall to its original position after a seismic event. The controlled rocking response avoids the need for structural repair after an earthquake, allowing for more rapid return to occupancy than in conventional structures. Whereas controlled rocking walls with supplemental energy dissipation have been studied before using LVL, this thesis proposes an adapted CRHTW in which the design and construction cost and complexity are reduced for low-to-moderate seismic hazard regions by removing supplemental energy dissipation and using cross-laminated timber (CLT) because of its positive economic and environmental potential in the North American market. Moreover, whereas previous research has focussed on direct displacement-based design procedures for CRHTWs, with limited consideration of force-based design parameters, this thesis focusses on force-based design procedures that are more common in practice. A design and analysis process is outlined for the adapted CRHTW, based on a similar methodology for controlled rocking steel braced frames. The design process includes a new proposal to minimize the design forces while still controlling peak drifts, and it also includes a new proposal for predicting the influence of the higher modes by referring to previous research on the capacity design of controlled rocking steel braced frames. Also, a numerical model is outlined, including both a baseline version and a lower-bound model based on comparison to experimental data. The numerical model is used for non-linear time-history analysis of a prototype design, confirming the expected performance of the adapted CRHTW, and the model is also used for incremental dynamic analyses of three-, six-, and nine-storey prototypes, which show a low probability of collapse.
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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.
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Modeling the Coupling Effect of CLT Connections Under Bi-Axial Loading

https://research.thinkwood.com/en/permalink/catalogue2366
Year of Publication
2019
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Author
Liu, Jingjing
Lam, Frank
Foschi, Ricardo
Li, Minghao
Year of Publication
2019
Country of Publication
United States
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Topic
Connections
Keywords
Coupling Effect
Biaxial loading
Degradation
Modeling
Language
English
Research Status
Complete
Series
Journal of Structural Engineering
Summary
This paper presents the modeling of coupling effect of tension and shear loading on Cross Laminated Timber (CLT) connections using a finite element based algorithm called HYST. The model idealizes the connections as a “Pseudo Nail” - elastoplastic beam elements (the nail) surrounded by compression-only spring elements (steel sheath and wood embedment). A gap size factor and an unloading stiffness degradation index of the spring elements under cyclic loading were integrated into the optimized HYST algorithm to consider the coupling effect. The model was calibrated to compare with 32 configurations of CLT angle bracket and hold-down connections tests: in tension with co-existent constant shear force, and in shear with co-existent tension force. The results showed that the proposed model can fully capture the coupling effect of typical CLT connections, considering strength degradation, unloading and reloading stiffness degradation, and pinching effect. The model provided a useful tool for nailbased timber connections and a mechanism-based explanation to understand the hysteretic behaviour of CLT connections under bi-axial loading.
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Influence of Lamination Aspect Ratios and Test Methods on Rolling Shear Strength Evaluation of Cross Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue2367
Year of Publication
2019
Topic
Design and Systems
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Author
Li, Minghao
Dong, Wenchen
Lim, Hyungsuk
Year of Publication
2019
Country of Publication
United States
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Topic
Design and Systems
Mechanical Properties
Keywords
Rolling Shear Strength
Lamination Aspect Ratio
Short-Span Bending
Numerical Modelling
Douglas-Fir
Radiata Pine
Language
English
Research Status
Complete
Series
Journal of Materials in Civil Engineering
Summary
Rolling shear (RS) strength may govern load carrying capacity of cross laminated timber (CLT) subjected to high out-of-plane loading because high RS stresses may be induced in cross layers and wood typically has low RS strength. This study investigates RS strength properties of none-edge-glued CLT via experimental testing (short-span bending tests and modified planar shear tests) and numerical modelling. CLT specimens with different manufacturing parameters including two timber species (New Zealand grown Douglas-fir and Radiata pine), three lamination thickness (20 mm, 35 mm, and 45 mm) and various lamination aspect ratios (4.1~9.8) were studied. The lamination aspect ratio was found to have a substantial impact on RS strength of CLT. Higher aspect ratios led to a significant increase of RS strength and an approximately linear relationship could be established. With similar lamination aspect ratios, the Radiata pine CLT had higher RS strength than the Douglas-fir CLT. The two different test methods, however, yielded comparable RS strength assessments. Numerical models were further developed to study the influence of the test configurations and gaps in the cross layers on stress distributions in the cross layers. It was also found the compressive stresses perpendicular to grain in cross layers had negligible influence on the RS strength evaluations.
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Developing a Design Procedure for Cross Laminated Timber Mats

https://research.thinkwood.com/en/permalink/catalogue2368
Year of Publication
2017
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Author
Torra, Ines
Publisher
University of Illinois at Chicago
Year of Publication
2017
Country of Publication
United States
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Topic
Design and Systems
Keywords
Finite Element Analysis
Damage Models
Design Procedure
Language
English
Research Status
Complete
Summary
Cross-laminated Timber (CLT), a new generation of engineered wood product developed initially in Europe, is a relatively innovative building system of interest in the North American construction and is helping to define a new class of timber products known as massive or “mass” timber. This material has been gaining popularity in residential and non-residential applications in several countries due to many advantages it can offer: high dimension stability, high strength and stiffness, high level of prefabrication, fire resistant, cost and energy efficient, renewable and biodegradable, sustainable, and good thermal and sound insulator. However, CLT represents a complicated material whose behavior is difficult to predict in various applications and requires care from the engineers and researchers. Due to the increase of the use of CLT mats for industrial, construction and environmental applications, CLT mats are currently used in industrial applications, this study presents the analysis and behavior of such mats. Three-dimensional non-linear finite element models, using ANSYS, have been created, analyzed and compared with previous experimental work previously performed to validate the models. The model includes detailed modeling, analysis and investigation of the wood material supported by soil. This research shows a non-linear finite element analysis model that can predict CLT behavior. Damage models of CLT is used to determine the failure modes of this material. The analysis results are compared with current industrial practices published guides and highlight the limitations of such procedures. Lastly, a design procedure was developed for the analysis of different configurations such mats.
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Non-Uniformly Distributed Compression Perpendicular to the Grain in Steel-CLT Connections: Experimental and Numerical Analysis of Bearing Capacity and Displacement Behaviour

https://research.thinkwood.com/en/permalink/catalogue2363
Year of Publication
2019
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Author
Ncube, Noah
Sabaa, Stephen
Publisher
Linnaeus University
Year of Publication
2019
Country of Publication
Sweden
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Topic
Connections
Keywords
Compression
Perpendicular to the Grain
Non-Uniformly Distributed
Finite Element
Load Configuration Factor
Steel Connections
Load
Language
English
Research Status
Complete
Summary
Previous studies have mainly focused on the behaviour of timber under uniformly distributed compression perpendicular to the grain (CPG) loads. However, there are many practical applications in which timber is loaded by non-uniformly distributed CPG loads. Different design and test codes like the Eurocode 5 (EC5), DIN 1052:2004, ASTM D143- 94 and EN-408:2010 only account for load configurations where timber is subjected to uniformly distributed loads. For specific uniformly distributed load (UDL) configurations the bearing capacity of timber (solid softwood timber or Glulam) in compression is adapted by using a load configuration factor (kc,90) according to EC5, the European code for design of timber structures. EC5 has no guidelines for cross-laminated timber (CLT) under UDL with the exception of the Austrian National Regulations for EC5. In this work, an experimental and numerical study on the bearing capacity and displacement behaviour of CLT subjected to non-uniformly distributed loading (NuDL) is conducted on eight different load configurations. A steel-CLT connection in which the CLT is partially loaded is used in this study. Finite element modelling, performed using the commercial software Abaqus CAE is used as the numerical simulation of the experimental study and is validated by experimental results. Load configuration factors (kc,90) from experimental results are compared with values from the Swedish CLT handbook (KL-Trähandbok). The outcome of the study shows that load configuration factor for NuDL cases is higher than for UDL cases. Hence, for same load configurations a lower CPG strength is required in NuDL than in UDL. Moreover, numerical results feature overall good congruence with the elastic phase of the experiments and have the potential to augment experiments in further understanding other complex steel-CLT connections
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Design of an Energy-Efficient and Cost-Effective Cross Laminated Timber (CLT) House in Waikuku Beach, New Zealand

https://research.thinkwood.com/en/permalink/catalogue2364
Year of Publication
2016
Topic
Design and Systems
Cost
Energy Performance
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Author
Bournique, Guillaume
Publisher
KTH Royal Institute of Technology
Year of Publication
2016
Country of Publication
Sweden
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Topic
Design and Systems
Cost
Energy Performance
Keywords
Energy Efficiency
Cost-Competitive
Residential
Housing
Energy Consumption
Language
English
Research Status
Complete
Summary
The Canterbury earthquakes in 2010 and 2011 caused significant damage to the Christchurch building stock. However, it is an opportunity to build more comfortable and energy efficient buildings. Previous research suggests a tendency to both under heat and spot heat, meaning that New Zealand dwellings are partly heated and winter indoor temperatures do not always meet the recommendations of the World Health Organization. Those issues are likely to be explained by design deficiency, poor thermal envelope, and limitations of heating systems. In that context, the thesis investigates the feasibility of building an energy efficient and cost-competitive house in Christchurch. Although capital costs for an energy efficient house are inevitably higher, they are balanced with lower operating costs and improved thermal comfort. The work is supported by a residential building project using Cross Laminated Timber (CLT) panels. This atypical project is compared with a typical New Zealand house (reference building), regarding both energy efficiency and costs. The current design of the CLT building is discussed according to passive design strategies, and a range of improvements for the building design is proposed. This final design proposal is determined by prioritizing investments in design options having the greatest effect on the building overall energy consumption. Building design features include windows efficiencies, insulation levels, optimized thermal mass, lighting fixture, as well as HVAC and domestic hot water systems options. The improved case for the CLT building is simulated having a total energy consumption of 4,860kWh/year, which corresponds to a remarkable 60% energy savings over the baseline. The construction cost per floor area is slightly higher for the CLT building, about 2,900$/m² against 2,500$/m² for the timber framed house. But a life cycle cost analysis shows that decreased operating costs makes the CLT house cost-competitive over its lifetime. The thesis suggests that the life cycle cost of the CLT house is 14% less than that of the reference building, while the improved CLT design reaches about 22% costs savings.
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Modeling the Impact of Assembly Tolerances Regarding Air Leaks on the Energy Efficiency and Durability of a Cross-Laminated Timber Structure

https://research.thinkwood.com/en/permalink/catalogue2365
Year of Publication
2019
Topic
Energy Performance
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Author
Martin, Ulysse
Blanchet, Pierre
Potvin, André
Publisher
BioResources
Year of Publication
2019
Country of Publication
United States
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Topic
Energy Performance
Design and Systems
Keywords
Energy Efficiency
Air Leakage
HAM Analysis
Durability Assessment
Language
English
Research Status
Complete
Series
BioResources
Summary
Air leaks have a considerable impact on the energy load and durability of buildings, particularly in cold climates. In wood construction using cross-laminated timber (CLT), air leaks are most likely to be concentrated at the joints between panels and other elements. This study used simulations of heat, air, and moisture transfers through a gap between two CLT panels causing air leakage in winter conditions under a cold climate. A real leakage occurrence was sized to validate the simulations. The aim of this work was to assess the impact on the energy loads and the durability of an air leak, as either infiltration or exfiltration, for different gap widths and relative humidity levels. The results showed that infiltrations had a greater impact on the energy load than exfiltrations but did not pose a threat to the durability, as opposed to exfiltrations. Gap sizes in CLT may vary, but the effect on the energy load was sensitive to the leakage path in the rest of the wall. As expected, a combination of winter exfiltration and a high level of interior relative humidity was particularly detrimental.
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Corss-Laminated Timber Buildings: A WBLCA Case Study Series

https://research.thinkwood.com/en/permalink/catalogue2360
Year of Publication
2019
Topic
Environmental Impact
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Walls
Author
Kwok, Alison
Zalusky, Hannah
Rasmussen, Linsday
Rivera, Isabel
McKay, Hannah
Organization
TallWood Design Institute
Year of Publication
2019
Country of Publication
United States
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Walls
Topic
Environmental Impact
Design and Systems
Keywords
LCA
Life-Cycle Assessment
Case Study
Embodied Carbon
Language
English
Research Status
Complete
Summary
This series highlights five whole building life cycle assessments (WBLCAs) of buildings incorporating the building material known as cross-laminated timber (CLT) into some or all of their structure, using a primary cradle-to-grave system boundary. This case study series will serve as an educational resource for academics, professionals, and CLT project stakeholders. While there is some uncertainty about the best way to reduce greenhouse gas emissions from architecture and construction, using CLT and other wood building materials is one possible means to reduce the emissions associated with a building’s materials. When forests are managed sustainably, wood construction materials can contribute to climate change mitigation goals as an indefinite carbon store and as a replacement of other fossil-fuel intensive materials. WBLCA is an assessment method to estimate the environmental impacts of buildings; this series offers insight into the current possibilities and limitations of WBLCA for CLT buildings. The series begins with background information on WBLCA methods and CLT, a review of previously published CLT building WBLCAs, and a life cycle assessment of an individual CLT wall element using the WBLCA softwares Tally® and Athena Impact Estimator for Buildings (Athena IE).
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Effect of Realistic Boundary Conditions on the Behaviour of Cross-Laminated Timber Elements Subjected to Simulated Blast Loads

https://research.thinkwood.com/en/permalink/catalogue2361
Year of Publication
2017
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Cote, Dominic
Publisher
University of Ottawa
Year of Publication
2017
Country of Publication
Canada
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Seismic
Keywords
Connections
Seismic Load
Blast Loads
Fasteners
Language
English
Research Status
Complete
Summary
Cross-laminated timber (CLT) is an emerging engineered wood product in North America. Past research effort to establish the behaviour of CLT under extreme loading conditions has focussed CLT slabs with idealized simply-supported boundary conditions. Connections between the wall and the floor systems above and below are critical to fully describing the overall behaviour of CLT structures when subjected to blast loads. The current study investigates the effects of “realistic” boundary conditions on the behaviour of cross-laminated timber walls when subjected to simulated out-of-plane blast loads. The methodology followed in the current research consists of experimental and analytical components. The experimental component was conducted in the Blast Research Laboratory at the University of Ottawa, where shock waves were applied to the specimens. Configurations with seismic detailing were considered, in order to evaluate whether existing structures that have adequate capacities to resist high seismic loads would also be capable of resisting a blast load with reasonable damage. In addition, typical connections used in construction to resist gravity and lateral loads, as well as connections designed specifically to resist a given blast load were investigated. The results indicate that the detailing of the connections appears to significantly affect the behaviour of the CLT slab. Typical detailing for platform construction where long screws connect the floor slab to the wall in end grain performed poorly and experienced brittle failure through splitting in the perpendicular to grain direction in the CLT. Bearing type connections generally behaved well and yielding in the fasteners and/or angles brackets meant that a significant portion of the energy was dissipated there reducing the energy imparted on the CLT slab significantly. Hence less displacement and thereby damage was observed in the slab. The study also concluded that using simplified tools such as single-degree-of-freedom (SDOF) models together with current available material models for CLT is not sufficient to adequately describe the behaviour and estimate the damage. More testing and development of models with higher fidelity are required in order to develop robust tools for the design of CLT element subjected to blast loading.
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An Algorithm for Numerical Modelling of Cross-Laminated Timber Structures

https://research.thinkwood.com/en/permalink/catalogue2362
Year of Publication
2015
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Author
D'Aronco, Gabriele
Publisher
Università di Padova
Year of Publication
2015
Country of Publication
Italy
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
General Application
Topic
Design and Systems
Keywords
Connections
Panels
Model
Language
English
Research Status
Complete
Summary
Cross-laminated timber, also known as X-Lam or CLT, is well established in Europe as a construction material. Recently, implementation of X-Lam products and systems has begun in countries such as Canada, United States, Australia and New Zealand. So far, no relevant design codes for X-Lam construction were published in Europe, therefore an extensive research on the field of cross-laminated timber is being performed by research groups in Europe and overseas. Experimental test results are required for development of design methods and for verification of design models accuracy. This thesis is part of a large research project on the development of a software for the modelling of CLT structures, including analysis, calculation, design and verification of connections and panels. It was born as collaboration between Padua University and Barcelona"s CIMNE (International Centre for Numerical Methods in Engineering). The research project started with the thesis “Una procedura numerica per il progetto di edifici in Xlam” by Massimiliano Zecchetto, which develops a software, using MATLAB interface, only for 2D linear elastic analysis. Follows the phase started in March 2015, consisting in extending the 2D software to a 3D one, with the severity caused by modelling in three dimensions. This phase is developed as a common project and described in this thesis and in “Pre-process for numerical analysis of Cross Laminated Timber Structures” by Alessandra Ferrandino. The final aim of the software is to enable the modelling of an X-Lam structure in the most efficient and reliable way, taking into account its peculiarities. Modelling of CLT buildings lies into properly model the connections between panels. Through the connections modelling, the final aim is to enable the check of preliminarily designed connections or to find them iteratively, starting from hypothetical or random connections. This common project develops the pre-process and analysis phases of the 3D software that allows the automatic modelling of connections between X-Lam panels. To achieve the goal, a new problem type for GiD interface and a new application for KRATOS framework have been performed. The problem type enables the user to model a CLT structure, starting from the creation of the geometry and the assignation of numeric entities (beam, shell, etc.) to geometric ones, having defined the material, and assigning loads and boundary conditions. The user does not need to create manually the connections, as conversely needs for all commercial FEM software currently available; he just set the connection properties to the different sides of the panels. The creation of the connections is made automatically, keeping into account different typologies of connections and assembling of Cross-Lam panels. The problem type is special for XLam structures, meaning that all features are intentionally studied for this kind of structures and the software architecture is planned for future developments of the postprocess phase. It can be concluded that sound bases for the pre-process and analysis phases of the software have been laid. However, future research is required to develop the postprocess and verification phases of the research project.
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Free
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Encapsulated Mass Timber Construction - Cost Comparison Canada: Construction, Time & Maintenance Cost-Benefit Report

https://research.thinkwood.com/en/permalink/catalogue2359
Year of Publication
2017
Topic
Cost
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Columns
Floors
Organization
Hanscomb
Publisher
National Research Council Canada
Year of Publication
2017
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Columns
Floors
Topic
Cost
Keywords
Encapsulated Mass Timber Construction
Building Code
Time
Construction Time
Construction Cost
Maintenance Cost
Cost-Benefit Analysis
Language
English
Research Status
Complete
Summary
The Task Group on Combustible Construction is in the process of evaluating a proposed code change request related to buildings of encapsulated mass timber construction (EMTC). As part of the analysis of the code change request, an impact analysis is required that includes a cost-benefit analysis. Hanscomb was hired to provide a cost-benefit analysis and to compare the estimated value of the following: 1. The cost of constructing a building of mass timber (unprotected) versus a building constructed of encapsulated mass timber (e.g. mass timber protected with a double layer of Type X gypsum board) versus a traditional concrete and steel building. 2. The time to build a building of mass timber construction (unprotected) versus a building of encapsulated mass timber construction versus a traditional concrete and steel building. 3. The annual maintenance costs of building of mass timber construction versus a building of encapsulated mass timber construction versus a traditional concrete and steel building. For the purposes of this study two sets of conceptual floor plans and elevations have been created: 1. A 12 storey building with a Group C major occupancy (residential) where each storey is 6,000 m2 in floor area. 2. A 12 storey building with a Group D major occupancy (office) where each storey is 7,200 m2 in floor area.
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