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Finite Element Modelling of Moisture Related and Visco-Elastic Deformations in Inhomogeneous Timber Beams

https://research.thinkwood.com/en/permalink/catalogue425
Year of Publication
2013
Topic
Mechanical Properties
Moisture
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Ormarsson, Sigurdur
Dahlblom, Ola
Publisher
ScienceDirect
Year of Publication
2013
Country of Publication
Netherlands
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Moisture
Keywords
Inhomogeneous
Finite Element Model
Axial Deformation
Lateral Deformation
Shrinkage
Mechanosorption
Visco-Elastic
Language
English
Research Status
Complete
Series
Engineering Structures
Summary
Wood is a hygro-mechanical, non-isotropic and inhomogeneous material concerning both modulus of elasticity (MOE) and shrinkage properties. In stress calculations associated with ordinary timber design, these matters are often not dealt with properly. The main reason for this is that stress distributions in inhomogeneous glued laminated members (glulams) and in composite beams exposed to combined mechanical action and variable climate conditions are extremely difficult to predict by hand. Several experimental studies of Norway spruce have shown that the longitudinal modulus of elasticity and the longitudinal shrinkage coefficient vary considerably from pith to bark. The question is how much these variations affect the stress distribution in wooden structures exposed to variable moisture climate. The paper presents a finite element implementation of a beam element with the aim of studying how wooden composites behave during both mechanical and environmental load action. The beam element is exposed to both axial and lateral deformation. The material model employed concerns the elastic, shrinkage, mechano-sorption and visco-elastic behaviour of the wood material. It is used here to simulate the behaviour of several simplysupported and continuous composite beams subjected to both mechanical and environmental loading to illustrate the advantages this can provide. The results indicate clearly both the inhomogeneity of the material and the variable moisture action occurring to have had a significant effect on the stress distribution within the cross-section of the products that were studied.
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FE Analysis of CLT Panel Subjected to Torsion and Verified by DIC

https://research.thinkwood.com/en/permalink/catalogue485
Year of Publication
2013
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Sebera, Václav
Muszynski, Lech
Tippner, Jan
Noyel, Melanie
Pisaneschi, Thomas
Sundberg, Benjamin
Publisher
Springer Netherlands
Year of Publication
2013
Country of Publication
Netherlands
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Finite Element Model
Torsion
Numerical model
Digital Image Correlation
Language
English
Research Status
Complete
Series
Materials and Structures
ISSN
1871-6873
Summary
The goal of this study was to analyze behavior of the cross-laminated timber (CLT) panel subjected to torsion and develop an efficient procedure for quick verification of numerical model of CLT that subsequently may be used for virtual prototyping of non-standard CLT products. Study used both experiments based on optical measurement using digital image correlation (DIC) and numerical modeling by means of finite element method (FEM). A physical torsion test of the CLT panel was first analyzed in terms of a displacement field that was computed on its surface. The FE simulation of the torsion test followed real boundary conditions and was carried out with use of 2 geometrically different FE models of the CLT. The first FE model did not take into account edgebonding of the lamellas, the second one demonstrated alternative manufacturing option by considering the lamellas’ edge-bonding. The experiment and FE simulations were mutually compared based on displacement paths created on the panel surface. Results showed that the presented procedure offers relatively easy way of verification of FE analyses of CLT. FE model with edge-bonding of lamellas exhibited higher stiffness and higher relative error to DIC measurement than FE model without edge-bonding. Edge-bonding of lamellas introduces influential factor in FE modeling of CLT and should be omitted for accurate and realistic FE analyses of their behavior. Study also showed that lack of orthotropic properties of Oregon hybrid poplar can be in FEA sufficiently substituted by using cottonwood properties. Combining the DIC measurement and FEM in the analysis of the CLT is favorable since it offers an full-field validation of numerical models, which can be subsequently used for virtual prototyping.
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In Situ Measured Flanking Transmission in Light Weight Timber Houses with Elastic Flanking Isolators

https://research.thinkwood.com/en/permalink/catalogue231
Year of Publication
2013
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Wood Building Systems
Author
Ågren, Anders
Ljunggren, Fredrik
Organization
Inter-noise
Year of Publication
2013
Country of Publication
Austria
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Floors
Wood Building Systems
Topic
Acoustics and Vibration
Keywords
Modules
Prefabrication
Sound Insulation
Elastomer Isolators
Language
English
Conference
Inter-noise 2013
Research Status
Complete
Notes
September 15-18, 2013, Innsbruck, Austria
Summary
There is a strong trend to industrially produce multi-storey light weight timber based houses. This concept allows the buildings to be manufactured to a more or less prefabricated extent. Most common types are volume/room modules or flat wall and floor modules. When assembling the modules at the building site, elastomer isolators are used in several constructions to reduce flanking transmission. The sound insulation demands in the Nordic countries are relatively high and therefore the flanking transmission must be well controlled, where elastomer isolators are an alternative. Decoupled radiation isolated walls is another. There are though no working studies or mathematical models of the performance of these isolators. They are only treated as simple mass-springs systems that operate vertically, i.e. one degree of freedom. In this paper there is an analysis of experimentally data of the structure borne sound isolating performance of elastomer isolators that are separating an excited floor from receiving walls. The performance dependence of structure type is also presented. An empirically based regression model of the vibration level difference is derived. The model is based on measurements of six elastomer field installations, which are compared to five comparable installations without elastomers. A goal is that the model can be used for input in future SEN prediction models for modeling of sound insulation.
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Prediction of Bending Stiffness and Moment Carrying Capacity of Sugi Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue604
Year of Publication
2013
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Okabe, Minoru
Yasumura, Motoi
Kobayashi, Kenji
Fujita, Kazuhiko
Publisher
Springer Japan
Year of Publication
2013
Country of Publication
Japan
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Mechanical Properties
Keywords
Bending Stiffness
Moment Carrying Capacity
Monte Carlo
Modulus of Elasticity
Language
English
Research Status
Complete
Series
Journal of Wood Science
ISSN
1611-4663
Summary
Cross-laminated timber (CLT) panels consist of several layers of lumber stacked crosswise and glued together on their faces. Prototype sugi CLT floor panels were manufactured and bending tests were carried out under the different parameters of lumber modulus of elasticity (MOE), number of layers, thickness of lumber and thickness of CLT panels. On the basis of above tests, bending stiffness and moment carrying capacity were predicted by Monte Carlo method. MOE of lumber was measured by using grading machine and tensile strength of lumber was assumed to be 60 % of bending strength based on the obtained bending test. Bending stiffness EI of CLT panels could be estimated by adopting composite theory and equivalent section area. Experimental moment carrying capacity showed 12 % higher value than the calculated moment carrying capacity by average lumber failure method, and also showed 45 % higher value than the calculated moment carrying capacity by minimum lumber failure method due to the reinforcement of the outer layer by the neighboring cross layer.
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Experimental Analysis of the Structural Behavior of Timber-Concrete Composite Slabs Made of Beech-Laminated Veneer Lumber

https://research.thinkwood.com/en/permalink/catalogue611
Year of Publication
2013
Topic
Connections
Mechanical Properties
Material
Timber-Concrete Composite
LVL (Laminated Veneer Lumber)
Application
Floors
Author
Boccadoro, Lorenzo
Frangi, Andrea
Publisher
American Society of Civil Engineers
Year of Publication
2013
Country of Publication
United States
Format
Journal Article
Material
Timber-Concrete Composite
LVL (Laminated Veneer Lumber)
Application
Floors
Topic
Connections
Mechanical Properties
Keywords
Beech
Spruce
Load Carrying Capacity
Structural Behavior
Failure Modes
Notch Connections
Language
English
Research Status
Complete
Series
Journal of Performance of Constructed Facilities
Summary
The wood engineering community has dedicated a significant amount of effort over the last decades to establish a reliable predictive model for the load-carrying capacity of timber connections under wood failure mechanisms. Test results from various sources (Foschi and Longworth 1975; Johnsson 2003; Quenneville and Mohammad 2000; Stahl et al. 2004; Zarnani and Quenneville 2012a) demonstrate that for multi-fastener connections, failure of wood can be the dominant mode. In existing wood strength prediction models for parallel to grain failure in timber connections using dowel-type fasteners, different methods consider the minimum, maximum or the summation of the tensile and shear capacities of the failed wood block planes. This results in disagreements between the experimental values and the predictions. It is postulated that these methods are not appropriate since the stiffness in the wood blocks adjacent to the tensile and shear planes differs and this leads to uneven load distribution amongst the resisting planes (Johnsson 2004; Zarnani and Quenneville 2012a). The present study focuses on the nailed connections. A closed-form analytical method to determine the load-carrying capacity of wood under parallel-to-grain loading in small dowel-type connections in timber products is thus proposed. The proposed stiffness-based model has already been verified in brittle and mixed failure modes of timber rivet connections (Zarnani and Quenneville 2013b).
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Vertical Movement in Wood Platform Frame Structures: Design and Detailing Solutions

https://research.thinkwood.com/en/permalink/catalogue736
Year of Publication
2013
Topic
Serviceability
Material
Light Frame (Lumber+Panels)
Application
Wood Building Systems
Author
Doudak, Ghasan
Lepper, Peggy
Ni, Chun
Wang, Jasmine
Organization
Canadian Wood Council
FPInnovations
Year of Publication
2013
Country of Publication
Canada
Format
Report
Material
Light Frame (Lumber+Panels)
Application
Wood Building Systems
Topic
Serviceability
Keywords
Differential Movement
Language
English
Research Status
Complete
Summary
Most buildings are designed to accommodate a certain range of movement. In design, it is important for designers to identify locations where potential differential movement could affect structural integrity and serviceability, predict the amount of differential movement and develop proper detailing to accommodate it. To allow non-structural materials to be appropriately constructed, estimate of anticipated differential movement should be provided in the design drawings. Simply specifying wood materials with lower MC at time of delivery does not guarantee that the wood will not get wet on construction sites and will deliver lower shrinkage amounts as anticipated. It is therefore important to ensure that wood does not experience unexpected wetting during storage, transportation and construction. Good construction sequencing also plays an important role in reducing wetting, the consequent wood shrinkage and other moisture-related issues. Existing documents such as the APEGBC Technical and Practice Bulletin on 5- and 6-Storey Wood Frame Residential Building Projects, the Best Practice Guide published by the Canadian Mortgage and Housing Corporation (CMHC), the Building Enclosure Design Guide – Wood Frame Multi-Unit Residential Buildings published by the BC Housing- Homeowner Protection Office (HPO) provide general design guidance on how to reduce and accommodate differential movement in platform frame construction.
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Proposal of Design Method for Wood - Concrete Composite Beams Part 2 : Experimental Study on Creep Behavior

https://research.thinkwood.com/en/permalink/catalogue873
Year of Publication
2013
Topic
Design and Systems
Mechanical Properties
Material
Timber-Concrete Composite
Application
Beams
Author
Suzuki, Sota
Goto, Hiroshi
Inama, Masahiro
Ken, Kamike
Kitamura, Toshio
Yanagi, Sayaka
Organization
Architectural Institute of Japan
Year of Publication
2013
Country of Publication
Japan
Format
Journal Article
Material
Timber-Concrete Composite
Application
Beams
Topic
Design and Systems
Mechanical Properties
Keywords
Creep
Language
Japanese
Research Status
Complete
Summary
High strength, low weight, corrosion resistance, and electromagnetic neutrality make fiber-reinforced plastic (FRP) a suitable candidate in many structural applications, including rehabilitation and strengthening as well as the development of new wood members. Advanced forms of reinforced wood construction can enable contemporary wood structures to play an even greater role in today's construction."In this work, the writers establish a novel technique for reinforcing wood members involving external bonding of pretensioned FRP sheets on their tension zones. An analytical model for the maximum initial pretension is verified with tests on carbon/epoxy-prestressed wood beams. Additional studies, both analytical and experimental of the flexural behavior of wood beams reinforced with prestressed carbon/epoxy FRP sheets demonstrate the superior performance of the hybrid system and emphasize its favorable strength, stiffness, and ductility characteristics. Finally, a methodology is described for the selection of composite material dimensions and initial prestressing to maximize structural performance.
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CLT Infill Panels in Steel Moment Resisting Frames as a Hybrid Seismic Force Resisting System

https://research.thinkwood.com/en/permalink/catalogue107
Year of Publication
2013
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Dickof, Carla
Organization
University of British Columbia
Year of Publication
2013
Country of Publication
Canada
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Seismic
Keywords
National Building Code of Canada
Timber-Steel Hybrid
Seismic Force Resisting System
Language
English
Research Status
Complete
Summary
This paper examines CLT-steel hybrid systems at three, six, and nine storey heights to increase seismic force resistance compared to a plain wood system. CLT panels are used as infill in a steel moment frame combining the ductility of a steel moment frame system with a stiffness and light weight of CLT panels. This system allows for the combination of high strength and ductility of steel with high stiffness and light weight of timber. This thesis examines the seismic response of this type of hybrid seismic force resisting system (SFRS) in regions with moderate to high seismic hazard indices. A detailed non-linear model of a 2D infilled frame system and compared to the behavior of a similar plain steel frame at each height. Parametric analysis was performed determining the effect of the panels and the connection configuration, steel frame design, and panel configuration in a multi-bay system. Static pushover loading was applied alongside semi-static cyclic loading to allow a basis of comparison to future experimental tests. Dynamic analysis using ten ground motions linearly scaled to the uniform hazard spectra for Vancouver, Canada with a return period of 2% in 50 years as, 10% in 50 years, and 50% in 50 years to examine the effect of infill panels on the interstorey drift of the three, six, and nine storey. The ultimate and yield strength and drift capacity are determined and used to determine the overstrength and ductility factors as described in the National Building Code of Canada 2010.
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Development of Evaluation Methodology for Rolling Shear Properties in Cross Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue137
Year of Publication
2013
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Beams
Author
Zhou, Qinyi
Organization
University of New Brunswick
Year of Publication
2013
Country of Publication
Canada
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Span-to-Depth
Rolling Shear Modulus
Two-plate shear test
Load Carrying Capacity
Language
English
Research Status
Complete
Summary
The rolling shear modulus is very low, leading to rolling shear failure in the cross layer of cross-laminated timber (CLT). The overall objective of this thesis work was to develop an appropriate methodology for measuring the rolling shear properties of CL T. This research consists of three article format chapters, which were aimed at: 1) obtaining a better understanding of advantages and disadvantages of using the bending test and twoplate shear test for determining the rolling shear properties of 3-layer CLT, 2) investigating the influence of growth ring orientation and laminates thickness of cross layer on the rolling shear properties, and 3) verifying the feasibility of two-plate shear test method for measuring the rolling shear properties of 3-layer CL T beam. It is recommended that the two-plate shear test be used as a testing method for measuring the rolling shear modulus of a cross layer, which can be used to calculate the deflection of a 3-layer CLT beam using the shear analogy method at a given span-to-depth ratio ranging from 6 to 50. An adjustment factor (a) was proposed to predict the deflection under the centre-point bending test at various span-to-depth ratios. The two-plate shear test method can also be used to measure the rolling shear strength, and can provide a reasonable estimate of the load-carrying capacity of 3-layer CLT beam at a relatively large span-to-depth ratio, but a conservative estimate at a small span-to-depth ratio. In summary, it shall be feasible to adopt the two-plate shear test for determining the rolling shear modulus and strength of cross layer in CLT.
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In Plane Shear Strength of Cross Laminated Timber (CLT): Test Configuration, Quantification and influencing Parameters

https://research.thinkwood.com/en/permalink/catalogue2121
Year of Publication
2013
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems

10 records – page 1 of 1.