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Connections with Threaded Rods in Moment Resisting Frames

https://research.thinkwood.com/en/permalink/catalogue1495
Year of Publication
2016
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Application
Frames
Author
Arne Malo, Kjell
Stamatopoulos, Haris
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Frames
Topic
Mechanical Properties
Connections
Keywords
Moment Resistance
Threaded Rods
Beam Column Connection
Rotational Stiffness
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 200-208
Summary
Building owners often state requirements that new buildings shall have open and flexible architecture in order to allow flexible use and future changes. A way to improve timber buildings in that direction is to increase the stiffness of the connections between horizontal and vertical members of the structural systems. This paper presents some numerical and analytical considerations with respect to the stiffness requirements for moment resisting timber connections. It also presents experimental tests and results for a moment resisting connection with inclined threaded rods installed in predrilled holes.
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The Effect of Depth and Diameter of Glued-In Rods on Pull-Out Connection Strength of Bamboo Glulam

https://research.thinkwood.com/en/permalink/catalogue1451
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
Other Materials
Author
Yan, Yan
Liu, Huanrong
Zhang, Xiubiao
Wu, Heng
Huang, Yun
Organization
Anhui Agricultural University
Publisher
Springer Japan
Year of Publication
2016
Format
Journal Article
Material
Other Materials
Topic
Connections
Mechanical Properties
Keywords
Bamboo
Steel Connections
Pullout Tests
Glued-In Rods
Threaded Rods
Pull-Out Strength
Adhesives
Failure Modes
Research Status
Complete
Series
Journal of Wood Science
Summary
In order to explore bamboo glulam utilization in structure construction, the adhesive bonded steel connection of bamboo glulam was investigated in this study. By carrying out both-end pullout tests on glued-in threaded rods in bamboo glulam, the effects of depth and diameter of embedded rods in bamboo glulam on the pullout strength and the failure modes were discussed. Results showed that threaded rods fracture and adhesive interface failure were the two main different failure modes in the tests. The pullout peak load of both-end glued-in rods in bamboo glulam increased with the diameter and the embedded length of the threaded rods. To satisfy tensile load of the glued threaded rods (quality 4.8) used in the connections between engineering structural materials, the slenderness ratio (the ratio of depth and diameter of glued-in threaded rods) equal to 10 or over was necessary.
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Effect of Rod-to-Grain Angle on Capacity and Stiffness of Axially and Laterally Loaded Long Threaded Rods in Timber Joints

https://research.thinkwood.com/en/permalink/catalogue1371
Year of Publication
2018
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Cepelka, Martin
Arne Malo, Kjell
Stamatopoulos, Haris
Publisher
Springer Berlin Heidelberg
Year of Publication
2018
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Threaded Rods
Axial Loads
Lateral Loads
Rod-to-Grain
Joints
Boundary Conditions
Load-to-Rod
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
Long threaded rods have recently been widely used as a reinforcement of glued laminated timber in perpendicular to the grain direction. The recent research has thus focused mainly on the withdrawal properties of the threaded rods in the axial direction. Utilizing their large withdrawal stiffness and strength, the threaded rods can also effectively be used as connectors in moment resisting timber joints. Yet, in joints, the threaded rods are often imposed to a non-axial loading, due to inclination of the rod axis to the grain as well as loading direction different from the rod axis. No design models are currently available for the combined axial and lateral loading of the threaded rods. In the present work, the effects of the rod-to-grain and load-to-rod angles on capacity and stiffness of the threaded rods are investigated by use of experiments and finite element models. Based on those, analytical expressions for determining stiffness and capacity of axially and laterally loaded threaded rods are proposed, intended as a basis for practical joint design. Furthermore, effect of various boundary conditions applied at the rod-ends is studied.
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Effects of Changes in Moisture Content in Reinforced Glulam Beams

https://research.thinkwood.com/en/permalink/catalogue1173
Year of Publication
2014
Topic
Moisture
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Dietsch, Philipp
Kreuzinger, Heinrich
Winter, Stefan
Year of Publication
2014
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Moisture
Mechanical Properties
Keywords
Reinforcement
Threaded Rods
Moisture Induced Stresses
Finite Element Method
Moisture Content
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Reinforcement in glulam beams in form of screws or rods can restrict the free shrinkage or swelling of the wood material. The objective of the project presented was to evaluate the influence of such reinforcement on the magnitude of moisture induced stresses. For this purpose, experimental studies were carried out in combination with analytical considerations on the basis of the finite-element method. Taking into account the influence of relaxation processes, the results indicate that a reduction of timber moisture content of 3 - 4 % around threaded rods, positioned perpendicular to the grain, can lead to critical stresses with respect to moisture induced cracks. In addition, a substantial mutual influence of adjacent reinforcing elements has been identified. A reduction of the distance between the reinforcement thus results in a lower tolerable reduction of timber moisture content around the reinforcement.
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Self-Tapping Screws and Threaded Rods as Reinforcement for Structural Timber Elements - A State-Of-The-Art Report

https://research.thinkwood.com/en/permalink/catalogue448
Year of Publication
2015
Topic
Connections
Serviceability
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Author
Dietsch, Philipp
Brandner, Reinhard
Publisher
ScienceDirect
Year of Publication
2015
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Topic
Connections
Serviceability
Keywords
Reinforcement
Threaded Rods
Self-Tapping Screws
Shear Stress
Europe
Research Status
Complete
Series
Construction and Building Materials
Summary
In timber engineering, self-tapping screws, optimized primarily for axial loading, represent the state-of-the-art in fastener and reinforcement technology. Their economic advantages and comparatively easy handling make them one of the first choices for application in both domains. This paper focuses on self-tapping screws and threaded rods applied as reinforcement, illustrating the state-of-the-art in application and design approaches in Europe, in conjunction with numerous references for background information. With regard to medium to large span timber structures which are predominately erected by using linear timber members, from e.g. glued laminated timber, the focus of this paper is on their reinforcement against stresses perpendicular to grain as well as shear. However, latest findings with respect to cross laminated timber are included as well.
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A study on beam-to-column moment-resisting timber connections under service load, comparing full-scale connection testing and mock-up frame assembly

https://research.thinkwood.com/en/permalink/catalogue3116
Year of Publication
2022
Topic
Connections
Application
Frames
Author
Vilguts, Aivars
Nesheim, Sveinung Ørjan
Stamatopoulos, Haris
Malo, Kjell Arne
Organization
Norwegian University of Science and Technology
Publisher
Springer
Year of Publication
2022
Format
Journal Article
Application
Frames
Topic
Connections
Keywords
Moment-resisting Connection
Semi-rigid Connection
Screwed-in Threaded Rods
Experimental Modal Analysis
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
A new timber frame structural system consisting of continuous columns, prefabricated hollow box timber decks and beam-to-column moment-resisting connections is investigated. The hollow box timber decks allow long spans with competitive floor height and efficient material consumption. To achieve long spans, semi-rigid connections at the corners of deck elements are used to join the columns to the deck elements. In the present paper, experimental investigations of a semi-rigid moment-resisting connection and a mock-up frame assembly are presented. The semi-rigid connection consists of inclined screwed-in threaded rods and steel coupling parts, connected with friction bolts. Full-scale moment-resisting timber connections were tested under monotonic and cyclic loading to quantify rotational stiffness, energy dissipation and moment resistance. The mock-up frame assembly was tested under cyclic lateral loading and with experimental modal analysis. The lateral stiffness, energy dissipation, rotational stiffness of the connections and the eigen frequencies of the mock-up frame assembly were quantified based on the experimental tests in combination with a Finite Element model, i.e., the model was validated with experimental results from the rotational stiffness tests of the beam-to-column connections. Finally, the structural damping measured with experimental modal analysis was evaluated and compared with FE model using the material damping of timber parts and equivalent viscous damping of the moment-resisting connections.
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Withdrawal of Axially Loaded Connectors from Timber Elements - Theory and Validation

https://research.thinkwood.com/en/permalink/catalogue639
Year of Publication
2014
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Stamatopoulos, Haris
Arne Malo, Kjell
Year of Publication
2014
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Axially Loaded Connectors
Withdrawal Capacity
Stiffness
threaded rods
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Connections consisting of axially loaded connectors embedded in timber elements can be a strong and competitive alternative to dowel-type connections. Such connections combine high capacity and stiffness. However, especially in the case of screwed-in threaded rods, the up-to date theoretical models and available experimental results are limited. In this paper, a general theoretical model that predicts the withdrawal capacity and stiffness of connections with axially loaded connectors is presented. The model is validated with an experimental study of withdrawal of threaded rods from glulam elements.
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Withdrawal of Pairs of Threaded Rods with Small Edge Distances and Spacings

https://research.thinkwood.com/en/permalink/catalogue1395
Year of Publication
2017
Topic
Mechanical Properties
Connections
Material
Glulam (Glue-Laminated Timber)
Author
Stamatopoulos, Haris
Malo, Kjell Arne
Publisher
Springer Berlin Heidelberg
Year of Publication
2017
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Connections
Keywords
Threaded Rods
Withdrawal Capacity
Stiffness
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
An experimental investigation on withdrawal of pairs of screwed-in threaded rods embedded in glued-laminated timber elements is presented in this paper. Specimens with varying angles between the rod axis and the grain direction (a = 15°, 30°, 60°, 90°) and 2 different configurations with respect to edge distances and spacings were tested. The diameter and the embedment length of the rods were 20 and 450 mm, respectively. The threaded rods were embedded in a row perpendicular to the plain of the grain. The edge distances and spacings were smaller than the minimum requirements according to Eurocode 5. The withdrawal capacity of pairs of rods was compared to the withdrawal capacity of single rods and the effective number, n ef , was found to be in the range 1.72–1.94, despite the small edge distances and spacings. Based on the experimental results obtained, a simple approximating expression was derived for n ef . An analytical model based on Volkersen theory with an idealized bi-linear constitutive relationship was used to estimate the withdrawal capacity and stiffness. The analytical estimations were in good agreement with the experimental results. Finally, the withdrawal stiffness was estimated by use of finite element simulations. The numerical estimations for the withdrawal stiffness were also in good agreement with the experimental results.
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Withdrawal Properties of Threaded Rods Embedded in Glued-Laminated Timber Elements

https://research.thinkwood.com/en/permalink/catalogue217
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Stamatopoulos, Haris
Organization
Norwegian University of Science and Technology
Year of Publication
2016
Format
Thesis
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Withdrawal Properties
Threaded Rods
Finite Element Model
Research Status
Complete
Summary
There is a complete lack of guidelines for the estimation of the withdrawal stiffness of threaded rods with larger diameters. Moreover, Eurocode 5 imposes a limitation to the angle between the rod-axis and the grain direction (a = 30°) without taking into account that splitting may be prevented by reinforcement. The lack of knowledge of proper design, documentation of mechanical behaviour, design guidelines and design codes for threaded rods are barriers for the development of timber connections with these fasteners. The withdrawal properties (capacity and stiffness) of axially loaded threaded rods were investigated in the present thesis by use of experimental, analytical and numerical methods. An overview of the background information and research on withdrawal of screws and threaded rods is presented in Part I of the present thesis. Part II consists of 4 appended papers where the findings of this Ph.D. project are presented. Part III consists of 3 appendices where some analytical remarks together with the detailed experimental and numerical results are presented. According to experimental observation, the specimens exhibited high withdrawal capacity and stiffness (without initial soft response). Based on the experimental results, the necessary input parameters for the analytical method were quantified. In particular, simple expressions for the mean and 5%-percentile withdrawal strength, the shear stiffness and the brittleness were developed. In general, the analytical estimations and the experimental results were in good agreement. Numerical estimations overestimated stiffness especially for small angles and short embedment lengths; however this overestimation was smaller in the case of longer rods. Finally, the experimental results from tests with pairs of rods showed that the effectiveness per each rod was quite high, despite the fact that rods were placed with small edge distances and spacings.
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9 records – page 1 of 1.