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Cross Laminated Timber (CLT) – Reinforcements with Self-Tapping Screws

https://research.thinkwood.com/en/permalink/catalogue1487
Year of Publication
2010
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Mestek, Peter
Winter, Stefan
Year of Publication
2010
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Concentrated Loads
Self-Tapping Screws
FEM
Rolling Shear Stress
Compression
Strengthening
Load Bearing
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
June 20-24, 2010, Riva del Garda, Italy
Summary
This paper illustrates a research project about the calculation and design of Cross Laminated Timber (CLT) elements stressed by concentrated loads. Its focus lies on the shear design of CLT-elements next to punctual supports including reinforcements with self-tapping screws with continuous threads in areas of high shear stresses. Different influencing parameters on the distribution of shear forces next to a punctual support were evaluated by using comparative FEM-analyses. In the course of laboratory tests material-mechanical principles were determined to consider the interaction of rolling shear stresses and compression perpendicular to the grain. In addition to FEM simulations several experimental tests were carried out to describe the load bearing behaviour and the strengthening effect of CLT-elements reinforced by self-tapping screws. The investigations aim at developing a design concept including the effects mentioned above.
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Structural Performance of Box Based Cross Laminated Timber System Used in Floor Applications

https://research.thinkwood.com/en/permalink/catalogue1171
Year of Publication
2011
Topic
Mechanical Properties
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Chen, Yue
Organization
University of British Columbia
Year of Publication
2011
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Mechanical Properties
Acoustics and Vibration
Keywords
Three Point Bending Test
Vertical Deflection
Bending Stiffness
Fundamental Frequency
Finite Element Analysis
Research Status
Complete
Summary
The current outbreak of Mountain Pine Beetle (MPB) in the province of British Columbia (B.C.) is the most extensive disturbance event occurring in North American forests in recorded history. The concept of converting the beetle killed wood into engineered wood products by defect removal and reconstitution is employed to maximize value recovery from the material. Cross Laminated Timber (CLT), which is produced in modular form and can be utilized as part of a structural system for floor, wall or roof elements, is considered as an excellent application of the concept. CLT originates from Europe. Such products have been developed as a proprietary product by individual companies aimed at servicing specific markets. There is a need to investigate different ways of making CLT and to define its structural performance suitable for North America. The main focus of this study is to investigate the structural performance of box based CLT system used in floor applications. Comprehensive three dimensional finite element models, which can be used to analyze the mechanical and vibration behavior of the plate and box type structures, were developed. Four prototype box elements, each having five replicates, were designed and manufactured locally. Third point bending tests were conducted on the specimens in the Timber Engineering and Applied Mechanics (TEAM) Laboratory at the University of British Columbia. The numerical analysis agreed well with experimental data in terms of vertical deflection and bending stiffness. Vibration, which is critical to floor serviceability, was also studied. Three types of excitation were applied to measure the fundamental frequency of the twenty specimens. Finite element analysis provided good predictions of fundamental frequency values comparing to the experimental results. A local built demonstration building, L41home, was presented and analyzed as an example using the tools developed in this study for CLT applications. As a pioneer research of CLT materials in North America, this work has contributed to the understanding of the structural performance of floor systems using CLT panels for the commercial and residential applications.
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Investigating the Performance of Wood Portal Frames as Alternative Bracing Systems in Light-Frame Wood Buildings

https://research.thinkwood.com/en/permalink/catalogue2240
Year of Publication
2012
Topic
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
LSL (Laminated Strand Lumber)
Application
Frames
Author
Al Mamun, Abdullah
Organization
University of Ottawa
Year of Publication
2012
Format
Thesis
Material
LVL (Laminated Veneer Lumber)
LSL (Laminated Strand Lumber)
Application
Frames
Topic
Mechanical Properties
Keywords
Portal Frames
Shear Walls
FE model
Moment Capacity
Stiffness
Lateral Load
Research Status
Complete
Summary
Light-frame shearwall assemblies have been successfully used to resist gravity and lateral loads, such as earthquake and wind, for many decades. However, there is a need for maintaining the structural integrity of such buildings even when large openings in walls are introduced. Wood portal frame systems have been identified as a potential alternative to meet some aspects of this construction demand. The overarching goal of the research is to develop wood portal frame bracing systems, which can be used as an alternative or in combination with light-frame wood shearwalls. This is done through investigating the behavior of wood portal frames using the MIDPLY shearwall framing technique. A total of 21 MIDPLY corner joint tests were conducted with varying bracing details. Also, a finite element model was developed and compared with test results from the current study as well as studies by others. It was concluded from the corner joint tests that the maximum moment resistance increased with the addition of metal straps or exterior sheathings. The test results also showed a significant increase in the moment capacity and rotational stiffness by replacing the Spruce-Pine Fir (SPF), header with the Laminated Veneer Lumber (LVL) header. The addition of the FRP to the standard wall configuration also resulted in a significant increase in the moment capacity. However, no significant effect was observed on the stiffness properties of the corner joint. The FE model was capable of predicting the behavior of the corner joints and the full-scale portal frames with realistic end-conditions. The model closely predicted the ultimate lateral capacity for all the configurations but more uncertainty was found in predicting the initial stiffness.The FE model used to estimate the behavior of the full-scale portal frames constructed using the MIDPLY framing techniques showed a significant increase in the lateral load carrying capacity when compared with the traditional portal frame. It was also predicted using the full-scale FE model that the lateral load carrying capacity of the MIDPLY portal frame would increase with the addition of the metal straps on exterior faces. A parametric study showed that using a Laminated Strand Lumber (LSL) header increased the lateral load carrying capacity and the initial stiffness of the frames relative to the SPF header. The study also showed that there was an increase in the capacity if high strength metal straps were used. Doubling of the nail spacing at header and braced wall segment had a considerable effect on the lateral capacity of portal frame. Also, the initial stiffness was reduced for all the configurations with the doubling of the nail spacing at the header and braced wall segment in comparison with the reference frame.
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Experimental-Numerical Analyses of the Seismic Behaviour of Cross-Laminated Wall Systems

https://research.thinkwood.com/en/permalink/catalogue56
Year of Publication
2012
Topic
Seismic
Energy Performance
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Gavric, Igor
Rinaldin, Giovanni
Amadio, Claudio
Fragiacomo, Massimo
Ceccotti, Ario
Year of Publication
2012
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Seismic
Energy Performance
Keywords
Finite Element Model
Abaqus
Experimental
Numerical
Full Scale
Cyclic Testing
Conference
World Conference on Earthquake Engineering
Research Status
Complete
Notes
September 24-28, 2012, Lisbon, Portugal
Summary
The paper discusses experimental and numerical seismic analyses of typical connections and wall systems used in cross-laminated (X-Lam) timber buildings. An extended experimental programme on typical X-Lam connections was performed at IVALSA Trees and Timber Institute. In addition, cyclic tests were also carried out on full-scale single and coupled X-Lam wall panels with different configurations and mechanical connectors subjected to lateral force. An advanced non-linear hysteretic spring to describe accurately the cyclic behaviour of connections was implemented in ABAQUS finite element software package as an external subroutine. The FE model with the springs calibrated on single connection tests was then used to reproduce numerically the behaviour of X-Lam wall panels, and the results were compared with the outcomes of experimental full-scale tests carried out at IVALSA. The developed model is suitable for evaluating dissipated energy and seismic vulnerability of X-Lam structures.
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Fire Resistance of Laminated Veneer Lumber (LVL) and Cross-Laminated Timber (XLAM) Elements

https://research.thinkwood.com/en/permalink/catalogue97
Year of Publication
2012
Topic
Fire
Material
CLT (Cross-Laminated Timber)
LVL (Laminated Veneer Lumber)
Author
Menis, Agnese
Organization
University of Cagliari
Year of Publication
2012
Format
Thesis
Material
CLT (Cross-Laminated Timber)
LVL (Laminated Veneer Lumber)
Topic
Fire
Keywords
Numerical models
Finite element (FE) model
Abaqus
Testing
Research Status
Complete
Summary
This research investigates the fire behaviour of laminated veneer lumber elements and cross-laminated timber panels. The study focused on some research questions regarding the fire resistance of unprotected and protected timber structural elements, the possibility to predict accurately the fire behaviour of timber elements through numerical modelling, and the accuracy of analytical estimations of fire resistance using simplified design methods. Experimental tests of small and large specimens exposed to fire on one or more sides and subjected to different types and levels of load were performed. The results highlight the good performance of timber structural elements in fire conditions. The collected data were used to validate two- and three-dimensional models implemented in the general purpose finite element code Abaqus. Thermal and mechanical analyses were carried out to estimate the temperature distribution within unprotected and protected cross-sections of different sizes, the fire resistance and the displacement of timber elements loaded in-plane and out-of-plane. Further, parametric studies assuming different timber properties-temperature relationships were also performed. The proposed numerical modelling can be used to investigate the fire behaviour of timber members made of other wood-based products and subjected to different loads and fire conditions. Experimental and numerical results were compared with analytical predictions obtained by using simplified design methods proposed by current codes of practice and recent research proposals. Numerical and analytical methods provide overall acceptable estimations of fire behaviour of timber members, especially considering the high variability that characterizes the wood material and the experimental tests, in particular the fire tests.
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Modelling the Fire Performance of Structural Timber Floors

https://research.thinkwood.com/en/permalink/catalogue212
Year of Publication
2012
Topic
Design and Systems
Fire
Material
Timber-Concrete Composite
Application
Floors
Author
O'Neill, James
Abu, Anthony
Carradine, David
Moss, Peter
Buchanan, Andrew
Year of Publication
2012
Format
Conference Paper
Material
Timber-Concrete Composite
Application
Floors
Topic
Design and Systems
Fire
Keywords
Failure Mechanisms
Finite Element Model
Fire Resistance
Thermo-mechanical
Full Scale
Conference
International Conference on Structures in Fire
Research Status
Complete
Notes
June 6-8, 2012, Zurich, Switzerland
Summary
This paper describes numerical modelling to predict the fire resistance of engineered timber floor systems. The floor systems under investigation are timber composite floors (various timber joist and box floor cross sections), and timber-concrete composite floors. The paper describes 3D numerical modelling of the floor systems using finite element software, carried out as a sequential thermo-mechanical analysis. Experimental testing of these floor assemblies is also being undertaken to calibrate and validate the models, with a number of full scale tests to determine the failure mechanisms for each floor type and assess fire damage to the respective system components. The final outcome of this research will be simplified design methods for calculating the fire resistance of a wide range of engineered timber floor systems.
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Design and Behavior of a Mid-Rise Cross-Laminated Timber Building

https://research.thinkwood.com/en/permalink/catalogue242
Year of Publication
2012
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Lenon, Conor
Organization
Colorado School of Mines
Year of Publication
2012
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Seismic
Keywords
Finite Element Model
Shake Table Test
Full Scale
Moment Resistance
Research Status
Complete
Summary
Cross-Laminated Timber (CLT) is a new engineered wood material that was introduced in the past decade as a promising candidate to build structures over 10 stories. So far, a handful of tall CLT buildings have been built in low seismic regions around the world. Full-scaled seismic shaking table tests revealed the vulnerability of this building type when resisting seismically-induced overturning. This study proposes a new analysis and design approach for developing overturning resistance for platform CLT buildings. New structural detailing is proposed to alter the moment-resisting mechanism and enable coupled action through the floor system. The method is applied to the design of a 12-story CLT building, which was evaluated numerically to assess the conservativeness of the design through system level finite element model simulations.
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Numerical Models for Dynamic Properties of a 14 Storey Timber Building

https://research.thinkwood.com/en/permalink/catalogue274
Year of Publication
2012
Topic
Design and Systems
Connections
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Utne, Ingunn
Organization
Norwegian University of Science and Technology
Year of Publication
2012
Format
Thesis
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Connections
Keywords
Dynamic Properties
Finite Element Model
Research Status
Complete
Summary
The world tallest timber building with height of 45 meters, is planned for Bergen, Norway. In this master thesis the dynamic properties of the case building, as proposed by Sweco and Artec, are investigated. The proposed structural concept with a glulam frame and power-storeys, have never previously been built, and it is desirable to develop and understanding of the dynamic problems concerning this building. Previous work have shown problems with acceleration levels for tall timber building, mostly due to the material properties of timber. Timber has high flexibility and strength combined with low weight. The main aim of the work have been to build a 3D-model of the case building in a finite element program, where numerical methods can be used to find the dynamic properties of the building. The wind load and acceleration levels are investigated, and found to be reasonable compared to various criterions presented. The effect of the stiffness in the connections, as well as the use of apartment modules are investigated. In addition a dynamic analysis is run, and stochastic subspace state space system identification is used to verify the model. This can later be used for verification of the actual building when finished, and will be an important method to determine the actual damping and stiffness. Based on the findings in this work, the concept is assumed feasible, possible with some changes an even better concept is achieved. It will be exciting to see how Sweco will develop the concept further in the next planning phase.
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Fire Safety Engineering of High Rise Timber Buildings

https://research.thinkwood.com/en/permalink/catalogue308
Year of Publication
2012
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Longhi, Giulio
Organization
Delft University of Technology
Year of Publication
2012
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Fire
Keywords
High-Rise
Code
Finite Element Model
Research Status
Complete
Summary
During this MSc thesis it has been carried out an extensive literature review on fire safety engineering, on timber behaviour on fire and on fire safety regulations in different countries. A preliminary design for a high rise cross laminated timber building (CLT) has been carried out in order to obtain a minimum thickness of the structural elements needed for the load bearing structure. This thickness has been verified according to prescriptive fire regulations. Furthermore, fire safety analyses have been performed to evaluate a more realistic fire behaviour of exposed timber structures. The finite element program SAFIR and the fire model OZone have been used in the advance calculations. Finally, it is shown that timber buildings should be designed according to advance fire safety approach and suggestions are given for developing a timber fire model.
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Non-Destructive Tests of Modulus of Elasticity for the Glued Laminated Timber Beams

https://research.thinkwood.com/en/permalink/catalogue323
Year of Publication
2012
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Melzerová, Lenka
Kuklík, Petr
Publisher
ScienceDirect
Year of Publication
2012
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Modulus of Elasticity
Non-Destructive Tests
Finite Element Model
Research Status
Complete
Series
Procedia Engineering
Summary
Twenty real dimensions beams from the glued laminated timber were tested in our previously works. Twenty advanced FE models were created precisely according to tested beams. Input files for FE models are lengths of segments and local moduli of elasticity. The segment is part of lamella between two finger joints. Each local modulus of elasticity was obtained via non-destructive penetration test. The output for comparison between real beam and FE model is displacement in half span. The quality of input data file from experiments is very important for the good agreement between real tested beams and FE models. In advanced FE models is described distribution of local moduli of elasticity via distribution function. The solution is based on the LHS. Accuracy of each distribution function is dependent on the number of measured local moduli of elasticity. In presented work was used probabilistic approach for determination of corresponding number of penetration tests as function of segments lengths. Results of this analysis will be used in the latter series of bending tests of new real dimensions beams and corresponding advanced FE models.
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171 records – page 1 of 18.