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Development of Modular System in Midrise to Tall Wood Buildings Phase II

https://research.thinkwood.com/en/permalink/catalogue2530
Year of Publication
2020
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Zhang, Chao
Organization
Timber Engineering and Applied Mechanics (TEAM) Laboratory
Year of Publication
2020
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Topic
Design and Systems
Keywords
Openings
Lateral Performance
Shear Walls
SPF
Spruce-Pine-Fir
Loading Tests
Language
English
Research Status
Complete
Summary
This project studied the effect of openings on the lateral performance of CLT shear walls and the system behavior of the walls in a module. Three-layer Cross Laminated Timber (CLT) was used for manufacturing the wall and module specimens. The laminar was Spruce-Pine-Fir (SPF) #2&Better for both the major and minor layers. Each layer was 35 mm thick. The panel size was 2.44 m × 2.44 m. Four configurations of walls were investigated: no opening, 25% opening, 37.5% opening, and 50% opening. The opening was at the center of the wall and in the shape of a square. A CLT module was made from two walls with 50% openings, with an overall thickness of 660 mm. The specimens were tested under monotonic loading and reverse-cyclic loading, in accordance with ASTM E564-06 (2018) and ASTM E2126-19. The wall without opening had an average peak load of 111.8 kN. It had little internal deformation and the failure occurred at the connections. With a 25% opening, deformation within the wall was observed but the failure remained at the connections. It had the same peak load as the full wall. When the opening was increased to 37.5%, the peak load decreased by 6% to 104.9 kN and the specimens failed in wood at the corners of the opening. Further increasing the opening to 50%, the peak load dropped drastically to 63.4 kN, only 57% of the full wall. The load-displacement relationship was approximately linear until the load reached 60% of the peak or more. Compared to the full wall, the wall with 25% opening had 65% of the stiffness. When the opening increased to 37.5% and 50%, the stiffness reduced to 50% and 24% of the full wall, respectively. The relationship between stiffness and opening ratio was approximately linear. The loading protocol had effect on the peak load but not on the stiffness. There was more degradation for larger openings under reverse-cyclic loading. The performance of the module indicated the presence of system effect that improves the ductility of the wall, which is important for the seismic performance of the proposed midrise to tall wood buildings. The test data was compared to previous models found in literature. Simplified analytical models were also developed to estimate the lateral stiffness and strength of CLT wall with openings.
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Force Transfer Around Openings in CLT Shear Walls

https://research.thinkwood.com/en/permalink/catalogue256
Year of Publication
2014
Topic
Seismic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Pai, Sai
Organization
University of British Columbia
Year of Publication
2014
Country of Publication
Canada
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Mechanical Properties
Keywords
Openings
Transfer Forces
Strength
Stiffness
Language
English
Research Status
Complete
Summary
During an earthquake, shear walls can experience damage around corners of doors and windows due to development of stress concentration. Reinforcements provided to minimize this damage are designed for forces that develop at these corners known as transfer forces. In this thesis, the focus is on understanding the forces that develop around opening corners in cross laminated timber (CLT) shear walls and reinforcement requirements for the same. In the literature, four different analytical models are commonly considered to determine the transfer force for design of wood-frame shear walls. These models have been reviewed in this thesis. The Diekmann model is found to be the most suitable analytical model to determine the transfer force around a window-type opening. Numerical models are developed in ANSYS to analyse the forces around opening corners in CLT shear walls. CLT shear walls with cut-out openings are analysed using a threedimensional brick element model and a frame model. These models highlight the increase in shear and torsion around opening corners due to stress concentration. The coupled-panel construction practice for CLT shear walls with openings is analysed using a continuum model calibrated to experimental data. The analysis shows the increase in strength and stiffness of walls, when tie-rods are used as reinforcement. Analysis results also indicate that the tie-rods should be designed to behave linearly for optimum performance of the wall. Finally, a linear regression model is developed to determine the stiffness of a simply-supported CLT shear wall with a window-type opening. This model provides insight into the effect of various geometrical and material parameters on the stiffness of the wall. The process of model development has been explained, which can be improved further to include the behaviour of anchors.
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Glulam Beams with Holes

https://research.thinkwood.com/en/permalink/catalogue211
Year of Publication
2014
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Jelec, Mario
Varevac, Damir
Zovkic, Jurko
Organization
University of Osijek
Year of Publication
2014
Country of Publication
Croatia
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Finite Element Model
Openings
Numerical model
Stress Distribution
Language
English
Research Status
Complete
Series
e-GFOS
Summary
This paper provides a systematic review of research on glued laminated timber beams with circular and rectangular openings. Experiments on girders with unreinforced openings varied several parameters, including the girder span and shape, opening position and shape, and the relationship between the stress state near the opening and the ratio of opening size to girder size. We compare experimental results with recommendations given by DIN 1052:2004-08, DIN EN 1995-1-1/NA: 2010, prEN 1995-1-1: Final Draft, analytical expressions, and other relevant standards, as well as with the results of numerical models using the finite element method. Because of its myriad complexities and uncertainties, this area remains open for further research and for implementation of that research into practical design guidelines and rules.
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Influence of Openings on the Shear Strength and Stiffness of Cross Laminated Timber (CLT) Panels

https://research.thinkwood.com/en/permalink/catalogue2710
Year of Publication
2020
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Walls
Shear Walls
Author
Aljuhmani, Ahmad
Ogasawawra, A.
Atsuzawa, E.
Alwashali, Hamood
Shegay, A. V.
Tafheem, Zasiah
Maeda, Masaki
Year of Publication
2020
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Walls
Shear Walls
Topic
Mechanical Properties
Keywords
Diagonal Compression Test
Openings
Lateral Strength
In-Plane Shear Stiffness
Panels
Language
English
Conference
World Conference on Earthquake Engineering
Research Status
Complete
Summary
In the last decade, cross laminated timber (CLT) has been receiving increasing attention as a promising construction material for multi-storey structures in areas of high seismicity. In Japan, application of CLT in building construction is still relatively new; however, there is increasing interest in CLT from researchers as well as construction companies. Furthermore, the Japanese government is providing construction cost subsidies for new CLT structures as it is a carbon neutral and sustainable material. The high shear and compressive strength of CLT makes it a good candidate for use as shear walls in mid-rise buildings. One important aspect of CLT walls, and one that is presently poorly understood, is the influence of openings on the shear carrying capacity. Openings are often necessary in CLT panels either in form of windows, doors, lift shaft openings or installation of building services. Concerning this aspect, the code regulations in Japan are relatively strict, such that if openings exceeded certain prescribed limits, the entire CLT panel is considered as a non-structural element, and its contribution to lateral strength is totally ignored. Furthermore, as the maximum opening size is usually governed by edge distance constraints, the size of openings that designers can use is inevitably limited by the standard sizes supplied by the manufacturers. As a result, designers are obligated to adopt very small opening size. This is thought to be a very conservative approach. The main purpose of this paper is to experimentally evaluate the influence of openings on seismic capacity; strength and stiffness reduction, as well as failure mode with changing opening size and opening aspect ratio. In addition, check the validity of the Japanese code regulations with regards to openings in CLT panels. In this study, six 5-layer CLT panels containing different openings were tested. The parameters considered include the size and layout of the opening. The panels were specifically designed with openings that would render them ineffective in resisting lateral loads according to the Japanese standard. However, in addition to the six panels, one panel without openings and one panel with openings that meet the Japanese standard was designed. All the CLT panels were tested in uniaxial diagonal compression in order to simulate pure shear loading. The CLT panels and the loading setup were designed such that the resulting failure mode will be governed by a shear mechanism. The main focus of the experiment was to relate the deterioration of the lateral strength and stiffness of the panels to the size and layout of the opening. The results showed that the panels with openings with the same area have relatively different failure direction and reduction factors for panel shear strength and stiffness, and that is due to the shear weak and strong direction that CLT panels have. Also, the effect of openings on the reduction of stiffness for CLT panels was found to be greater than their effect on the reduction of shear strength. The prescribed equation in the Japanese CLT Guidebook underpredicts stiffness reduction, and has discrepancies with regard to strength as the difference of panel strengths in weak and strong directions are not considered.
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In-Plane Stiffness of CLT Panels With and Without Openings

https://research.thinkwood.com/en/permalink/catalogue1668
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Shahnewaz, Md
Tannert, Thomas
Alam, Shahria
Popovski, Marjan
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Mechanical Properties
Keywords
In-Plane Loading
Finite Element Analysis
Elastic Stiffness
Openings
Thickness
Aspect Ratios
Analytical Model
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 3813-3820
Summary
The research presented in this paper analysed the stiffness of Cross-Laminated-Timber (CLT) panels under in-plane loading. Finite element analysis (FEA) of CLT walls was conducted. The wood lamellas were modelled as an orthotropic elastic material, while the glue-line between lamellas were modelled using non-linear contact elements. The FEA was verified with test results of CLT panels under in-plane loading and proved sufficiently accurate in predicting the elastic stiffness of the CLT panels. A parametric study was performed to evaluate the change in stiffness of CLT walls with and without openings. The variables for the parametric study were the wall thickness, the aspect ratios of the walls, the size and shape of the openings, and the aspect ratios of the openings. Based on the results, an analytical model was proposed to calculate the in-plane stiffness of CLT walls with openings more accurately than previously available models from the literature.
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Performance of Cross-Laminated Timber Shear Walls for Platform Construction Under Lateral Loading

https://research.thinkwood.com/en/permalink/catalogue1268
Year of Publication
2018
Topic
Seismic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Shahnewaz, Md
Organization
University of British Columbia
Year of Publication
2018
Country of Publication
Canada
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Connections
Keywords
Lateral Loading
In-Plane Stiffness
Platform Buildings
Openings
Thickness
Aspect Ratios
Language
English
Research Status
Complete
Summary
Cross-laminated timber (CLT) is gaining popularity in residential and non-residential applications in the North American construction market. CLT is very effective in resisting lateral forces resulting from wind and seismic loads. This research investigated the in-plane performance of CLT shear wall for platform-type buildings under lateral loading. Analytical models were proposed to estimate the in-plane stiffness of CLT wall panels with openings based on experimental and numerical investigations. The models estimate the in-plane stiffness under consideration of panel thickness, aspect ratios, and size and location of the openings. A sensitivity analysis was conducted to reduce the number of model parameters to those that have a significant impact on the stiffness reduction of CLT wall panels with openings. Finite element models of CLT wall connections were developed and calibrated against experimental tests. The results were incorporated into models of CLT single and coupled shear walls. Finite element analyses were conducted on CLT shear walls and the results in terms of peak displacements, peak loads and energy dissipation were in good agreement when compared against full-scale shear wall tests. A parametric study on single and coupled CLT shear walls was conducted with variation of number and type of connectors. The seismic performance of 56-single and 40-coupled CLT shear walls’ assembles for platform-type construction were evaluated. Deflection formulas were proposed for both single and coupled CLT shear walls loaded laterally in-plane that in addition to the contributions of CLT panels and connections, also account for the influence of adjacent perpendicular walls and floors above and illustrated with examples. Analytical equations were proposed to calculate the resistance of CLT shear walls accounting for the kinematic behaviour of the walls observed in experimental investigations (sliding, rocking and combined sliding-rocking) and illustrated with examples. Different configurations (number and location of hold-downs) of single and coupled CLT walls were considered. The findings presented in this thesis will contribute to the scientific body of knowledge and furthermore will be a useful tool for practitioners for the successful seismic design of CLT platform buildings in-line with the current CSA O86 provisions.
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Structural Behaviour of Point-Supported CLT Floor Systems

https://research.thinkwood.com/en/permalink/catalogue1476
Year of Publication
2016
Topic
Mechanical Properties
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Popovski, Marjan
Chen, Zhiyong
Gafner, Bernhard
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Mechanical Properties
Acoustics and Vibration
Keywords
Brock Commons
Natural Frequency
Stiffness
Deformation
Load Carrying Capacity
Two-Way
Compression
Failure Mechanisms
Openings
Point-Supported
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria
Summary
This paper presents an experimental investigation of the structural behaviour and dynamic characteristics of an innovative, double-span, point-supported Cross Laminated Timber (CLT) floor system for an 18-stroey woodhybrid student residence building at the University of British Columbia Campus in Vancouver, Canada. Eighteen CLT floor specimens with or without service openings were fabricated by three manufacturers and tested. The fundamental natural frequency, stiffness and deformability, load-carrying capacity, two-way action, compression perpendicular to grain at the supports, and the failure mechanism of the floor systems were investigated. In addition, the effect of openings in the floors was investigated along with the manufacturer-related properties of the CLT floors were examined. The tests gave an insight into the structural behaviour of this innovative floor system, provided test data that was used for calibration of the Finite Element Models of the building, and helped choose the right product for the floors.
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7 records – page 1 of 1.