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18 records – page 1 of 2.

Differential Material Movement in Tall Mass Timber Structures

https://research.thinkwood.com/en/permalink/catalogue2982
Year of Publication
2022
Topic
Moisture
Application
Wood Building Systems
Author
Racine, Josephine
Lumpkin, Bryce
McLain, Richard
Organization
Fast + Epp
WoodWorks
Year of Publication
2022
Format
Report
Application
Wood Building Systems
Topic
Moisture
Keywords
Column Movement
Vertical Movement
Creep
Settlement
Shrinkage
Crushing Perpendicular to Grain
Research Status
Complete
Summary
As the height of mass timber buildings continues to grow, a new set of design and detailing challenges arises, creating the need for new engineering solutions to achieve optimal building construction and performance. One necessary detailing consideration is vertical movement, which includes column shrinkage, joint settlement, and creep. The main concerns are the impact of deformations on vertical mechanical systems, exterior enclosures, and interior partitions, as well as differential vertical movement of timber framing systems relative to other building features such as concrete core walls and exterior façades.
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Mass Timber Connections Index: Optimal Connection Considerations

https://research.thinkwood.com/en/permalink/catalogue2997
Year of Publication
2021
Topic
Connections
Author
Kinder, Erin
Kingsley, Greg
Organization
KL&A Engineers & Builders
Publisher
WoodWorks
Year of Publication
2021
Format
Report
Topic
Connections
Keywords
Aesthetics
Construction Tolerances
Constructability
Moisture
Shrinkage
Fire Rating
Cost
Research Status
Complete
Summary
The cost of connections in a mass timber structure can significantly affect the overall project cost; however, because mass timber connection design must consider not only structural design but also aesthetics, fire-rating requirements, constructability, accommodations for shrinkage and swelling, and moisture protection, finding the optimal solution can be challenging. To assist designers in this effort, WoodWorks has published an easy to use index highlighting the spectrum of available structural and architectural mass timber connections. The intent is to facilitate the selection of cost-optimal connection types while balancing other important considerations. This paper focuses on the structural connections in the index, addressing each of these considerations.
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Determination of the Moisture Change Behavior of Cross-Laminated Timber Using an Optical Flow Based Computer Vision Technique

https://research.thinkwood.com/en/permalink/catalogue2229
Year of Publication
2019
Topic
Moisture
Material
CLT (Cross-Laminated Timber)
Author
Hofinger, Markus
Pock, Thomas
Moosbrugger, Thomas
Organization
Graz University of Technology
Publisher
Taylor&Francis Online
Year of Publication
2019
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Moisture
Keywords
Deformation
Swelling
Shrinkage
Research Status
Complete
Series
Wood Material Science & Engineering
Summary
Although cross-laminated timber (CLT) offers greatly improved directional stability against moisture changes compared to lumber, some layup dependent directional differences still remain. Furthermore, even under a purely homogeneous distributed moisture change strong deformations appear along the boundaries, which show a decrease of swelling/shrinkage towards the inside of CLT panels. Metrological determination of this behavior is still a challenging task and involves long-lasting moisture content conditioning and typically manual measurements. This limits the amount of measurable data-points and thus the gain-able insights. We apply a recently introduced computer vision technique based on optical flow from scan images to measure surface deformation fields of various CLT specimens with different layups. This allows us to measure the change of average differential swelling and shrinkage coefficients throughout the cross section and visualize them as curves with high resolution. We gain measurements for each image pixel and demonstrate good matching to previously published manual single-point measurements. Furthermore, we analyze various specimens specifically built to allow for investigations of the aforementioned boundary effects. Using the computer vision approach we are able to show how the combination of homogeneous deformations and boundary effects leads to the resulting deformations observable with manual methods.
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Effects of Size, Species and Adjacent Lamina on Moisture Related Strain in Glulam

https://research.thinkwood.com/en/permalink/catalogue2443
Year of Publication
2019
Topic
Design and Systems
Moisture
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Lee, So Sun
Pan, Sung Jun
Jeong, Gi Young
Organization
Chonnam National University
Year of Publication
2019
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Moisture
Keywords
Coefficient of Moisture Expansion
Coefficient of Moisture Shrinkage
Digital Image Correlation
Strain
Research Status
Complete
Series
Wood and Fiber Science
Summary
The goal of this study was to investigate the effects of size and species on moisture-related strain in glued–laminated timber (glulam). Swelling and shrinkage behaviors of different sizes (120 120, 180 180, and 180 240 mm2) of glulam made from larch and pine were measured using digital image correlation. A new approach to predict dimensional changes of glulam was developed by reflecting the nonlinear behavior of shrinkage based on MC change. It was compared with the existing method provided by the American Wood Council (AWC). Moisture-related strains of glulam were significantly influenced by size and species. Coefficients of swelling or shrinkage of glulam were determined to indicate statistical significance. When MC was changed from saturated condition to EMC of 12%, differences in dimensional changes in the width direction between experimental test and prediction results using the AWC method ranged from 87.7% to 260.0%. However, differences in dimensional changes in the width direction between experimental test and prediction results using the newly developed method ranged from 1.8% to 15.9%. Strains in the width direction of glulam could be affected by adjacent laminas along the glue line and the new approach could account for the effects. However, the AWC method could not reflect the effects of adjacent laminas along the glue line. Therefore, better prediction accuracy was achieved by using the new approach.
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Dimensional Changes of Cross-Laminated Specimens Produced under Different Conditions due to Humidity Variation

https://research.thinkwood.com/en/permalink/catalogue2474
Year of Publication
2019
Topic
Moisture
Material
CLT (Cross-Laminated Timber)
Author
Han, Yeonjung
Park, Yonggun
Yang, Sang-Yun
Chung, Hyunwoo
Chang, Yoon-Seong
Yeo, Hwanmyeong
Organization
Seoul National University
Publisher
North Carolina State University
Year of Publication
2019
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Moisture
Keywords
Humidity
Moisture Content
Larch
Shrinkage
Research Status
Complete
Series
BioResources
Summary
Cross-laminated timber (CLT) is becoming increasingly adopted into wooden construction of South Korea. Due to the lack of standards and protocol for CLT, there are many problems in the production and utilization phases. This study focused on the deformation and defects of CLT due to humidity variations. In this study, small, cross-laminated specimens were manufactured using three layers of laminated larch planks that had various moisture contents. The dimensional changes of these specimens were measured in response to changing internal conditions including side adhesion or moisture content variation and external conditions such as humidity. Shrinkage in width and thickness was less than 1.0% when using dry planks as the cross-laminated specimen. However, high-moisture content (MC) planks were not suitable when used as the surface layer of the CLT, as the shrinkage in width and thickness were greater than 2.0%. When high-MC planks are used in the inner layer, their shrinkage must be less than 2% to prevent splitting caused by a MC difference between the surface and inner planks. For this purpose, laminates with a MC less than 15% should be used for CLT.
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Long-term Tensile Behaviour of Engineered Wood in Parallel to Grain Direction

https://research.thinkwood.com/en/permalink/catalogue2082
Year of Publication
2018
Topic
Serviceability
Material
LVL (Laminated Veneer Lumber)
Author
Chiniforush, Alireza
Akbarnezhad, Ali
Thakore, Prajeet
Ataei, Abdolreza
Organization
University of New South Wales
Year of Publication
2018
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Topic
Serviceability
Keywords
Visco-Elastic
Mechanosorption Creep
Shrinkage
Swelling
Deformation
Tensile Load
Long-term
Temperature
Relative Humidity
Numerical Model
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
Long-term serviceability is an important aspect in the implication of wood as a construction material. In this study, a comprehensive experimental program aims to address all the required parameters in long-term constitutive models of wood available in the literature which was taken from inconsistent sources earlier. The experimental program considers the effect of viscoelastic and mechano-sorptive creep, shrinkage and swelling, thermal and moisture inelastic deformation, and deformation due to Young’s modulus changes. The tests include tensile loading of wood specimens invariable outdoor climatic conditions in different applied stress levels. Sustained tensile loads were applied in parallel to the grain direction to specimens of Splash Pine (Pinus elliottii), Pacific Teak (Tectona grandis), and Laminated Lumber Veneer (LVL) of Radiata Pine (Pinus radiata). Tests were conducted at three different stress levels simultaneously and environmental parameters viz. temperature and relative humidity were monitored continuously throughout the loading period. Complementary data for diffusion coefficient, shrinkage, and swelling were measured in three orthogonal directions. In addition, sorption-desorption isotherm of the sample in the range of 0-100% relative humidity is presented.
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Accommodating Shrinkage in Multi-Story Wood-Frame Structures

https://research.thinkwood.com/en/permalink/catalogue712
Year of Publication
2017
Topic
Design and Systems
Moisture
Material
Light Frame (Lumber+Panels)
Application
Wood Building Systems
Author
McLain, Richard
Steimle, Doug
Organization
WoodWorks
Year of Publication
2017
Format
Report
Material
Light Frame (Lumber+Panels)
Application
Wood Building Systems
Topic
Design and Systems
Moisture
Keywords
Shrinkage
Mid-Rise
Multi-Story
Moisture Content
Research Status
Complete
Summary
In wood-frame buildings of three or more stories, cumulative shrinkage can be significant and have an impact on the function and performance of finishes, openings, mechanical/electrical/plumbing (MEP) systems, and structural connections. However, as more designers look to wood-frame construction to improve the cost and sustainability of their mid-rise projects, many have learned that accommodating wood shrinkage is actually very straightforward. This publication will describe procedures for estimating wood shrinkage and provide detailing options that minimize its effects on building performance.
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Free
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Structural Design, Approval, and Monitoring of a UBC Tall Wood Building

https://research.thinkwood.com/en/permalink/catalogue1252
Year of Publication
2017
Topic
Serviceability
Mechanical Properties
Design and Systems
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Hybrid Building Systems
Author
Tannert, Thomas
Moudgil, Ermanu
Organization
Structures Congress
Publisher
American Society of Civil Engineers
Year of Publication
2017
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Hybrid Building Systems
Topic
Serviceability
Mechanical Properties
Design and Systems
Keywords
Vertical Shrinkage
Horizontal Building Vibration
Structural Performance
Concrete Core
Brock Commons
Conference
Structures Congress 2017
Research Status
Complete
Notes
April 6–8, 2017, Denver, Colorado
Summary
In this paper, we discuss the structural design of one of the tallest timber-based hybrid buildings in the world: the 18 storey, 53 meter tall student residence on the campus of the University of British Columbia in Vancouver. The building is of hybrid construction: 17 storeys of mass wood construction on top of one storey of concrete construction. Two concrete cores containing vertical circulation provide the required lateral resistance. The timber system is comprised of cross-laminated timber panels, which are point supported on glued-laminated timber columns and steel connections between levels. In addition to providing more than 400 beds for students, the building will serve as an academic site to monitor and study its structural performance, specifically horizontal building vibration and vertical shrinkage considerations. We present the challenges relating to the approval process of the building and discuss building code compliance issues.
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Field Measurement of Vertical Movement and Roof Moisture Performance of the Wood Innovation and Design Centre: Instrumentation and First Year's Performance

https://research.thinkwood.com/en/permalink/catalogue102
Year of Publication
2015
Topic
Design and Systems
Serviceability
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Wang, Jieying
Organization
FPInnovations
Year of Publication
2015
Format
Report
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Serviceability
Keywords
Differential Movement
Long-term
Moisture
Plywood
Roofs
Shrinkage
Tall Wood
Vertical Movement
Research Status
Complete
Summary
Two of the major topics of interest to those designing taller and larger wood buildings are the susceptibility to differential movement and the likelihood of mass timber components drying slowly after they are wetted during construction. The Wood Innovation and Design Centre in Prince George, British Columbia provides a unique opportunity for non-destructive testing and monitoring to measure the ‘As Built’ performance of a relatively tall mass timber building. Field measurements also provide performance data to support regulatory and market acceptance of wood-based systems in tall and large buildings. This report first describes instrumentation to measure the vertical movement of selected glulam columns and cross-laminated timber (CLT) walls in this building. Three locations of glulam columns and one CLT wall of the core structure were selected for measuring vertical movement along with the environmental conditions (temperature and humidity) in the immediate vicinity. The report then describes instrumentation to measure the moisture changes in the wood roof structure. Six locations in the roof were selected and instrumented for measuring moisture changes in the wood as well as the local environmental conditions.
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Monitoring Building Climate and Timber Moisture Gradient in Large-Span Timber Structures

https://research.thinkwood.com/en/permalink/catalogue108
Year of Publication
2014
Topic
Serviceability
Moisture
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Gamper, Andreas
Dietsch, Philipp
Winter, Stefan
Editor
Bettina Franke Steffen Franke
Year of Publication
2014
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Serviceability
Moisture
Keywords
Cracks
Damage
Equilibrium Moisture Content
Internal Climate
Lamellas
Large Span
Long-term
Relative Humidity
Shrinkage
Swelling
Temperature
Conference
COST Workshop – Highly Performing Timber Structures: Reliability, Assessment, Monitoring and Strengthening
Research Status
Complete
Summary
The evaluation of damages in large-span timber structures indicates that the predominantly observed damage pattern is pronounced cracking in the lamellas of glued-laminated timber elements. A significant proportion of these cracks is attributed to the seasonal and use-related variations of the internal climate within large buildings and the associated inhomogeneous shrinkage and swelling processes in the timber elements. To evaluate the significance of these phenomena, long-term measurements of climatic conditions and timber moisture content were taken within large-span timber structures in buildings of typical construction type and use. These measurements were then used to draw conclusions on the magnitude and time necessary for adjustment of the moisture distribution to changing climatic conditions. A comparison of the results for different types of building use confirms the expected large range of possible climatic conditions in buildings with timber structures. Ranges of equilibrium moisture content representative of the type and use of building were obtained. These ranges can be used in design to condition the timber to the right value of moisture content, in this way reducing the crack formation due to moisture variations. The results of this research also support the development of suitable monitoring systems which could be applied in form of early warning systems on the basis of climate measurements. Based on the results obtained, proposals for the practical implementation of the results are given.
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Free
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18 records – page 1 of 2.