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6 records – page 1 of 1.

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
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
Online Access
Free
Resource Link
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Laminated Strand Lumber (LSL) Reinforced by GFRP; Mechanical and Physical Properties

https://research.thinkwood.com/en/permalink/catalogue1311
Year of Publication
2018
Topic
Mechanical Properties
Design and Systems
Material
LSL (Laminated Strand Lumber)
Author
Moradpour, Payam
Pirayesh, Hamidreza
Gerami, Masood
Jouybari, Iman
Publisher
ScienceDirect
Year of Publication
2018
Format
Journal Article
Material
LSL (Laminated Strand Lumber)
Topic
Mechanical Properties
Design and Systems
Keywords
GFRP
Poplar
Modulus of Rupture
Modulus of Elasticity
Shear Strength
Compression Strength
Impact Strength
Water Absorption
Thickness Swelling
Research Status
Complete
Series
Construction and Building Materials
Summary
The effect of glass fiber reinforced polymer (GFRP) on the technical properties of LSL made from poplar (Populus deltoids L.) employing pMDI and UF as binders was investigated. Technical properties such as modulus of rupture (MOR), Modulus of elasticity (MOE), shear strength (SS), compression strength parallel to the grains (CS //), impact strength (IS), water absorption (WA) and thickness swelling (TS) were determined. Results confirmed that resin type and GFRP have significant effects on the LSL properties. It was revealed that the most beneficial effect of GFRP is on MOR, MOE, IS, SS and CS respectively. The Highest properties were obtained by using pMDI as the resin and GFRP as the reinforcement, where properties such as MOR, MOE, IS, SS and CS were improved by 123, 114, 100, 94, and 90%, respectively, compared to control samples. Furthermore, GFRP incorporation led to alteration of fracture place from tension side to compression side. Depending on the treatment type, the WA and TS values of the LVLs improved between 23% to 68% and 19.5% to 78%, respectively.
Online Access
Free
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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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Free
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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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Self-camber of timber beams by swelling hardwood inlays for timber–concrete composite elements

https://research.thinkwood.com/en/permalink/catalogue2950
Year of Publication
2021
Topic
Mechanical Properties
Moisture
Material
Timber-Concrete Composite
Application
Beams
Author
Müller, Katharina
Grönquist, Philippe
Cao, Alex
Frangi, Andrea
Organization
ETH Zurich
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
Timber-Concrete Composite
Application
Beams
Topic
Mechanical Properties
Moisture
Keywords
Self-Camber
Swelling
Serviceability Limit State
European Beech
Research Status
Complete
Series
Construction and Building Materials
Summary
Timber–concrete composites (TCC) are smart solutions for slabs in residential and office buildings regarding the sustainable and performance-optimized use of materials. However, a non-negligible disadvantage is the deflection of the timber elements caused by in-situ concrete casting during construction. This paper presents an approach to camber timber elements without external forces by using the innate swelling capacity of wood. Oven-dried hardwood inlays can be inserted transversally into cuts on the top side of a timber element. After an increase of the moisture content in the inlays, the swelling pressure will result in a self-camber of the timber element. In this study, a procedure for prediction of the self-camber is derived and the model is validated using an experimental test series. The results demonstrate that the self-camber of spruce elements using beech inlays is both feasible and predictable. On this basis, practical application scenarios for TCC elements in timber engineering are shown and discussed.
Online Access
Free
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Vertical Movement in Wood Platform Frame Structures: Movement Prediction

https://research.thinkwood.com/en/permalink/catalogue737
Year of Publication
2013
Topic
Serviceability
Moisture
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Doudak, Ghasan
Lepper, Peggy
Ni, Chun
Wang, Jasmine
Organization
Canadian Wood Council
FPInnovations
Year of Publication
2013
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Serviceability
Moisture
Keywords
Moisture Content
Shrinkage
Swelling
Adhesives
Differential Movement
Research Status
Complete
Summary
It is not possible or practical to precisely predict the vertical movement of wood structures due to the many factors involved in construction. It is, however, possible to obtain a good estimate of the vertical movement to avoid structural, serviceability, and building envelope problems over the life of the structure. Typically “S-Dry” and “S-Grn” lumber will continue to lose moisture during storage, transportation and construction as the wood is kept away from liquid water sources and adapts to different atmospheric conditions. For the purpose of shrinkage prediction, it is usually customary to assume an initial moisture content (MC) of 28% for “S-Green” lumber and 19% for “S-Dry” lumber. “KD” lumber is assumed to have an initial MC of 15% in this series of fact sheets. Different from solid sawn wood products, Engineered Wood Products (EWP) are usually manufactured with MC levels close to or even lower than the equilibrium moisture content (EMC) in service. Plywood, Oriented Strand Board (OSB), Laminated Veneer Lumber (LVL), Laminated Strand Lumber (LSL), and Parallel Strand Lumber (PSL) are usually manufactured at MC levels ranging from 6% to 12%. Engineered wood I-joists are made using kiln dried lumber (usually with moisture content below 15%) or structural composite lumber (such as LVL) flanges and plywood or OSB webs, therefore they are usually drier and have lower shrinkage than typical “S-Dry” lumber floor joists. Glued-laminated timbers (Glulam) are manufactured at MC levels from 11% to 15%, so are the recently-developed Cross-laminated Timbers (CLT). For all these products, low shrinkage can be achieved and sometimes small amounts of swelling can be expected in service if their MC at manufacturing is lower than the service EMC. In order to fully benefit from using these dried products including “S-Dry” lumber and EWP products, care must be taken to prevent them from wetting such as by rain during shipment, storage and construction. EWPs may also have lower shrinkage coefficients than solid wood due to the adhesives used during manufacturing and the more mixed grain orientations in the products, including the use of cross-lamination of veneers (plywood) or lumber (CLT). The APEGBC Technical and Practice Bulletin emphasizes the use of EWP and dimension lumber with 12% moisture content for the critical horizontal members to reduce differential movement in 5 and 6-storey wood frame buildings.
Online Access
Free
Resource Link
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6 records – page 1 of 1.