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16 records – page 1 of 2.

An Algorithm for Numerical Modelling of Cross-Laminated Timber Structures

https://research.thinkwood.com/en/permalink/catalogue2362
Year of Publication
2015
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
D'Aronco, Gabriele
Publisher
Università di Padova
Year of Publication
2015
Country of Publication
Italy
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Keywords
Connections
Panels
Model
Language
English
Research Status
Complete
Summary
Cross-laminated timber, also known as X-Lam or CLT, is well established in Europe as a construction material. Recently, implementation of X-Lam products and systems has begun in countries such as Canada, United States, Australia and New Zealand. So far, no relevant design codes for X-Lam construction were published in Europe, therefore an extensive research on the field of cross-laminated timber is being performed by research groups in Europe and overseas. Experimental test results are required for development of design methods and for verification of design models accuracy. This thesis is part of a large research project on the development of a software for the modelling of CLT structures, including analysis, calculation, design and verification of connections and panels. It was born as collaboration between Padua University and Barcelona"s CIMNE (International Centre for Numerical Methods in Engineering). The research project started with the thesis “Una procedura numerica per il progetto di edifici in Xlam” by Massimiliano Zecchetto, which develops a software, using MATLAB interface, only for 2D linear elastic analysis. Follows the phase started in March 2015, consisting in extending the 2D software to a 3D one, with the severity caused by modelling in three dimensions. This phase is developed as a common project and described in this thesis and in “Pre-process for numerical analysis of Cross Laminated Timber Structures” by Alessandra Ferrandino. The final aim of the software is to enable the modelling of an X-Lam structure in the most efficient and reliable way, taking into account its peculiarities. Modelling of CLT buildings lies into properly model the connections between panels. Through the connections modelling, the final aim is to enable the check of preliminarily designed connections or to find them iteratively, starting from hypothetical or random connections. This common project develops the pre-process and analysis phases of the 3D software that allows the automatic modelling of connections between X-Lam panels. To achieve the goal, a new problem type for GiD interface and a new application for KRATOS framework have been performed. The problem type enables the user to model a CLT structure, starting from the creation of the geometry and the assignation of numeric entities (beam, shell, etc.) to geometric ones, having defined the material, and assigning loads and boundary conditions. The user does not need to create manually the connections, as conversely needs for all commercial FEM software currently available; he just set the connection properties to the different sides of the panels. The creation of the connections is made automatically, keeping into account different typologies of connections and assembling of Cross-Lam panels. The problem type is special for XLam structures, meaning that all features are intentionally studied for this kind of structures and the software architecture is planned for future developments of the postprocess phase. It can be concluded that sound bases for the pre-process and analysis phases of the software have been laid. However, future research is required to develop the postprocess and verification phases of the research project.
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Free
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Damping in Timber Structures

https://research.thinkwood.com/en/permalink/catalogue106
Year of Publication
2012
Topic
Design and Systems
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Floors
Beams

Dynamic Response of Cross Laminated Timber Floors Subject to Internal Loads

https://research.thinkwood.com/en/permalink/catalogue2716
Year of Publication
2020
Topic
Design and Systems
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Skoglund, Jacob
Publisher
Lund University
Year of Publication
2020
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Design and Systems
Mechanical Properties
Keywords
Internal Loads
Finite Element Method (FEM)
Panels
Seven-Layer Model
Modal Analysis
3D Model
2D Model
Language
English
Research Status
Complete
Summary
The deregulation of timber for use in large scale constructions has seen the addition of new innovative timber-based products to a category of products referred to as engineered wood products. A now well established addition to these products is cross laminated timber, or CLT for short. CLT products use a form of orthogonal layering, where several parallel wooden boards are arranged in a number of layers, each layer being orthogonal to the previous. The use of orthogonal layering allows for increased stiffness in the two plane directions, resulting in a lightweight construction product with high load bearing capacity and stiffness. To evaluate the dynamic behaviour of structures, engineers commonly apply the finite element method, where a system of equations are solved numerically. Given a sufficient amount of computational power and time, the finite element method can help to solve most dynamical problems. For sufficiently large or complex structures the amount of resources needed may be outside the scope of possibility or feasibility for many. Therefore, evaluating the usage of certain design simplifications, such as omitting to models aspects of the geometry, or alternative forms of analysis for CLT panels may help to reduce the time and resources required for an analysis. In this Master's dissertation, a seven-layer CLT-panel has been created. In the model, each individual board and the gaps between the boards are modelled. The seven-layer model is used as a reference to evaluate the possibility of using less detailed alternative models. The alternative models are created as a layered 3D model and a composite 2D model, both models omit the modelling of the individual laminations, resulting in the layers being solid. The results show small errors for the alternative models when using modal analysis. Concluding that the modal behaviour and dynamic response of a CLT panel can be evaluated using a composite 2D model or a less-detailed layered 3D model. This significantly reduces the amount of time and computational power needed for an analysis, and clearly indicates the benefit of using alternative less detailed models.
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Free
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Effects of Heavy Topping on Vibrational Performance of Cross-Laminated Timber Floor Systems

https://research.thinkwood.com/en/permalink/catalogue2708
Year of Publication
2020
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Schwendy, Benjamin
Publisher
Clemson University
Year of Publication
2020
Country of Publication
United States
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Vibration Serviceability
Concrete Topping
Panels
Insulation
Language
English
Research Status
Complete
Summary
Cross-Laminated Timber (CLT) is gaining momentum as a competitor to steel and concrete in the construction industry. However, with CLT being relatively new to North America, it is being held back from realizing its full potential by a lack of research in various areas, such as vibration serviceability. This has resulted in vague design guidelines, leading to either overly conservative designs, hurting profit margins, or leading to overly lenient designs, resulting in occupancy discomfort. Eliminating these design inefficiencies is paramount to expanding the use of CLT and creating a more sustainable construction industry. This thesis focuses on the effect of a heavy topping, in this case 2" of concrete over a layer of rigid insulation, on a CLT floor. To this end, modal analysis was performed on two spans of three CLT panels in the Andy Quattlebaum Outdoor Education Center at Clemson University. By performing a series of instrumented heel-drop tests with a roving grid of accelerometers, the natural frequencies, mode shapes, frequency response functions, and damping coefficients were determined. By comparing the results to several different numerical models, the most appropriate model was selected for use in future design. In addition, a walking excitation test was performed to calculate the root mean square acceleration of the floor for comparison to current design standards. This study found that, with a layer of rigid insulation separating the topping and the panel, the system behaved predictably like a non-composite system. The resultant mode shapes also verified that the boundary conditions behaved very close to “hinged” and showed that the combination of the surface splines and the continuous topping provide significant transverse continuity in terms of response to vibrations. Lastly, the results of the walking excitation test showed that, with some further study, the current design standards for steel vibration serviceability can be applied to great effect to CLT systems.
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Evaluation of the Bonding Quality of E. grandis Cross-Laminated Timber Made With a One-Component Polyurethane Adhesive

https://research.thinkwood.com/en/permalink/catalogue2369
Year of Publication
2018
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Dugmore, Michael
Publisher
Stellenbosch University
Year of Publication
2018
Country of Publication
South Africa
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Keywords
Polyurethane
Panels
Bond Performance
Bond Quality
Durability Assessment
Language
English
Research Status
Complete
Summary
Eucalyptus grandis is South Africa‘s most important commercial hardwood species. The availability of E. grandis and its fast growth rate creates the opportunity to explore its uses further. Cross-laminated timber (CLT) is a prefabricated multilayer engineered panel product made of at least three layers, with the grain direction of some or all of the consecutive layers orthogonally orientated. In order to add value to E. grandis, reduce the export of low-cost chips, increase the profit margins of local plantation owners and create jobs, the development of E. grandis CLT in South Africa may be an option. There is concern among some researchers that the bonding quality evaluation tests proposed by CLT standards have been developed for glulam and are too severe for CLT. These researchers proposed that further analysis and possibly even revision of the test methods should be considered. There is also a need to evaluate the mechanical properties of CLT panels made of E. grandis to completely understand the structural performance of these panels, including their bond quality and durability, and therefore be able to rely on E. grandis CLT as a construction material. The objectives of this study were: . To evaluate the face-bonding quality of CLT panels from E. grandis timber bonded with a one component polyurethane resin; . To determine the influence of material and processing parameters on the face-bonding quality of CLT manufactured from E. grandis timber bonded with a one component polyurethane resin; . To analyse different testing methods for evaluating the face-bonding quality of CLT. The design for this experiment consisted of eight groups with different combinations of parameters for density, grooves and pressure per group. Four different testing methods were used to evaluate the face-bonding quality of CLT panels from E. grandis and to determine the effect of parameters on face-bonding quality: A delamination test on 100 x 100 mm block specimens (Test A), a shear test on 40 x 40 mm specimens (Test B), a shear test on 40 x 40 mm specimens with grain direction 45° to load direction (Test C) and a combined delamination and shear test on 70 x 70 mm specimens with grain direction 45° to load direction (Test D). Results of the statistical analysis indicated that E. grandis CLT made with 1C-PUR adhesive can obtain excellent face-bonding quality using a clamping pressure of 0.7 MPa and with no stress relief grooves present. All samples passed the shear test (Test B) which is the reference test method proposed by EN 16351 (2015). It was found that a strength component and durability component will be an advantage when testing the bond quality of CLT. Shear tests at 45° to the load direction did not completely eliminate the rolling shear effect. The combined delamination and shear test (Test D), seems to have potential as a good test for bond quality since it is a combination of a durability and shear strength test. There are still questions about the relative advantages of specific test methods for bond quality, especially on the effect of rolling shear. Further work should focus on this aspect and the use of stress models might be a way of gaining further insights.
Online Access
Free
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Examination of the Lateral Resistance of Cross-Laminated Timber in Panel-Panel Connections

https://research.thinkwood.com/en/permalink/catalogue2302
Year of Publication
2015
Topic
Design and Systems
Connections
Material
CLT (Cross-Laminated Timber)
Application
Walls
Wood Building Systems
Author
Richardson, Benjamin Lee
Publisher
Virginia Tech
Year of Publication
2015
Country of Publication
United States
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Walls
Wood Building Systems
Topic
Design and Systems
Connections
Keywords
Lateral Resistance
Shear Resistance
Full Scale
Panels
Small Scale
Steel Connections
Language
English
Research Status
Complete
Online Access
Free
Resource Link
Less detail

Exploratory Study of Salvaged Lumber as Feedstock for Cross-Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue2278
Year of Publication
2019
Topic
Mechanical Properties
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems

Exploring Cross-Laminated Timber Use for Temporary Military Structures: Ballistic Considerations

https://research.thinkwood.com/en/permalink/catalogue2371
Year of Publication
2018
Topic
Design and Systems
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Sanborn, Kathryn
Publisher
Georgia Institute of Technology
Year of Publication
2018
Country of Publication
United States
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Market and Adoption
Keywords
Ballistic Resistance
Panels
Military Structures
Blast Analysis Tool
Spruce-Pine-Fir
Southern Pine
SPF
Language
English
Research Status
Complete
Summary
The design and construction of temporary military structures has changed little since World War II. While these structures are lightweight and rapidly deployable, they require a sizeable workforce to construct and provide minimal ballistic and blast protection for occupants. Cross-laminated timber (CLT) is a relatively new prefabricated engineered wood product that is strong, stiff, quick to build, and has the potential to offer inherent ballistic and blast resistance compared to traditional wood products. The orthotropic nature of CLT coupled with the energy absorbing capacity of the thick wood panels warrant further investigation into the viability of CLT for temporary military structures. To that end, the research presented in this thesis seeks to better understand the ballistic and blast response of CLT panels and to develop evaluation criteria for the use of CLT in temporary military structures. Specific areas of investigation included: 1) experimental testing of the ballistic resistance of CLT panels, conducting in conjunction with U.S. Army laboratories in Aberdeen Proving Grounds, Maryland and Vicksburg, Mississippi; 2) the design, prototyping, and experimental testing of enhanced CLT panels to further improve ballistic performance; 3) a qualitative analysis of CLT panels under ballistic impact resistance mechanisms; 4) the development of a CLT blast analysis tool to predict the elastic response of CLT to blast loadings; and 5) the development of a simplified tool to identify evaluation criteria for temporary military structure material selection, including conventional materials as well as CLT. Specimens in this research consisted of commercially produced Spruce-Pine-Fir CLT as well as Southern Pine CLT specimens fabricated specifically for this research. Ballistic testing of both types of conventional CLT indicate that the material’s inherent penetration resistance is significantly greater than that of dimension lumber and plywood used in current common temporary military structures. The testing shows that current U.S. military design guidelines (UFC 4-023-07), used for determining required wood thickness based on ballistic threat, under predicts the ballistic performance of CLT. From testing and analysis, the thesis develops updated equations for predicting the thickness of CLT required for ballistic protection. A qualitative analysis of ballistic specimens identified local failure modes in the CLT and links the observed damage the anisotropic material properties, grading, and defects in sawn timbers. Enhanced CLT specimens were fabricated using various hardening materials including thin metal plates and gratings, polymer-based armors, and fiber-reinforced epoxy matrix panels. The enhanced CLTs were evaluated based on ease of production, ballistic resistance as compared to conventional CLT, and cost-benefit analysis. The shear analogy method was incorporated into a single-degree-of-freedom blast analysis to predict the response of different types and sizes of CLT panels under blast loads within the elastic regime. The tool was validated using field data from low-level live blast tests and showed good agreement with the field data. Finally, tailored evaluation criteria for comparative assessment of construction materials for use in temporary military structures – considering issues of cost, the logistics of in-theater deployment, energy consumption and force protection were developed and applied through using the AHP decision-making process.
Online Access
Free
Resource Link
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Fire Resistance of Partially Protected Cross-Laminated Timber Rooms

https://research.thinkwood.com/en/permalink/catalogue322
Year of Publication
2015
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls

Hygrothermal Properties of Cross Laminated Timber Panels

https://research.thinkwood.com/en/permalink/catalogue2307
Year of Publication
2017
Topic
Moisture
Material
CLT (Cross-Laminated Timber)
LSL (Laminated Strand Lumber)
Application
Walls
Wood Building Systems
Author
Tripathi, Jaya
Publisher
University of Maine
Year of Publication
2017
Country of Publication
United States
Format
Thesis
Material
CLT (Cross-Laminated Timber)
LSL (Laminated Strand Lumber)
Application
Walls
Wood Building Systems
Topic
Moisture
Keywords
Panels
Heat Transfer
Thermal Conductivity
Humidity
Moisture Transfer
Spruce
Language
English
Research Status
Complete
Online Access
Free
Resource Link
Less detail

16 records – page 1 of 2.