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12 records – page 1 of 2.

Analysis and Tests of Lateral Resistance of Bolted and Screwed Connections of CLT

https://research.thinkwood.com/en/permalink/catalogue2956
Year of Publication
2022
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Huo, Liangliang
Zhu, Enchun
Niu, Shuang
Wu, Guofang
Organization
Harbin Institute of Technology
China Academy of Forestry
Editor
Ozarska, Barbara
Monaco, Angela
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Connections
Keywords
Lateral Resistance
European Yield Model
Bolt Connection
Screw Connectors
Emdedment Stress
Research Status
Complete
Series
Forests
Summary
The lateral resistance of dowel-type connections with CLT is related to its lay-up, species of the laminations and even the manufacture method. Treating the CLT as homogeneous material, current methods develop new equations through test results or make use of the existing equations for the embedment strength already used in design codes; thus, the lateral resistance of dowel-type connections of CLT can be calculated. This kind of approach does not take the embedment stress distribution into account, which may lead to inaccuracy in predicting the lateral resistance and yield mode of the dowel-type connections in CLT. In this study, tests of the bolted connections and the screwed connections of CLT were conducted by considering the effects of the orientation of the laminations, the thickness of the connected members, the fastener diameter and strength of the materials. The material properties including yield strength of the fasteners and embedment strength of the CLT laminations were also tested. Using analysis of the dowel-type connections of CLT by introducing the equivalent embedment stress distribution, equations for the lateral resistance of the connections based on the European Yield Model were developed. The predicted lateral resistance and yield modes were in good agreement with the test results; the correctness and the feasibility of the equations were thus validated.
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Analysis of Rotational Stiffness of the Timber Frame Connection

https://research.thinkwood.com/en/permalink/catalogue2763
Year of Publication
2020
Topic
Connections
Material
Glulam (Glue-Laminated Timber)
Application
Frames
Author
Johanides, Marek
Kubíncová, Lenka
Mikolášek, David
Lokaj, Antonín
Sucharda, Oldrich
Mynarcík, Petr
Publisher
MDPI
Year of Publication
2020
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Frames
Topic
Connections
Keywords
Rotational Stiffness
Frame Connection
Screw
Numerical Model
FEM
Finite Element Model
Mechanical Fasteners
Research Status
Complete
Series
Sustainability
Summary
Initially, timber was considered only as an easily accessible and processable material in nature; however, its excellent properties have since become better understood. During the discovery of new building materials and thanks to new technological development processes, industrial processing technologies and gradually drastically decreasing forest areas, wood has become an increasingly neglected material. Load-bearing structures are made mostly of reinforced concrete or steel elements. However, ecological changes, the obvious problems associated with environmental pollution and climate change, are drawing increasing attention to the importance of environmental awareness. These factors are attracting increased attention to wood as a building material. The increased demand for timber as a building material offers the possibility of improving its mechanical and physical properties, and so new wood-based composite materials or new joints of timber structures are being developed to ensure a better load capacity and stiffness of the structure. Therefore, this article deals with the improvement of the frame connection of the timber frame column and a diaphragm beam using mechanical fasteners. In common practice, bolts or a combination of bolts and pins are used for this type of connection. The subject of the research and its motivation was to replace these commonly used fasteners with more modern ones to shorten and simplify the assembly time and to improve the load capacity and rigidity of this type of frame connection.
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Composite CLT-Glulam Double-T Panels

https://research.thinkwood.com/en/permalink/catalogue2645
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Floors
Roofs
Organization
Fast + Epp
University of Northern British Columbia
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Floors
Roofs
Topic
Mechanical Properties
Connections
Keywords
Vibration
Stiffness Properties
Strength
Screw
Vibration Test
Monotonic Loading Tests
GCWood
Research Status
In Progress
Summary
To support the associated Sir Matthew Begbie Elementary School and Bayview Elementary School projects in pushing the boundaries forward for long-span floor and roof construction, this testing project aims to compare different connection approaches for composite connections between glulam and cross-laminated timber (CLT) – for vibration, stiffness, and strength. Working with the University of Northern British Columbia (UNBC), Fast + Epp aimed to complete a series of vibration and monotonic load tests on 30’ long full-scale double-T ribbed panels. The tests consisted of screws in withdrawal, screws in shear, and nominal screws clamping with glue. Both the strength and stiffness are of interest, including slip stiffness of each connection type. This physical testing was completed in January and February 2020, where the full composite strength of each system was reached. Initial data analysis has provided information for comparison with existing models for shear connection stiffness. Publications will follow in 2021.
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Cross-Laminated Timber Fasteners Solutions for Tall Wood Buildings

https://research.thinkwood.com/en/permalink/catalogue2197
Topic
Seismic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Floors
Shear Walls
Walls
Organization
TallWood Design Institute
Material
CLT (Cross-Laminated Timber)
Application
Floors
Shear Walls
Walls
Topic
Seismic
Connections
Keywords
Wall-to-Floor
Wall-to-Wall
Wall-to-Foundation
Strength Properties
Screw Connectors
Research Status
In Progress
Notes
Project contact is Arijit Sinha at Oregon State University
Summary
Constructing buildings with CLT requires development of novel panel attachment methods and mechanisms. Architects and engineers need to know the engineering strength properties of connected panels, especially in an earthquake prone area. This project will improve knowledge of three types of wall panel connections: wall-to-floor, wall-to-wall, and wall-to-foundation. Testing will determine the strength properties of metal connectors applied with diffferent types and sizes of screw fasteners. The data will be used to develop a modeling tool that engineers can use when designing multi-story buildings to be constructed with CLT panels.
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Development of an Innovative Hybrid Timber-Steel Moment-Resisting Frame for Seismic-Resistant Heavy Timber Structures

https://research.thinkwood.com/en/permalink/catalogue3012
Year of Publication
2016
Topic
Connections
Material
Steel-Timber Composite
Author
Gohlich, Ryan
Organization
Carleton University
Year of Publication
2016
Format
Thesis
Material
Steel-Timber Composite
Topic
Connections
Keywords
Hybrid Connection
Self-tapping screw
Moment-resisting Connection
Dynamic Time-History Analysis
Research Status
Complete
Summary
This study assesses the seismic performance of a new hybrid timber-steel moment-resisting connection for mid-rise heavy timber structures. This system consists predominantly of timber members, but utilizes a steel yielding link at the beam-column joint that improves seismic performance by replacing connection components that are susceptible to brittle failure with ductile steel elements. The steel-to-timber connection was made using self-tapping screws. By localizing all inelastic behaviour to a single ductile component, design with high seismic force reduction factors becomes justifiable. Four connections were tested; a majority of the plastic rotation was localized to the link, high levels of ductility were achieved, and the steel-to-timber connections remained undamaged. A numerical study was performed on a hybrid frame using the proposed connection, and an equivalent steel-only frame. Results showed that drifts and accelerations remained within allowable limits, indicating that well-detailed hybrid connections can result in seismic performance similar to steel-only frames.
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Dynamic Effects in Reinforced Timber Beams at Time of Timber Fracture

https://research.thinkwood.com/en/permalink/catalogue2303
Year of Publication
2015
Topic
Design and Systems
Application
Beams

Mechanical Characterization of Timber-to-Timber Composite (TTC) Joints with Self-Tapping Screws in a Standard Push-Out Setup

https://research.thinkwood.com/en/permalink/catalogue3068
Year of Publication
2020
Topic
Connections
Author
Bedon, Chiara
Sciomenta, Martina
Fragiacomo, Massimo
Organization
University of Trieste
University of L’Aquila
Publisher
MDPI
Year of Publication
2020
Format
Journal Article
Topic
Connections
Keywords
Timber-to-timber Composite
Push-out Test
Inclined Self-tapping Screw
Finite Element Method
Cohesive Zone Modelling
Boundaries
Friction
Sensitivity Study
Research Status
Complete
Series
Applied Sciences
Summary
Self-tapping screws (STSs) can be efficiently used in various fastening solutions for timber constructions and are notoriously able to offer high stiffness and load-carrying capacity, compared to other timber-to-timber composite (TTC) joint typologies. The geometrical and mechanical characterization of TTC joints, however, is often hard and uncertain, due to a combination of various influencing parameters and mechanical aspects. Among others, the effects of friction phenomena between the system components and their reciprocal interaction under the imposed design loads can remarkably influence the final estimates on structural capacity, in the same way of possible variations in the boundary conditions. The use of Finite Element (FE) numerical models is well-known to represent a robust tool and a valid alternative to costly and time consuming experiments and allows one to further explore the selected load-bearing components at a more refined level. Based on previous research efforts, this paper presents an extended FE investigation based on full three-dimensional (3D) brick models and surface-based cohesive zone modelling (CZM) techniques. The attention is focused on the mechanical characterization of small-scale TTC specimens with inclined STSs having variable configurations, under a standard push-out (PO) setup. Based on experimental data and analytical models of literature, an extended parametric investigation is presented and correlation formulae are proposed for the analysis of maximum resistance and stiffness variations. The attention is then focused on the load-bearing role of the steel screws, as an active component of TTC joints, based on the analysis of sustained resultant force contributions. The sensitivity of PO numerical estimates to few key input parameters of technical interest, including boundaries, friction and basic damage parameters, is thus discussed in the paper.
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Free
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Performance of Notched Connectors for CLT-Concrete Composite Floors

https://research.thinkwood.com/en/permalink/catalogue2656
Year of Publication
2020
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Author
Van Thai, Minh
Ménard, Sylvain
Elachachi, Sidi Mohammed
Galimard, Philippe
Publisher
MDPI
Year of Publication
2020
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Connections
Keywords
Notched Connections
Finite Element Model
Connectors
Deconstructable Connections
Screw
Research Status
Complete
Series
Buildings
Summary
CLT-concrete composite floor systems are a solution for timber buildings with a long-span floor. It yields a reduction of carbon footprint and even eco-friendly structure at the end of its service life. This study will evaluate the structural performance of notched connectors in the CLT-concrete composite floor, comprised of the serviceability stiffness, maximum load, and behavior at failure. The parameters of the test plan are the loaded edge length, the notch depth, the concrete thickness, and the screw length. Other secondary variables are also assessed, such as different loading sequences, speed of test, and timber moisture content. Experimental results prove that the performance of the connector depends significantly but not linearly on the notch depth and the length of the loaded edge. The connector with a deeper notch and a shorter heel will be stiffer and more robust, but it also tends to have a brittle rupture. The test results also help validate a solution for deconstructable connector systems. A nonlinear finite element model of the connector is built and validated versus the experimental results. It yields reasonably good predictions in terms of resistance and can capture the load-slip relationship.
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Prediction of Withdrawal Resistance for a Screw in Hybrid Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue2687
Year of Publication
2020
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Pang, Sung-Jun
Ahn, Kyung-Sun
Kang, Seog Goo
Oh, Jung-Kwon
Publisher
SpringerOpen
Year of Publication
2020
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Self-Tapping Screws
Withdrawal Resistance
Screw
Withdrawal Stiffness
Withdrawal Strength
Connections
Research Status
Complete
Series
Journal of Wood Science
Summary
The aim of this study was to predict the withdrawal resistance of a screw in hybrid cross-laminated timber (CLT) composed of two types of lamina layers. A theoretical model to predict the withdrawal resistance was developed from the shear mechanism between a screw and the layers in hybrid CLT. The parameters for the developed model were the withdrawal stiffness and strength that occurs when a screw is withdrawn, and the penetration depth of a screw in layers of a wood material. The prediction model was validated with an experimental test. Screws with two different diameters and lengths (Ø6.5 × 65 mm and Ø8.0 × 100 mm) were inserted in a panel composed of solid wood and plywood layers, and the withdrawal resistances of the screws were evaluated. At least 30 specimens for each group were tested to derive the lower 5th percentile values. As a result, the developed model predictions were 86–88% of the lower 5th percentile values of hybrid CLT from the properties of the lamina layer. This shows that the withdrawal resistance of hybrid CLT can be designed from the properties of its layer.
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Shear Properies of Timber-to-Timber Joints with Large Size Self-Tapping Screws

https://research.thinkwood.com/en/permalink/catalogue1003
Year of Publication
2014
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Author
Kobayashi, Kenji
Yasumura, Motoi
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Keywords
self-tapping screw
Shear Tests
Joints
Timber-to-Timber
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Cross Laminated Timber (CLT) is a new material for midrise timber structures. CLT panels made of Japanese species like Sugi (Cryptomeria japonica D.Don) are developed in Japan. Seismic resistance of CLT structures are mainly determined by the performances of panel-to-panel connections. One of the main fasteners for CLT connections is large size self-tapping screws. It is possible to use not only CLT panels but also glulam structures. But there are few data for these joints and not used so much in Japan. In this study, shear tests of timbet-to-timber joints including CLT panels with large size self-tapping screws and several material tests were conducted. And estimating equations of single shearing properties were validated. In this study, shear tests of timbet-to-timber joints including CLT panels with large size self-tapping screws and several material tests were conducted. And estimating equations of single shearing properties were validated. Estimation curves were fitted well with test curves. It is confirmed that estimating equations are valid for timber-to-timber connections of large size self-tapping screws.
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12 records – page 1 of 2.