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Connection and Performance of Two-Way CLT Plates

https://research.thinkwood.com/en/permalink/catalogue1482
Year of Publication
2018
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Application
Floors
Roofs
Author
Zhang, Chao
Lee, George
Lam, Frank
Organization
University of British Columbia
Year of Publication
2018
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Floors
Roofs
Topic
Mechanical Properties
Connections
Keywords
Two-Way
Bending Test
Modulus of Elasticity
Self-Tapping Screws
Glued-In-Rod
Steel Connectors
Steel Plates
Research Status
Complete
Summary
The two-way action of Cross Laminated Timber (CLT) is often ignored in the design of CLT due to its complexity. But in some cases, for example, large span timber floor/roof, the benefit of taking the two-way action into account may be considerable since it is often deflection controlled in the design. Furthermore CLT panels are typically limited to widths of less than 3 m. therefore, for practical applications, engaging CLT panels in two-way action as a plate in bending would require connecting two panels in the width/minor direction to take out-of-plane loading. To address this technically difficult situation, an innovative connection was developed to join the CLT panels in the minor direction to form a large continuous two-way plate. The two-way action of CLT was also quantified. Static bending test was conducted on CLT panels in the major and minor directions to measure the Modulus of Elasticity (MOE). This provided a benchmark for the following connection test, and data for the future development of computer modeling. The average apparent MOE was 9.09 GPa in the major direction and 2.37 GPa in the minor direction. Several connection techniques were considered and tested, including self-tapping wood screws, glued in steel rods, and steel connectors. One connecting system was found to be effective. For the panel configuration considered, the system was consisted of steel plates, self-tapping wood screws, and 45° screw washers. Two steel plates were placed on the tension side with sixteen screws, and one steel plates was placed on the compression side with four screws. When the screws were driven into the wood, the screws were tightly locked with the washers and steel plates, and at the same time, the wood members were pulled together by the screws. This eliminated any original gap within the connection. The connector was installed to join two CLT members in the minor direction. They were tested under bending with the same setup as above. The connected panels had an average apparent MOE of 2.37 GPa, and an average shear-free MOE of 2.44 GPa, both of which were higher than the counterpart in the full panels. The moment capacity of the connected panels was also high. The minimum moment capacity was 3.2 times the design value. Two large CLT panels were tested under concentrated loading with four corners simply supported. The deflection of nine locations within the panels was measured. This data will be used to validate the computer modeling for CLT two-way action.
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Development and Evaluation of CLT Shear Wall Using Drift Pinned Joint

https://research.thinkwood.com/en/permalink/catalogue673
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Nakashima, Shoichi
Kitamori, Akihisa
Komatsu, Kohei
Que, Zeli
Isoda, Hiroshi
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Connections
Mechanical Properties
Keywords
Cedar
Shear Failure
Drift Pin Joint
Steel Connectors
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
The connectors for the CLT shear wall with drift pin joint were suggested. The wall composed of five layers Japanese cedar CLT, steel connectors and drift pins (diameter d = 16mm). The horizontal shear performances of the walls were evaluated by static experiment and 2D frame analysis. The experimental parameter was number and position of drift pins. Characteristic failure was shear failure on the border of the laminae. There were good agreement on initial stiffness, yield load and second stiffness between experiment and calculation.
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Development of CLT Shear Frame Using Metal Plate Insert Connections

https://research.thinkwood.com/en/permalink/catalogue697
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Kitamori, Akihisa
Nakashima, Shoichi
Isoda, Hiroshi
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Connections
Mechanical Properties
Keywords
Failure Mode
Joints
Steel Plate
Strength
Steel Connectors
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
The purpose of this study is to develop a high strength leg joint for shear wall made of small size cross laminated timber panel in a simple system. The joint of CLT in which steel plate was inserted in the central slit and fixed by high strength bolt at inside of short steel pipes was proposed. In order to grasp the failure mode and strength of CLT member, material tests on embedment and shear were carried out using small CLT blocks. The test results indicated that there is few reinforce effect by cross bonding of each lamina. It was concluded that the precise estimation of the strength of CLT member is important in order to develop the joint proposed in this paper.
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Experimental Behavior of a Continuous Metal Connector for a Wood-Concrete Composite System

https://research.thinkwood.com/en/permalink/catalogue730
Year of Publication
2004
Topic
Connections
Design and Systems
Mechanical Properties
Material
Timber-Concrete Composite
PSL (Parallel Strand Lumber)
Application
Floors
Author
Clouston, Peggi
Civjan, Scott
Bathon, Leander
Publisher
Forest Products Society
Year of Publication
2004
Format
Journal Article
Material
Timber-Concrete Composite
PSL (Parallel Strand Lumber)
Application
Floors
Topic
Connections
Design and Systems
Mechanical Properties
Keywords
Pine
US
Continuous Steel Mesh
Steel Connectors
Push-Out Tests
Shear Strength
Stiffness
Bending Tests
Research Status
Complete
Series
Forest Products Journal
Summary
The benefits of using shear connectors to join wood beams to a concrete slab in a composite floor or deck system are many. Studies throughout the world have demonstrated significantly improved strength, stiffness, and ductility properties from such connection systems as well as citing practical building advantages such as durability, sound insulation, and fire resistance. In this study, one relatively new shear connector system that originated in Germany has been experimentally investigated for use with U.S. manufactured products. The connector system consists of a continuous steel mesh of which one half is glued into a southern pine Parallam® Parallel Strand Lumber beam and the other half embedded into a concrete slab to provide minimal interlayer slip. A variety of commercial epoxies were tested for shear strength and stiffness in standard shear or “push out” tests. The various epoxies resulted in a variety of shear constitutive behaviors; however, for two glue types,shear failure occurred in the steel connector resulting in relatively high initial stiffness and ductility as well as good repeatability. Slip moduli and ultimate strength values are presented and discussed. Full-scale bending tests, using the best performing adhesive as determined from the shear tests, were also conducted. Results indicate consistent, near-full composite action system behavior.
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Lateral-Load Resistance of Cross-Laminated Timber Shear Walls

https://research.thinkwood.com/en/permalink/catalogue1238
Year of Publication
2017
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Reynolds, Thomas
Foster, Robert
Bregulla, Julie
Chang, Wen-Shao
Harris, Richard
Ramage, Michael
Publisher
American Society of Civil Engineers
Year of Publication
2017
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Connections
Mechanical Properties
Keywords
Vertical Load
Lateral Load
Pullout Tests
Steel Connectors
Offset-Yield Criterion
Research Status
Complete
Series
Journal of Structural Engineering
Summary
Cross-laminated timber shear wall systems are used as a lateral load resisting system in multistory timber buildings. Walls at each level typically bear directly on the floor panels below and are connected by nailed steel brackets. Design guidance for lateral load resistance of such systems is not well established and design approaches vary among practitioners. Two cross-laminated two-story timber shear wall systems are tested under vertical and lateral load, along with pull-out tests on individual steel connectors. Comprehensive kinematic behavior is obtained from a combination of discrete transducers and continuous field displacements along the base of the walls, obtained by digital image correlation, giving a measure of the length of wall in contact with the floor below. Existing design approaches are evaluated. A new offset-yield criterion based on acceptable permanent deformations is proposed. A lower bound plastic distribution of stresses, reflecting yielding of all connectors in tension and cross-grain crushing of the floor panel, is found to most accurately reflect the observed behavior.
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