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Connection Wood Brittle Failure in Cross-Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue1552
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Zarnani, Pouyan
Quenneville, Pierre
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Fasteners
Brittle Failure
Failure Modes
Stiffness-Based Design Approach
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 1233-1240
Summary
The introduction of Cross-laminated Timber (CLT) as an engineered timber product has played a significant role in the considerable progress of timber construction in recent years. Extensive research has been conducted in Europe and more recently in Canada to evaluate the fastening capacity of different types of fasteners in CLT. While ductile capacities calculated using the yield limit equations are quite reliable for fastener resistance in connections, however, they do not take into account the possible brittle failure modes of the connection which could be the governing failure mode in multi-fastener joints. Therefore, a stiffness-based design approach which has already been developed by the authors and verified in LVL, glulam and lumber has been adapted to determine the block-tear out resistance of connections in CLT by considering the effect of perpendicular layers. The comparison between the test results on riveted connections conducted at the University of Auckland (UoA) and at the Karlsruhe Institute of Technology (KIT) and the predictions using the new model and the one developed for uniformly layered timber products show that the proposed model provides higher predictive accuracy and can be used as a design provision to control the brittle failure of wood in CLT connections.
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Ductile Cross Laminated Timber (CLT) Platform Structures with Passive Damping

https://research.thinkwood.com/en/permalink/catalogue1728
Year of Publication
2016
Topic
Seismic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Hashemi, Ashkan
Loo, Wei Yuen
Masoudnia, Reza
Zarnani, Pouyan
Quenneville, Pierre
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Seismic
Mechanical Properties
Keywords
Low-Rise
Numerical Model
Reverse Cyclic Loading
Quasi-Static
Simulation
Strength
Slip
Platform Buildings
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 4730-4737
Summary
Multi-storey platform cross laminated timber (CLT) structures are becoming progressively desirable for engineers and owners. This is because they offer many significant advantages such as speed of fabrication, ease of construction, and excellent strength to weight ratio. With platform construction, stories are fixed together in a way that each floor bears into load bearing walls, therewith creating a platform for the next level. The latest research findings have shown that CLT platform buildings constructed with traditional fasteners can experience a high level of damage especially in those cases where the walls have adopted hold-down brackets and shear connectors with nails, rivets or screws. Thus, the current construction method for platform CLT structures is less than ideal in terms of damage avoidance. The main objective of this study is to develop a low damage platform timber panelised structural system using a new configuration of slip friction devices in lieu of traditional connectors. A numerical model of such a system is developed for a low rise CLT building and then is subjected to reversed cyclic load simulations in order to investigate its seismic performance. The result of these quasi-static simulations demonstrated that the system maintained the strength through numerous cycles of loading and unloading. In addition to this, the system is capable of absorbing significant amount of energy. The findings of this study demonstrate the proposed concept has the potential to be developed as a low damage seismic solution for CLT platform buildings.
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Dynamic Evaluation of Hybrid Timber-Steel Moment-Frame Structure Using Resilient Slip Friction Connections

https://research.thinkwood.com/en/permalink/catalogue1756
Year of Publication
2016
Topic
Connections
Seismic
Mechanical Properties
Material
Steel-Timber Composite
Application
Frames
Author
Valadbeigi, Armin
Zarnani, Pouyan
Quenneville, Pierre
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
Steel-Timber Composite
Application
Frames
Topic
Connections
Seismic
Mechanical Properties
Keywords
Resilient Slip Friction Joint
Damping
Base Shear
Displacement
Acceleration
Self-Centering
Moment-Resisting
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 5031-5040
Summary
This study introduces a new resilient slip friction joint for framed hybrid structures. The proposed connection has a self-centring behaviour in addition to damping characteristic. This innovative Resilient Slip Friction (RSF) joint is replaced with the conventional beam to column connections. The RSF joint provides energy dissipation...
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Failure Modes in CLT Connections

https://research.thinkwood.com/en/permalink/catalogue495
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Mohammad, Mohammad
Quenneville, Pierre
Salenikovich, Alexander
Zarnani, Pouyan
Munoz, Williams
Year of Publication
2014
Country of Publication
Canada
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Failure Modes
Brittle Behaviour
Canada
New Zealand
Dowels
Bolts
Rivets
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Information on ductile and brittle failure modes is critical for proper design of timber connections in Crosslaminated Timber (CLT). While considerable research has been conducted in Europe and Canada on the ductile performance of connections in CLT, little is known about the brittle behaviour. This paper presents new information from testing programs and analysis performed in Canada and in New Zealand on the brittle performance of dowel-type fasteners in CLT. The testing programs have been designed to trigger brittle failure modes based on minimum end distances and fasteners spacings specified in the Canadian timber design standard. Timber rivets and bolts/dowels are covered under this study. At the time of writing of this abstract, the testing program is advancing and results will be available at the time of paper submission.
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Group Tear-Out in Small-Dowel-Type Timber Connections: Brittle and Mixed Failure Modes of Multinail Joints

https://research.thinkwood.com/en/permalink/catalogue579
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Author
Zarnani, Pouyan
Quenneville, Pierre
Publisher
American Society of Civil Engineers
Year of Publication
2014
Country of Publication
United States
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Topic
Connections
Mechanical Properties
Keywords
dowel-type connections
Load Carrying Capacity
Brittle Failure
Failure Modes
Language
English
Research Status
Complete
Series
Journal of Structural Engineering
Summary
In existing wood strength prediction models for parallel to grain failure in timber connections using dowel-type fasteners, different methods consider the minimum, maximum, or summation of the tensile and shear capacities of the failed wood block planes. It is postulated that these methods are not appropriate since the stiffness of the adjacent wood loading the tensile and shear planes differs, and this leads to uneven load distribution among the resisting planes. A closed-form analytical method to determine the load-carrying capacity of wood under parallel-to-grain loading in small-dowel-type connections in timber products is thus proposed. For the wood strength, the stiffness of the adjacent loading volumes and strength of the failure planes subjected to nonuniform shear and tension stresses are considered. The effective wood thickness for the brittle failure mode is derived and related to the elastic deformation of the fastener. A mixed failure mode is also defined (a mixture of brittle and ductile) and depends on the governing ductile failure mode of the fastener. To help the designer, an algorithm is presented that allows the designer to calculate the resistances associated with predictions of the different possible brittle, ductile, and mixed failure modes. The proposed stiffness-based model has already been verified in brittle and mixed failure modes of timber rivet connections. In the research reported in this paper, an extended application is proposed for other small-dowel-type fasteners such as nails and screws. Results of nailed joint tests on laminated veneer lumber (LVL) and the test data available from the literature on glulam confirm the validity of this new method, and show that it can be used as a design provision for wood load-carrying capacity prediction of small-dowel-type timber connections.
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New Design Approach for Controlling Brittle Failure Modes of Small-Dowel-Type Connections in Cross-Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue155
Year of Publication
2015
Topic
Connections
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Zarnani, Pouyan
Quenneville, Pierre
Publisher
ScienceDirect
Year of Publication
2015
Country of Publication
Netherlands
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Design and Systems
Keywords
Brittle Failure Mode
Fasteners
Stiffness
Language
English
Research Status
Complete
Series
Construction and Building Materials
Summary
The introduction of Cross-laminated Timber (CLT) as an engineered timber product has played a significant role in considerable progress of timber construction in recent years. Extensive research has been conducted in Europe and more recently in Canada to evaluate the fastening capacity of different types of fasteners in CLT. While ductile capacities calculated using the yield limit equations are quite reliable for fastener resistance in connections, however, they do not take into account the possible brittle failure mode of the connection which could be the governing failure mode in multi-fastener joints. Therefore, a stiffness-based design approach which has already been developed by the authors and verified in LVL, glulam and lumber has been adapted to determine the block-tear out resistance of connections in CLT by considering the effect of perpendicular layers. The comparison between the test results on riveted connections conducted at the University of Auckland (UoA) and the Karlsruhe Institute of Technology (KIT) and the predictions using the new model and the one developed for uniformly layered timber products show that the proposed model provides higher predictive accuracy and can be used as a design provision to control the brittle failure of wood in CLT connections.
Online Access
Free
Resource Link
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New Design Approach for Wood Brittle Failure Mechanisms in Timber Connections

https://research.thinkwood.com/en/permalink/catalogue317
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Author
Zarnani, Pouyan
Quenneville, Pierre
Year of Publication
2014
Country of Publication
New Zealand
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Topic
Connections
Mechanical Properties
Keywords
Joints
Fasteners
European Yield Model
New Zealand
Ductile
Brittle
Failure Mechanisms
Language
English
Conference
Australasian Structural Engineering Conference
Research Status
Complete
Notes
July 9-11, 2014, Auckland, New Zealand
Summary
Timber construction has experienced considerable progress in recent years. In such progress, apart from the implementation of new engineered timber products, the advancement of timber joints has played a significant role. The design procedures for timber connections in most design codes are based mainly on the yielding capacity of the fasteners using the European Yield Model (EYM). While the EYM theory provides accurate predictions for connections that fail in a ductile fashion, it does not take into account the failure of the connections due to the brittle rupture of wood as the consequence of fasteners group effect. Such a significant gap in the design of connections also applies to the New Zealand (NZS 3603) and Australian (AS 1720.1) timber design standards. A new design approach is presented which allows the practitioners to predict the connection capacity associated with different brittle wood failure mechanisms. An extensive testing regime has been conducted on high load-transfer capacity joints using timber rivets under longitudinal and transverse loadings on New Zealand Radiata Pine laminated veneer lumber (LVL) and glulam. The results verify the proposal and prove its reliability. A design guide was also developed which could eventually become a design clause in the next revision of the New Zealand timber design standard NZS 3603.
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Seismic Resilient Structures with Cross Laminated Timber (CLT) Walls Coupled with Innovative Resilient Slip Friction (RSF) Joints

https://research.thinkwood.com/en/permalink/catalogue1478
Year of Publication
2017
Topic
Design and Systems
Seismic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Hybrid Building Systems
Author
Hashemi, Ashkan
Quenneville, Pierre
Zarnani, Pouyan
Year of Publication
2017
Country of Publication
New Zealand
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Hybrid Building Systems
Topic
Design and Systems
Seismic
Mechanical Properties
Keywords
Timber-Steel Hybrid
Lateral Load Resisting System
Resilient Slip Friction Joint
Self-Centering
Energy Dissipation
Numerical Model
Language
English
Conference
New Zealand Society for Earthquake Engineering Conference
Research Status
Complete
Notes
April 27-29, 2017, Wellington, New Zealand
Summary
There is an increasing public pressure to have damage avoidant structural systems in order to minimize the destruction after severe earthquakes with no post-event maintenance. This study presents and investigates a hybrid steel-timber damage avoidant Lateral Load Resisting System (LLRS) using Cross Laminated Timber (CLT) walls coupled with innovative Resilient Slip Friction (RSF) joints and boundary steel columns. RSF joints are used as ductile links between the adjacent walls or between the walls and the columns. These joints are capable to provide a self-centring behaviour (the main deficiency of conventional friction joints) in addition to a high rate of energy dissipation all in one compact device. One significant advantage of this system is that there are practically no bending stresses in the CLT panels which considerably increases the allowable capacity of the system. A numerical model for a four story prototype building containing the proposed concept is developed and subjected to time-history simulations. The results confirm that this system can be considered as the new generation of resilient LLRSs for different types of structures.
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Seismic Resistant Cross Laminated Timber Structures Using an Innovative Resilient Friction Damping System

https://research.thinkwood.com/en/permalink/catalogue1479
Year of Publication
2017
Topic
Connections
Seismic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Hybrid Building Systems
Author
Hashemi, Ashkan
Valadbeigi, Armin
Masoudnia, Reza
Zarnani, Pouyan
Year of Publication
2017
Country of Publication
New Zealand
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Hybrid Building Systems
Topic
Connections
Seismic
Mechanical Properties
Keywords
Resilient Slip Friction Joint
Energy Dissipation
Self-Centering
Hold-Down
Language
English
Conference
New Zealand Society for Earthquake Engineering Conference
Research Status
Complete
Notes
April 27-29, 2017, Wellington, New Zealand
Summary
Multi-storey timber structures are becoming progressively desirable owing to their aesthetic and environmental benefits and to the high strength to weight ratio of timber. A recent trend in timber building industry is toward cross laminated timber (CLT) panelized structures. The shake table tests within the SOFIE project have shown that the CLT buildings constructed with traditional methods can experience high damage especially at the connections which generally consist of hold-down brackets and shear connectors with mechanical fasteners such as nails or bolts. Thus, current construction methods are not recognised as reliable in seismic prone areas. The main objective of this project is to develop a new low damage structural concept using innovative resilient slip friction (RSF) damping devices. The component test results demonstrate the capacity of this novel joint for dissipating earthquake energy as well as self-centring to minimize the damage and the residual drift after a severe event. The application of RSF joints as holddown connectors for walls were investigated through numerical studies. Moreover, a core wall system comprised of cross laminated timber and RSF connectors is subjected to time-history earthquake simulations. The numerical results exhibit no residual displacement alongside a significant reduction in peak acceleration which can be attributed to significant amount of dissipated seismic energy over the RSF joints within the system.
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Splitting Strength of Small Dowel-Type Timber Connections: Rivet Joint Loaded Perpendicular to Grain

https://research.thinkwood.com/en/permalink/catalogue580
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Author
Zarnani, Pouyan
Quenneville, Pierre
Publisher
American Society of Civil Engineers
Year of Publication
2014
Country of Publication
United States
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Topic
Connections
Mechanical Properties
Keywords
Timber Rivets
Width Splitting
Dowel Type Fastener
Connection Splitting Capacity
Language
English
Research Status
Complete
Series
Journal of Structural Engineering
Summary
The existing models for the prediction of the splitting failure of dowel-type connections loaded perpendicular to grain are determined generally based on crack growth of the entire member cross-section. These models can be appropriate for stocky or rigid fasteners installed through the full thickness of the wood member. However, for slender dowel-type fasteners such as timber rivets, particularly when the penetration depth of the fastener does not cover the whole member thickness, the crack formation is different. Observations from current tests in thick members show that the crack growth across the grain occurs to a depth corresponding to the effective embedment depth of the fastener and propagates along the grain until it reaches its unstable condition. The design method presented in this paper to predict the connection splitting capacity takes into account the observed two possible failure modes of wood: either partial or full width splitting. In the proposed method, the effect of geometry parameters such as connection width and length, fastener penetration depth, loaded and unloaded edge distances, end distance, and member thickness as observed by others are considered. Results of the tests undertaken with laminated veneer lumber (LVL) and glulam manufactured from New Zealand Radiata Pine (RP) and data available from literature confirm the validity of this new method and show that the proposed design approach can be used advantageously in comparison to other existing models for timber rivet connections under transverse loading.
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10 records – page 1 of 1.