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13 records – page 1 of 2.

Analytical Model to Evaluate the Equivalent Viscous Damping of Timber Structures with Dowel-Type Fastener Connections

https://research.thinkwood.com/en/permalink/catalogue1893
Year of Publication
2012
Topic
Connections
Application
Frames
Author
Loss, Cristiano
Piazza, Maurizio
Zonta, Daniele
Year of Publication
2012
Format
Conference Paper
Application
Frames
Topic
Connections
Keywords
Equivalent Viscous Damping
Moment Resisting Joints
Dowel-Type Connections
Non-linear Dynamic Analysis
Metal Fasteners
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
July 16-19, 2012, Auckland, New Zealand
Summary
The Equivalent Viscous Damping (EVD) parameter is used to simplify the dynamic problem, passing from a non-linear solution of the system to a simple linear-elastic one. In the case of Direct Displacement-Based seismic Design (DDBD) methods, the EVD value allows direct design of structures, without an iterative computational process. This paper proposes a rational analytical formula to evaluate the EVD value of timber structures with dowel-type metal fastener connections. The EVD model is developed at the ultimate limit state, as a solution of the equilibrium problem related to an inelastic configuration. For a specific joint configuration, the EVD predicted via an analytical model was compared to experimental results. The proposed EVD model was validated using non-linear dynamic analysis on a portal frame, built with dowel-type fasteners arranged in two concentric crowns.
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Ductility of Dowelled New Zealand Douglas-Fir CLT Connections Under Monotonic and Cyclic Loading

https://research.thinkwood.com/en/permalink/catalogue2114
Year of Publication
2019
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Ottenhaus, Lisa-Mareike
Li, Minghao
Brown, J.
Ravn, C.
Scott, B.
Organization
University of Canterbury
Year of Publication
2019
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Connections
Keywords
Multi-Story
Douglas-Fir
Dowel-Type Connections
Dowels
Conference
Pacific Conference on Earthquake Engineering
Research Status
Complete
Summary
Cross-laminated Timber (CLT) is gaining popularity in Australasia as a building material for multi-storey structures. For multi-storey timber buildings located in seismic areas, designing strong but ductile hold-downs for CLT shear walls can be challenging and requires careful structural connection design. In this study, dowelled connections in New Zealand Douglas-Fir (D.Fir) CLT with inserted steel plates were experimentally investigated as a solution for hold-downs in multi-storey timber buildings. The dowel group spacing was varied for CLT3 (3-ply, 135 mm thick), CLT5 (5-ply, 175 mm thick) and CLT7 (7-ply, 275 mm thick) D.Fir CLT to investigate the spacing impact on ductility of the hold-down connections under both monotonic and quasi-static cyclic loading. These results were also compared with past similar testing of dowelled connections in 5-ply (150 mm) Radiata Pine CLT. A total of 12 monotonic and 36 quasi-static cyclic tests were carried out and it was observed that increased dowel spacing increases ductility with similar strength when compared to past more dense dowel spacing tests. Furthermore, to deter the onset of tension perpendicular to grain brittle failure, fully threaded screws and nuts were added to the dowelled connection and the impact of this is discussed.
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Ductility of Large-scale Dowelled CLT Connections under Monotonic and Cyclic Loading

https://research.thinkwood.com/en/permalink/catalogue2254
Year of Publication
2017
Topic
Connections
Material
CLT (Cross-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Shear Walls

Dynamic Behaviour of Dowel-Type Connections Under In-Service Vibration

https://research.thinkwood.com/en/permalink/catalogue884
Year of Publication
2013
Topic
Connections
Serviceability
Acoustics and Vibration
Material
Solid-sawn Heavy Timber
Application
Frames
Beams
Author
Reynolds, Thomas
Organization
University of Bath
Year of Publication
2013
Format
Thesis
Material
Solid-sawn Heavy Timber
Application
Frames
Beams
Topic
Connections
Serviceability
Acoustics and Vibration
Keywords
dowel-type connections
Embedment
Nonlinear Behaviour
Time Dependent Behaviour
Energy Dissipation
Portal Frames
Research Status
Complete
Summary
This study investigated the vibration serviceability of timber structures with dowel-type connections. It addressed the use of such connections in cutting-edge timber structures such as multi-storey buildings and long-span bridges, in which the light weight and flexibility of the structure make it possible that vibration induced by dynamic forces such as wind or footfall may cause discomfort to occupants or users of the structure, or otherwise impair its intended use. The nature of the oscillating force imposed on connections by this form of vibration was defined based on literature review and the use of established mathematical models. This allowed the appropriate cyclic load to be applied in experimental work on the most basic component of a dowel-type connection: a steel dowel embedding into a block of timber. A model for the stiffness of the timber in embedment under this cyclic load was developed based on an elastic stress function, which could then be used as the basis of a model for a complete connector. Nonlinear and time-dependent behaviour was also observed in embedment, and a simple rheological model incorporating elastic, viscoelastic and plastic elements was fitted to the measured response to cyclic load. Observations of the embedment response of the timber were then used to explain features of the behaviour of complete single- and multiple-dowel connections under cyclic load representative of in-service vibration. Complete portal frames and cantilever beams were tested under cyclic load, and a design method was derived for predicting the stiffness of such structures, using analytical equations based on the model for embedment behaviour. In each cyclic load test the energy dissipation in the specimen, which contributes to the damping in a complete structure, was measured. The analytical model was used to predict frictional energy dissipation in embedment, which was shown to make a significant contribution to damping in single-dowel connections. Based on the experimental results and analysis, several defining aspects of the dynamic response of the complete structures, such as a reduction of natural frequency with increased amplitude of applied load, were related to the observed and modelled embedment behaviour of the connections.
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Effect of Array on Tensile Load Carrying Capacity CLT Drift Pinned Joint

https://research.thinkwood.com/en/permalink/catalogue1532
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Nakashima, Shoichi
Kitamori, Akihisa
Araki, Yasuhiro
Isoda, Hiroshi
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Reduction Coefficients
Dowel-Type Connections
Drift Pinned Joint
Tensile Tests
Stiffness
Proportional Limit Load
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 772-779
Summary
A reduction coefficient is applied in usual design of multiple dowels type connections. The numbers of stiffeners in row is one of important factor to decide this coefficient. CLT drift pinned joint showed small orthotropy against in plane tensile load. Tensile tests of multiple drift pins joints were performed to evaluate the effect of array. Numbers of drift pins n in each specimen were same (n=12), but the arrangements were different (2 x 6, 3 x 4, 4 x 3, 6 x 2). Also the grain directions were parameters (0, 90 degrees). The reduction of initial stiffness and proportional limit load showed good agreement between theoretical prediction and experimental results.
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Embedment Strength of Cross-Laminated Timber for Smooth Dowel-type Fasteners

https://research.thinkwood.com/en/permalink/catalogue2118
Year of Publication
2019
Topic
Connections
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Dong, Weiqun
Li, Qiao
Zhang, Hao
Wang, Zhiqiang
Zhou, Jianhui
Gong, Meng
Year of Publication
2019
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Connections
Design and Systems
Keywords
Fasteners
Embedment Strength
Failure Modes
Embedment Tests
Dowel-Type Connections
Conference
International Conference on Advances in Civil Engineering and Materials
Research Status
Complete
Series
MATEC Web of Conferences
Summary
Embedment strength is a significant property in the dowel type connection in timber structure, i.e. cross-laminated timber (CLT). The CLT design properties are different from those of sawn timber (ST) and glued-laminated timber (GLT) because of the orthogonal structure, which may particularly have influence on the design of connections. The layup feature, i.e. the thickness ratio of transverse layer (TRTL) was considered as an effective factor on CLT embedment strength in this study, except for other factors, i.e. wood density, smooth dowel diameter, and loading angle. Approximate 660 embedment tests were performed according to ASTM D5764 half-hole test method. A few of existing design models for CLT embedment strength were evaluated using experimental data. It was found that different factors had different effect tendency and each factor had statistically significant impact on CLT embedment strength. The embedment strength and failure modes of CLT were obviously different from those of GLT due to the existence of transverse layer in CLT. The existing design equations should be improved. Based on the test results, a new design equation was proposed which had better prediction.
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Experimental characterisation of the moment-rotation behaviour of beam-beam connections using compressed wood connectors

https://research.thinkwood.com/en/permalink/catalogue3131
Year of Publication
2021
Topic
Connections
Author
Mehra, Sameer
O'Ceallaigh, Conan
Sotayo, Adeayo
Guan, Zhongwei
Harte, Annette M.
Organization
National University of Ireland Galway
University of Liverpool
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Topic
Connections
Keywords
Compressed Wood Connectors
Dowel-Type Connections
Eurocode 5
Moment Rotation Behaviour
Beam-beam Connections
Research Status
Complete
Series
Engineering Structures
Summary
The widespread use of energy-intensive metallic connectors and synthetic adhesives in modern timber construction has negative implications for the end-of-life disposal or re-use of the structural timber components. Therefore, it is favourable to substitute metallic connectors and synthetic adhesives with bio-based alternatives such as wood-based connectors. Recent studies have shown that densified or compressed wood (CW) with superior mechanical properties could be suitable for the manufacture of wood-based connectors in the form of CW dowels and CW plates. This study experimentally examines the moment-rotation behaviour of semi-rigid type timber-CW beam-beam connections under pure bending. The study also assesses the suitability of current design rules to predict the moment capacity of timber-CW connections. The comparative study has shown that the moment capacity of the timber-CW connection can be conservatively predicted from the characteristic load-carrying capacity of the connections calculated using the EC 5 strength equations.
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Experimental investigation of the moment-rotation behaviour of beam-column connections produced using compressed wood connectors

https://research.thinkwood.com/en/permalink/catalogue3104
Year of Publication
2022
Topic
Mechanical Properties
Connections
Material
DLT (Dowel Laminated Timber)
Author
Mehra, Sameer
O'Ceallaigh, Conan
Sotayo, Adeayo
Guan, Zhongwei
Harte M. Annette
Organization
National University of Ireland
University of Liverpool
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
DLT (Dowel Laminated Timber)
Topic
Mechanical Properties
Connections
Keywords
Compressed Wood
Moment-Rotation Behaviour
Dowel Type Connections
Research Status
Complete
Series
Construction and Building Materials
Summary
The use of timber in construction in medium–high rise construction has increased in recent years largely due to the significant innovation in engineered wood products and connection technology coupled with a desire to utilise more environmentally sustainable construction materials. While engineered wood products offer a low-carbon solution to the construction industry, the widespread use of adhesive and metallic fasteners often limits the recyclability of the structural components at the end of life of the structure and it may be beneficial to reduce this where possible. To establish the possibility of an all-wood connection solution, this preliminary study examines a series of beam-column connections designs to evaluate the relative performance of the different designs, which are connected with modified or compressed wood (CW) connectors. The connection designs are formed between glued-laminated beam and column members in the first instance and later examined when connecting dowel-laminated timber (DLT) members. The results show that significant moment capacity and rotational stiffness can be achieved for connections solely connected using CW fasteners. Furthermore, the all-wood solution utilising CW fasteners to connect DLT members has also demonstrated significant moment capacity and rotational stiffness capacity without the use of adhesive and metallic components.
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Fire Behaviour of Dowel-Type Timber Connection with Slotted In Steel Plates Under Bending and Shear

https://research.thinkwood.com/en/permalink/catalogue1772
Year of Publication
2016
Topic
Connections
Fire
Material
Glulam (Glue-Laminated Timber)
Author
Zhang, Shengdong
Wang, Wan
Fan, Xinhai
Year of Publication
2016
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Fire
Keywords
Dowel-Type Connections
Steel Plates
Bending
Shear
Failure Modes
Charring Rate
Ambient Temperature
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 5317-5324
Summary
Investigations showed that large timber members exposed to fire have excellent fire-resistance. But very little research has been done on the performance of connections in timber structures exposed to fire. The dowel-type connections with slotted-in steel plates have widely been used in timber structures, sometime as moment resisting...
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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
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
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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13 records – page 1 of 2.