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7 records – page 1 of 1.

Bending Properties of Innovative Multi-Layer Composite Laminated Panels

https://research.thinkwood.com/en/permalink/catalogue1985
Year of Publication
2018
Topic
Mechanical Properties
Material
LSL (Laminated Strand Lumber)
OSL (Oriented Strand Lumber)
Application
Beams
Author
Zhou, Jianhui
Niederwestberg, Jan
Chui, Ying Hei
Gong, Meng
Year of Publication
2018
Format
Conference Paper
Material
LSL (Laminated Strand Lumber)
OSL (Oriented Strand Lumber)
Application
Beams
Topic
Mechanical Properties
Keywords
Bending Stiffness
Shear Stiffness
Moment Capacity
Failure Modes
Three Point Bending Test
Modal Test
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
An innovative multi-layer (3 and 5) composite laminated panel (CLP) with various layups were developed using sawn lumber and structural composite lumber (SCL) to address the rolling shear and gap issues of cross laminated timber (CLT). The bending properties including apparent and effective bending stiffness, shear stiffness, moment capacities and failure modes of CLPs were evaluated by a combination of modal tests and third-point bending tests of beam specimens cut from the panels. The static bending test results showed that the apparent bending stiffness values of 3-layer and 5-layer CLPs were up to 20% and 43% higher than the corresponding values of 3-layer and 5-layer generic CLT, respectively. The bending moment capacity values of 3-layer and 5-layer CLPs were up to 37% and 87% higher than the corresponding values of 3-layer and 5-layer generic CLT, respectively. The use of SCL in transverse layers eliminated the potential rolling shear failure in CLT and increased the stiffness properties. The apparent and effective bending stiffness predicted by shear analogy method had a good agreement with corresponding values measured by bending tests and/or modal tests. The prediction of bending moment capacity using shear analogy method cannot be validated due to the rolling shear failure and tension failure modes observed in certain groups.
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Characterizing Influence of Laminate Characteristics on Elastic Properties of Cross Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue221
Year of Publication
2014
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Niederwestberg, Jan
Chui, Ying Hei
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Modal Testing
Laminates
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Properties of CLT panels are influenced by the properties of their layers and the layer properties are in turn influenced by the structural characteristics of the laminate material. In order to realize the mechanical property potential of CLT panels it is necessary to understand the effects of laminate properties on the performance of the final product. This paper presents the approach and outcomes of an on-going study dealing with the evaluation of material and structural characteristics of laminates and their effects on overall characteristics of CLT using modal testing. Characteristics of “homogenised” layers and CLT panels were evaluated using modal and static testing. The suitability of test methods was established for single-layer panels and CLT panels. Relationships between overall single-layer properties and laminate characteristics were established. Differences in CLT properties calculated by different calculation models were discussed.
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Efficient Measurement of Elastic Constants of Cross Laminated Timber using Modal Testing

https://research.thinkwood.com/en/permalink/catalogue117
Year of Publication
2014
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Author
Zhou, Jianhui
Chui, Ying Hei
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Acoustics and Vibration
Keywords
Elasticity
Modal Testing
Modulus of Elasticity
Natural Frequency
Testing
Vibrations
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
It has been shown that measurement of elastic constants of orthotropic wood-based panel products can be more efficiently measured by modal testing technique. Identification of vibration modes and corresponding natural frequencies is key to the application of modal testing technique. This process is generally tedious and requires a number of measurement locations for mode shape identification. In this study, a simplified method for frequency identification was developed which will facilitate the adoption of the vibration-based testing technique for laboratory and industrial application. In the method, the relationship between frequency order and mode order is first studied considering the boundary condition, elastic properties of the orthotropic panel. An algorithm is proposed to predict the frequency values and mode indices based on corresponding normalized sensitivity to elastic constants, initial estimates of orthotropic ratios and measured fundamental natural frequency. The output from the algorithm can be used for identification of sensitive natural frequencies from up to three frequency spectra. Then the algorithm is integrated with the elastic calculation algorithm to extract the elastic constants from the sensitive frequencies. The elastic constants of cross laminated timber panels were measured by the proposed method. The moduli of elasticity agree well with static testing results. The calculated in-plane shear modulus was found to be within the expected range.
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Influence of Boundary Conditions in Modal Testing on Evaluated Elastic Properties of Mass Timber Panel

https://research.thinkwood.com/en/permalink/catalogue283
Year of Publication
2014
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Niederwestberg, Jan
Zhou, Jianhui
Chui, Ying Hei
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Mechanical Properties
Keywords
Modal Testing
Boundary Conditions
Elastic Properties
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Cross laminated timber (CLT) has the potential to play a major role in timber construction as floor and wall systems. In order to meet specific design needs and to make the use of CLT more effective, property evaluation of individual CLT panels is desirable. Static tests are time-consuming and therefore costly, and for massive products such as CLT practically impossible to implement. Modal testing offers a fast and more practical tool for the property evaluation of CLT and timber panels in general. This paper presents a comparison of different boundary conditions in modal testing in terms of accuracy, calculation effort and practicality. Single-layer timber panels as well as scaled CLT panels were fabricated. Three elastic properties of the panels were evaluated using modal testing methods with different boundary conditions (BCs). The results were compared with results from static test.
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Influence of Layer and Laminate Characteristics on Shear Properties of Cross Laminated Timber and Hybrids

https://research.thinkwood.com/en/permalink/catalogue1543
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
LSL (Laminated Strand Lumber)
OSL (Oriented Strand Lumber)
Application
Floors
Author
Niederwestberg, Jan
Chui, Ying Hei
Gong, Meng
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
LSL (Laminated Strand Lumber)
OSL (Oriented Strand Lumber)
Application
Floors
Topic
Mechanical Properties
Keywords
Shear Tests
Aspect Ratio
Growth Ring Orientation
Edge-Gluing
Static Test
Modal Test
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 1113-1122
Summary
In-plane shear and planar shear due to out-of-plane bending are important properties for the design of CLT-type floor systems. Properties of CLT-type panels are influenced by the orientation of the layer’s major stiffness directions and the properties of their layers. The layers are influenced by their characteristics, laminate aspect ratio, growth ring orientation and edge-gluing. In order to utilize the mechanical potential of CLT-type panels, it is necessary to understand the effects of layer and laminate properties on CLT performance. CLT and CLT-hybrid panels were tested in planar and in-plane shear tests. The shear properties were evaluated using static and modal test procedures, the accuracy of non-destructive test methods was evaluated. Relationships between specimen properties and the characteristics of laminates and layers, such as aspect ratio, growth ring orientation and edge-gluing, were established.
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Reduced and test-data correlated FE-models of a large timber truss with dowel-type connections aimed for dynamic analyses at serviceability level

https://research.thinkwood.com/en/permalink/catalogue3004
Year of Publication
2022
Topic
Mechanical Properties
Serviceability
Acoustics and Vibration
Material
Glulam (Glue-Laminated Timber)
Application
Trusses
Author
Landel, Pierre
Linderholt, Andreas
Organization
RISE Research Institutes of Sweden
Linnaeus University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Trusses
Topic
Mechanical Properties
Serviceability
Acoustics and Vibration
Keywords
Tall Timber Structures
Mechanical Connection
Dowel-type Fastener
Wind-induced Vibration
Modal Testing Properties
Connection Stiffness
FE-Model Reduction
Research Status
Complete
Series
Engineering Structures
Summary
The rise of wood buildings in the skylines of cities forces structural dynamic and timber experts to team up to solve one of the new civil-engineering challenges, namely comfort at the higher levels, in light weight buildings, with respect to wind-induced vibrations. Large laminated timber structures with mechanical joints are exposed to turbulent horizontal excitation with most of the wind energy blowing around the lowest resonance frequencies of 50 to 150 m tall buildings. Good knowledge of the spatial distribution of mass, stiffness and damping is needed to predict and mitigate the sway in lighter, flexible buildings. This paper presents vibration tests and reductions of a detailed FE-model of a truss with dowel-type connections leading to models that will be useful for structural engineers. The models also enable further investigations about the parameters of the slotted-in steel plates and dowels connections governing the dynamical response of timber trusses.
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Simultaneous measurement of elastic constants of engineered wood-based panels by modal testing

https://research.thinkwood.com/en/permalink/catalogue3124
Year of Publication
2018
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Zhou, J
Organization
University of New Brunswick
Year of Publication
2018
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Modal Testing
Elastic Properties
Effective Bending Stiffness
Effective Shear Stiffness
Research Status
Complete
Summary
With the advent of mass timber panels and the development of mid- to high-rise wood constructions, the renaissance of wood construction is underway from Europe to North America and throughout the world. Engineered wood-based panel products, especially mass timber panels, play an important role in the evolution of wood construction. Elastic properties are not only fundamental mechanical properties for structural design but also important indicators for quality control purposes. Accurate measurement of the global elastic properties of full-size panels is critical for their applications as load-bearing building components. An efficient and reliable non-destructive technique is required for the purposes both of characterizing elastic properties and of grading engineered wood-based panel products in the production line before processing for all kinds of structural applications. In this study, two vibrational non-destructive techniques employing modal testing for natural frequencies and other modal parameters were developed for simultaneous measurement of elastic constants of engineered wood-based panels. Both vibrational methods adopted modal testing of a rectangular plate with the boundary condition of a pair of opposite edges in the width direction simply supported and the other pair free. Compared with the elastic constant values by conventional static tests, both vibrational methods generally showed close agreement. The first method was developed for measuring the moduli of elasticity in both major and minor strength directions and the in-plane shear modulus of a panel based on free transverse vibration of rectangular thin orthotropic plates. A simplified modal testing procedure together with frequency identification methodology based on sensitivity analysis and an iterative algorithm were proposed as the means of achieving an efficient and reliable measurement with three and/ or four sensitive natural frequencies from only three impacts. The method was first verified with standard static test values in laboratory for full-size cross laminated timber, oriented strand board and medium density fibreboard. Then, 55 full-size cross laminated timber panels with different characteristics and from three manufacturers were tested in factory environments. The results showed that non-edge bonding and gap size had a negative effect on both Ey and Gxy and led to a large variation compared with edge bonded panels as well as with their corresponding prediction models (i.e., k-method, gamma method and shear analogy method). The second vibrational method was developed for determination of effective bending and shear stiffness values based on Mindlin plate theory with an exact frequency solution and a genetic algorithm for the inverse problem. The results showed that the transverse shear moduli of cross laminated timber panels can be accurately determined with proper shear correction factors and were verified by planar shear test values. According to an in-depth comparative study, the first vibrational method shows great potential for future development of a standard testing method and on-line quality control over other existing vibrational methods in terms of setup implementation, frequency identification, accuracy and the calculation efforts required. The second vibrational method is suggested for engineered wood-based panels with small transverse shear moduli and/ or small length/ width to thickness ratio. Both methods are deemed to be applicable to all kinds of composite plates.
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7 records – page 1 of 1.