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8 records – page 1 of 1.

Advanced Quality and In-Service Condition Assessment Procedures for Mass Timber and Cross-Laminated Timber Products

https://research.thinkwood.com/en/permalink/catalogue2558
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Organization
Forest Products Laboratory
Mississippi State University
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Non-Destructive Evaluation
Bond Performance
Monitoring Techniques
Serviceability
Quality Assurance
Research Status
In Progress
Notes
Project contacts are Frederico França at Mississippi State University and Robert J. Ross at the Forest Products Laboratory
Summary
With the rapid development of CLT manufacturing capacity around the world and the increasing architectural acceptance and adoption, there is a current and pressing need regarding adhesive bond quality assurance in manufacturing. As with other engineered glued composites, adhesive bondline performance is critically important. Bondline assessment requires technology in the form of sensors, ultrasonics, load cells, or other means of reliable machine evaluation. The objectives of this cooperative study are to develop quality assurance procedures for monitoring the quality of mass timber and CLT during and after manufacturing and to develop assessment techniques for CLT panels in-service.
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Analytical and experimental evaluation of the effect of knots on rolling shear properties of cross-laminated timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue1942
Year of Publication
2019
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Cao, Yawei
Organization
Mississippi State University
Year of Publication
2019
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Rolling Shear
Southern Pine
Center Point Bending Test
Two-Plate Shear Test
Knots
Strength
Failure Mechanism
Research Status
Complete
Summary
Knots are usually regarded as defects when grading lumber. In order to evaluate a member under out-of-plane loading, shear strength is one of the major mechanical properties, specifically, rolling shear (RS) strength is one of the critical mechanical properties of Cross-Laminated Timber (CLT), which determines the flexural strength of CLT under short-span bending loads. Lower grade lumber with a higher percentage of knots is recommended to be utilized for the cross-layer laminations which are mainly responsible for resisting shear stresses. Firstly, shear tests were performed in order to evaluate the effect of knots on longitudinal shear strength using shear blocks. After that, the effect of knots on the RS strength of 3-ply southern yellow pine CLT were investigated by experimental tests and an analytical model. Center-point bending tests with a span-to-depth ratio of 6 and two-plate shear tests with a loading angle of 14° were conducted on six CLT configurations composed of different types of cross layer laminations: clear flatsawn lumber with/without pith, lumber with sound knots with/without pith, and lumber with decayed knots with/without pith. The shear analogy method was implemented to evaluate the RS strength values from the bending test results, which were also compared against the results from the two-plate shear tests. It was found that: (1) The shear blocks containing sound knots had higher shear strength than matched clear shear blocks, the shear blocks containing unsound knots had lower shear strength than the matched clear shear blocks. (2) CLT specimens with cross-layer laminations with either sound knots or decayed knots had higher RS strength. (3) In general, the shear analogy method underestimated the RS strength of CLT specimens containing knots and pith.
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Cross-Laminated Timber (CLT) Resistance to Infestation by Subterranean Termites

https://research.thinkwood.com/en/permalink/catalogue2265
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Organization
Mississippi State University, USDA Forest Service Forest Products Laboratory
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Biodegradation
Research Status
In Progress
Notes
Contact: C. Elizabeth Stokes, Mississippi State University, Juliet Tang, Forest Products Laboratory
Summary
Outcomes anticipated from the results of this project are biodegradation information for CLT products and an improved understanding of biodegradation differences between CLT products and comparable laminated and solid wood products. Results will benefit the emerging CLT industry and provide valuable information for market expansion into areas with high termite pressure.
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Development of Preservative-treated Southern Pine Cross-laminated Timber

https://research.thinkwood.com/en/permalink/catalogue2566
Topic
Moisture
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Industrial Application
Organization
Mississippi State University
Material
CLT (Cross-Laminated Timber)
Application
Industrial Application
Topic
Moisture
Mechanical Properties
Keywords
Industrial Mats
Preservative Treatment
Weathering
Durability
Research Status
In Progress
Notes
Project contact is Hyungsuk Lim at Mississippi State University
Summary
This project aims to develop the preservative-treatment procedures for industrial cross-laminated timber (CLT) mats composed of southern yellow pine (SYP) lumber. The feasibility of pre- and post-treating CLT panels with an environment-friendly preservative system for ground-contact applications at an industrial scale will be evaluated from adhesion, mechanical, and durability performance aspects. As for the pre-treatment method, CLT panels will be consolidated with preservative-treated lumber adopting industrial CLT manufacturing parameters, including glue-type and clamping pressure. Alternatively, conventional CLT panels will be pressure treated with the same preservative system and dried afterward. As one of the primary focuses of the research, drying schedules which would not damage wood or adhesive layers will be determined. Also, penetration and retention of the preservatives throughout the post-treated panels will be analyzed. Adhesion and mechanical performance of the treated panels will be evaluated according to industry-accepted standards. Durability performance of the treated panels will be examined through laboratory weathering and on-site field tests.
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Effect of Notches on the Performance of Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue2559
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Organization
Forest Products Laboratory
Mississippi State University
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Notches
Notched Connections
Bending Properties
Flexural Properties
Research Status
In Progress
Notes
Project contacts are Robert J. Ross at the Forest Products Laboratory and Rubin Shmulsky at Mississippi State University
Summary
Notches, particularly when incorporated on the tensile face, influence the ultimate capacity of members, such as beams and floor panels. Understanding and quantification of failure modes, ductility, and strength of notched CLT floor panels can allow the safe application of notches on building construction. Despite wood’s ductility, notches are known areas of stress concentration. The 2018 International Residential Code for one- and two-family dwellings (International Code Council 2017) restricts the use of notches on engineered wood products by requiring structural calculations instead of elucidating the ways notches might be used. To employ CLT to its maximum potential, there is a current and pressing need for better knowledge regarding the influence of notches on flexural performance. This research seeks to review the literature regarding notches in solid and engineered beams, review typical CLT design details that employ or utilized notched panels, and conduct pilot-scale testing of notched CLT panels.
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Evaluating Decay Resistance of Mass Timber

https://research.thinkwood.com/en/permalink/catalogue718
Topic
Serviceability
Material
CLT (Cross-Laminated Timber)
Organization
Forest Products Laboratory Mississippi State University
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Keywords
Funghi
Decay
Research Status
In Progress
Notes
Project contacts are Grant Kirker (Forest Products Laboratory), Katie Ohno (Forest Products Laboratory) and C. Elizabeth Stokes (Mississippi State University)
Summary
Mass timber, as a renewable prefabricated structural panel material, is seen as highly desirable in the “green” building movement and has excellent thermal insulation, sound insulation, and fire restriction qualities. CLT is one of the more recent additions to the mass timber market worldwide, and although the product has undergone structural property testing in several laboratories, degradation testing of this non-preservative-treated product has only recently been initiated (Singh and Page 2016). Preliminary testing with exposure to Oligoporus placenta and Antrodia xantha indicated that untreated CLT is susceptible to the spread of mold and decay fungi, while treatment with boron somewhat reduced the extent of the decay fungus spread (Singh and Page 2016). These panels are easily handled on-site and have a much higher strength-to-weight ratio than their precast concrete competitors, which make them ideal for rapid construction of modular buildings, including apartment/condominium structures (Van de Kuilen et al. 2011). However, installations using CLT as a primary structural component in humid/damp climates, such as the southeastern United States, may be heavily affected by molds and decay fungi, and effects on CLT strength should be determined prior to widespread use of the product in these areas.
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Non-Destructive Lumber and Engineered Pine Products Research in the Gulf South U.S. 2005–2020

https://research.thinkwood.com/en/permalink/catalogue3070
Year of Publication
2021
Topic
General Information
Author
Seale, R. Dan
Shmulsky, Rubin
Franca, Frederico Jose Nistal
Organization
Mississippi State University
Publisher
MDPI
Year of Publication
2021
Format
Journal Article
Topic
General Information
Keywords
Nondestructive Evaluation
Pine Lumber
Modulus of Rupture
Modulus of Elasticity
Mass Timber
Acoustic Velocity
Transverse Vibration
Structural Lumber
Engineered Wood Products
Research Status
Complete
Series
Forests
Summary
This review primarily describes nondestructive evaluation (NDE) work at Mississippi State University during the 2005–2020 time interval. Overall, NDE is becoming increasingly important as a mean of maximizing and optimizing the value (economic, engineering, utilitarian, etc.) of every tree that comes from the forest. For the most part, it focuses on southern pine structural lumber, but other species such as red pine, spruce, Douglas fir, red oak, and white oak and other products such as engineered composites, mass timber, non-structural lumber, and others are included where appropriate. Much of the work has been completed in conjunction with the U.S. Department of Agriculture, Forest Service, Forest Products Laboratory as well as the Agricultural Research Service with the overall intent of improving lumber and wood products standards and valuation. To increase the future impacts and adoption of this NDE-related work, wherever possible graduate students have contributed to the research. As such, a stream of trained professionals is a secondary output of these works though it is not specifically detailed herein.
Online Access
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.