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Bamboo/Wood Composites and Structures Shear and Normal Strain Distributions in Multilayer Composite Laminated Panels under Out-of-Plane Bending

https://research.thinkwood.com/en/permalink/catalogue2769
Year of Publication
2021
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Niederwestberg, Jan
Zhou, Jianhui
Chui, Ying Hei
Huang, Dongsheng
Publisher
Hindawi Publishing Corporation
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Three Point Bending Test
Shear Test
Digital Image Correlation
Strain
Shear Analogy
Finite Element Modelling
Stress
Research Status
Complete
Series
Advances in Civil Engineering
Summary
Innovative mass timber panels, known as composite laminated panels (CLP), have been developed using lumber and laminated strand lumber (LSL) laminates. In this study, strain distributions of various 5-layer CLP and cross-laminated timber (CLT) were investigated by experimental and two modelling methods. Seven (7) different panel types were tested in third-point bending and short-span shear tests. During the tests, the digital imaging correlation (DIC) technique was used to measure the normal and shear strain in areas of interest. Evaluated component properties were used to determine strain distributions based on the shear analogy method and finite element (FE) modelling. The calculated theoretical strain distributions were compared with the DIC test results to evaluate the validity of strain distributions predicted by the analytical model (shear analogy) and numerical model (FE analysis). In addition, the influence of the test setup on the shear strain distribution was investigated. Results showed that the DIC strain distributions agreed well with the ones calculated by the shear analogy method and FE analysis. Both theoretical methods agree well with the test results in terms of strain distribution shape and magnitude. While the shear analogy method shows limitations when it comes to local strain close to the supports or gaps, the FE analysis reflects these strain shifts well. The findings support that the shear analogy is generally applicable for the stress and strain determination of CLP and CLT for structural design, while an FE analysis can be beneficial when it comes to the evaluation of localized stresses and strains. Due to the influence of compression at a support, the shear strain distribution near the support location is not symmetric. This is confirmed by the FE method.
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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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Comparison of Theoretical and Laboratory Out-of-Plane Shear Stiffness Values of Cross Laminated Timber Panels

https://research.thinkwood.com/en/permalink/catalogue2177
Year of Publication
2018
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Niederwestberg, Jan
Zhou, Jianhui
Chui, Ying-hei
Organization
University of Alberta
University of Northern British Columbia
Publisher
MDPI
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Shear Behaviour
Out Of Plane
Shear Stiffness
Timoshenko Theory of Bending
Shear Modulus
Research Status
Complete
Series
Buildings
Summary
The lay-up of cross laminated timber (CLT) leads to significant differences in properties over its cross-section. Particularly the out-of-plane shear behavior of CLT is affected by the changes in shear moduli over the cross-section. Results from laboratory shear tests are used to evaluate the shear stiffness of 3- and 5-layer CLT panels in their major and minor strength direction. The results are compared to calculated shear stiffness values on evaluated single-layer properties as well as commonly used property ratios using the Timoshenko beam theory and the shear analogy method. Differences between the two calculation approaches are pointed out. The shear stiffness is highly sensitive to the ratio of the shear modulus parallel to the grain to the shear modulus perpendicular to the grain. The stiffness values determined from two test measurements are compared with the calculated results. The level of agreement is dependent on the number of layers in CLT and the property axis of the CLT panels.
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Cross-Laminated Timber Shear Walls in Balloon Construction: Seismic Performance of Steel Connections

https://research.thinkwood.com/en/permalink/catalogue2413
Year of Publication
2019
Topic
Seismic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Walls

Development of Rotational Fixity Factors for Vibration Design of Cross-Laminated Timber Floors

https://research.thinkwood.com/en/permalink/catalogue2843
Year of Publication
2018
Topic
Acoustics and Vibration
Serviceability
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Zhang, Sigong
Zhou, Jianhui
Niederwestberg, Jan
Chui, Ying Hei
Organization
University of Alberta
University of Northern British Columbia
Publisher
Preprints
Year of Publication
2018
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Serviceability
Keywords
End Support
Vibration Serviceability
Floor-Wall Connection
Research Status
Complete
Summary
As an emerging building solution, cross-laminated timber (CLT) floors have been increasingly used in mass timber construction. The current vibration design of CLT floors is conservative due to the assumption of simple support conditions in the floor-to-wall connections. It is noted that end fixity occurs as a result of clamping action at the ends, arising from the gravity load applied by the structure above the floor and by the mechanical fasteners. In this paper, the semi-rigid floor-to-wall connections are treated as elastically restrained edges against rotations to account for the effect of partial constraint. A rotational end-fixity factor was first defined to reflect the relative bending stiffness between CLT floors and elastic restraints at the edges. Then, for the design of vibration serviceability of CLT floors as per the Canadian Standard for Engineering Design in Wood (CSA O86), restraint coefficients were defined and their analytical expressions were derived for natural frequencies and the mid-span deflection under a concentrated load, respectively. In particular, a simplified formula of the restraint coefficient for the fundamental frequency was developed to assist engineers in practical design. At last, by comparing with reported experimental data, the proposed design formula showed excellent agreement with test results. In the end, the proposed end fixity factor with their corresponding restraint coefficients is recommended as an effective mechanics-based approach to account for the effect of end support conditions of CLT floors.
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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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Mechanical Properties of Innovative, Multi-Layer Composite Laminated Panels

https://research.thinkwood.com/en/permalink/catalogue2178
Year of Publication
2018
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
LSL (Laminated Strand Lumber)
Author
Niederwestberg, Jan
Zhou, Jianhui
Chui, Ying-hei
Organization
University of Alberta
University of Northern British Columbia
Publisher
MDPI
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
LSL (Laminated Strand Lumber)
Topic
Mechanical Properties
Keywords
Rolling Shear Failure
Shear Resistance
Bending Stiffness
Moment Stiffness
Research Status
Complete
Series
Buildings
Summary
Cross-laminated timber (CLT) possesses both good shape stability and possible two-way force transfer ability due to its crosswise lamination. However, the transverse layers in CLT are prone to rolling shear failure under an out-of-plane load. An innovative multi-layer composite laminated panel (CLP) was developed by combining structural composite lumber (SCL) and dimension lumber to overcome the rolling shear failure while maintaining the high mechanical performance and aesthetic appearance of natural wood. The mechanical properties of 5-layer CLP that consisted of laminated strand lumber (LSL) and dimension lumber with different layups were evaluated by both static and modal tests. The results showed that the shear resistance, bending stiffness, and moment resistance of CLP were up to 143%, 43%, and 87% higher than their counterparts of regular CLT, respectively. The failure modes observed in both shear and bending tests indicated that the use of LSL in transverse layers could eliminate the potential rolling shear failure in CLT. With the lamination properties from components tests as inputs, the validity of shear analogy method was assessed by test results. The mechanical properties can be well predicted by shear analogy method except for the bending moment resistance of CLP and CLT with either rolling failure in the cross layer or tension failure in the bottom layer.
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Seismic Design Approach for MTP Balloon Construction - Connection Properties

https://research.thinkwood.com/en/permalink/catalogue2648
Topic
Mechanical Properties
Connections
Author
Niederwestberg, Jan
Organization
University of Alberta
Topic
Mechanical Properties
Connections
Keywords
Strength
Stiffness
Ductility
Energy Dissipation
Failure Mode
Steel Plates
Monotonic Loading Tests
Cyclic Loading Tests
Research Status
In Progress
Summary
The objective of this research is to characterize of load-deformation responses of tested connections(stiffness, strength, ductility, energy dissipation, failure modes) by testing large STS connections with steel side plates under monotonic and cyclic loads.
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10 records – page 1 of 1.