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8 records – page 1 of 1.

Elevated Temperature Effects on the Shear Performance of a Cross-Laminated Timber (CLT) Wall-to-Floor Bracket Connection

https://research.thinkwood.com/en/permalink/catalogue2106
Year of Publication
2019
Topic
Fire
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Author
Mahr, Kolton
Organization
Oregon State University
Year of Publication
2019
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Topic
Fire
Connections
Mechanical Properties
Keywords
Fire Performance
Cyclic Shear Tests
Wall-to-Floor
Brackets
Thermal Degradation
Strength
Elastic Stiffness
Model
Temperature
Research Status
Complete
Summary
Connections in mass timber structural systems dissipate energy and transfer lateral forces from mass timber elements such as shear walls and diaphragms, providing critical load paths. Cross-laminated timber (CLT) is a prominent mass timber material used to manufacture wall and floor assemblies. Fire performance research of CLT walls and floors has been abundant in recent years in an effort to address concerns about fires in tall wood buildings. Some fire-protected structural elements, including connections, may not be directly exposed to flames in a fire event but will experience elevated temperatures. There is limited research on elevated temperature performance of CLT connections, and consequentially a lack of full understanding of the fire performance of CLT structures. Therefore, a series of cyclic shear tests were conducted on a CLT wall-to-floor bracket connection assembly to characterize thermal degradation according to a matrix of 28 exposure duration-temperature combinations. The first study developed simple models to predict thermal degradation of two basic engineering parameters, peak strength and elastic stiffness. The second study used two different methods to develop force-displacement backbone models from the experimental hysteresis data. Results from both studies indicate significant thermal degradation of the connection performance at elevated temperatures ranging between 75 °C to 200 °C. This research is a step towards holistic evaluation of elevated temperature modeling of CLT structures.
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Hybrid LVL Panels Made of Eucalypt and Pine Woods Decayed by White-Rot Fungus

https://research.thinkwood.com/en/permalink/catalogue2228
Year of Publication
2018
Topic
Moisture
Material
LVL (Laminated Veneer Lumber)

Mechanical Performance of Laminated Veneer Lumber and Glulam Beams After Short-Term Incident Heat Exposure

https://research.thinkwood.com/en/permalink/catalogue2733
Year of Publication
2020
Topic
Mechanical Properties
Fire
Design and Systems
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Beams
Author
Gales, John
Chorlton, Bronwyn
Year of Publication
2020
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Beams
Topic
Mechanical Properties
Fire
Design and Systems
Keywords
Radiant Heat
Adhesive Strength Loss
Fire Design
Performance
Degradation
Research Status
Complete
Series
Construction and Building Materials
Summary
Timber use is becoming more appealing in the recent years especially ‘exposed timber’; however, the information available on the performance of engineered timber after fire is limited. This paper explores the performance of timber elements exposed to well defined thermal boundary conditions and examines the extent of adhesive degradation after heating. Two different types of timber beams are explored; ‘glued laminated timber’ (Glulam) and ‘laminated veneer lumber’ (LVL). A subset of beams was exposed to radiant heat as per a modified ASTM E1321 heating procedure. An additional subset of beams also had an area of their cross-section carved away, equivalent to the char depth of the heated beams. The carved beams allow for the identification of degradation beyond the char layer, as theoretically both the carved and charred beams would have the same effective cross-sectional area. All beams were mechanically loaded to failure using a four-point loading setup. While the current allowance for degradation beyond the char layer is considered to be 7 mm for exposure times of 20 minutes and greater [1], the results herein indicate that for bending members this layer extends to at least a minimum of 11.7 mm for LVL and 12.3 mm for Glulam. The aim of this paper is to assess the post-fire performance of Glulam and LVL through looking at strength loss due to adhesive degradation, which may contribute towards enabling tall and unencapsulated engineered timber buildings.
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A Method to Characterize Biological Degradation of Mass Timber Connections

https://research.thinkwood.com/en/permalink/catalogue2724
Year of Publication
2020
Topic
Connections
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Sinha, Arijit
Udele, Kenneth
Cappellazzi, Jed
Morrell, Jeff
Year of Publication
2020
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Serviceability
Keywords
Biological Durability
Fungal Degradation
Fungus
Connection Strength
Research Status
Complete
Series
Wood and Fiber Science
Summary
Biological durability issues in cross-laminated timber (CLT) have been majorly ignored in North America because of the European origin of the material and careful construction practices in Europe. However, the risks of fungal and insect attacks are increased by the North American climatic conditions and lack of job-site measures to keep the material dry. The methods to evaluate durability in solid timber are inadequate for use in mass timber (MT) for a number of reasons, such as moisture variation and size being critical issues. This study therefore proposes a method, which is suitable to evaluate the strength of MT assemblies that are exposed to fungal degradation. The objective of the study was to explore a controlled method for assessing the effects of wetting and subsequent fungal attack on the behavior of CLT connections. Two different methods were used to create fungal attack on CLT assemblies. Although they were both successful, one was cumbersome, left room for many errors, and was not as efficient as the other. In addition, a standardized method to evaluate and characterize key performance metric for the connections is presented.
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Free
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Mid-Rise Wood Constructions: Specifications of Mid-Rise Envelopes for Hygrothermal Assessment

https://research.thinkwood.com/en/permalink/catalogue754
Year of Publication
2014
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Solid-sawn Heavy Timber
Application
Wood Building Systems
Author
Abdulghani, Khaled
Cornick, Steve
Di Lenardo, Bruno
Ganapathy, Gnanamurugan
Lacasse, Michael
Maref, Wahid
Moore, Travis
Mukhopadhyaya, Phalguni
Nicholls, Mike
Saber, Hamed
Swinton, Michael
Organization
National Research Council of Canada
Year of Publication
2014
Format
Report
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Solid-sawn Heavy Timber
Application
Wood Building Systems
Topic
Serviceability
Keywords
Hygrothermal
Mid-Rise
Building Envelope
Long-term
Degradation
Research Status
Complete
Summary
The role of the Building Envelope team in this project is to assess whether alternate wood-based building envelope solutions developed by the Fire Team to meet the fire provisions of NBC 2010, also meet NBC Part 5 requirements relating to the protection of the building envelope from long term degradation due to uncontrolled heat, air, moisture and precipitation (HAMP) ingress into the building envelope of mid-rise buildings. In a process of consultations with stakeholders, including the Canadian Wood Council (CWC), FPInnovations, and consultations with NRC’s Fire and Acoustics teams, specifications were developed for 2.44 m x 2.44 m wall specimens that would be investigated for hygrothermal performance.
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Free
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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
Author
Liu, Jingjing
Lam, Frank
Foschi, Ricardo
Li, Minghao
Year of Publication
2019
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Connections
Keywords
Coupling Effect
Biaxial loading
Degradation
Modeling
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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Numerical Simulation for the Seismic Behaviour of Mid-Rise CLT Shear Walls with Coupling Beams

https://research.thinkwood.com/en/permalink/catalogue200
Year of Publication
2014
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Wood Building Systems
Author
Liu, Jingjing
Lam, Frank
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Wood Building Systems
Topic
Seismic
Keywords
Deflection
Degradation
Energy Dissipation
Force
Resistance
Stiffness
Strength
Numerical model
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
In this paper, an innovative type of mid-rise Cross Laminated Timber shear walls with coupling beams was designed. The 5-layer CLT panels were continuous along the height. Hold-downs and angle brackets were installed at the bottom of the panels. Coupling beams with energy dissipation devices were used to decrease the deformation and internal forces of the walls, providing adequate stiffness and strength. A numerical model was developed in OpenSees for a six storey prototype to investigate its seismic behaviour with different configurations. Strength degradation, stiffness degradation, and pinching effect were considered in the connection models. The structural performance was evaluated through a series of static and transient analyses. The simulation results indicated adequate lateral resistance and deformation capacity of this structural type. This study will lead to more application of large size CLT panels in multi-storey CLT buildings as lateral resistant systems.
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Free
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Physical, Optical, and Visual Performance of Coated Cross-Laminated Timber during Natural and Artificial Weathering

https://research.thinkwood.com/en/permalink/catalogue2983
Year of Publication
2021
Topic
General Information
Material
CLT (Cross-Laminated Timber)
Author
Bobadilha, Gabrielly
Stokes, C. Elizabeth
Ohno, Katie
Kirker, Grant
Lopes, Dercilio
Nejad, Mojgan
Organization
Mississippi State University
Forest Products Laboratory
Michigan State University
Editor
Sandak, Anna
Publisher
MDPI
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
General Information
Keywords
Surface Protection
Outdoor Exposure
Artificial Weathering
Wood Degradation
Research Status
Complete
Series
Coatings
Summary
Cross-laminated timber (CLT) market demand is on the rise in the United States. Adequate protective measures have not been extensively studied. The objective of this study was to investigate the weathering performance of exterior wood coatings. We evaluated coated CLT sample surfaces based on visual appearance, color change (CIE*L*a*b), gloss changes, and water intrusion. From the five exterior wood coatings evaluated, only two showed adequate performance after twelve months field exposure. Based on visual ratings following the ASTM procedures, coating failure occurs more quickly in Mississippi than in Wisconsin, due to its greater decay zone. Both location and coating type impacted the aging of the samples. Artificial weathering results were consistent with natural weathering indicating the two adequate coatings were the most resistant to failure, color, and gloss change. For future studies, new coatings designed for the protection of end-grain in CLT panels should be a target of research and development.
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Free
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8 records – page 1 of 1.