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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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Dynamic Response of Tall Timber Buildings Under Service Load - The DynaTTB Research Program

https://research.thinkwood.com/en/permalink/catalogue3015
Year of Publication
2020
Topic
Acoustics and Vibration
Application
Wood Building Systems
Author
Abrahamsen, Rune
Bjertnæs, Magne
Bouillot, Jacques
Brank, Bostjan
Cabaton, Lionel
Crocetti, Roberto
Flamand, Olivier
Garains, Fabien
Gavric, Igor
Germain, Olivier
Hahusseau, Ludwig
Hameury, Stephane
Johansson, Marie
Johansson, Thomas
Ao, Wai Kei
Kurent, Blaž
Landel, Pierre
Linderholt, Andreas
Malo, Kjell
Manthey, Manuel
Nåvik, Petter
Pavic, Alex
Perez, Fernando
Rönnquist, Anders
Stamatopoulos, Haris
Sustersic, Iztok
Tulebekova, Saule
Organization
Norwegian University of Science and Technology
University of Exeter
University of Ljubljana
Linnaeus University
Year of Publication
2020
Format
Conference Paper
Application
Wood Building Systems
Topic
Acoustics and Vibration
Keywords
Timber Building
Wind Load
Discomfort
Modelling
Damping
Full Scale
Conference
International Conference on Structural Dynamics
Research Status
Complete
Summary
Wind-induced dynamic excitation is becoming a governing design action determining size and shape of modern Tall Timber Buildings (TTBs). The wind actions generate dynamic loading, causing discomfort or annoyance for occupants due to the perceived horizontal sway – i.e. vibration serviceability failure. Although some TTBs have been instrumented and measured to estimate their key dynamic properties (natural frequencies and damping), no systematic evaluation of dynamic performance pertinent to wind loading has been performed for the new and evolving construction technology used in TTBs. The DynaTTB project, funded by the Forest Value research program, mixes on site measurements on existing buildings excited by heavy shakers, for identification of the structural system, with laboratory identification of building elements mechanical features coupled with numerical modelling of timber structures. The goal is to identify and quantify the causes of vibration energy dissipation in modern TTBs and provide key elements to FE modelers. The first building, from a list of 8, was modelled and tested at full scale in December 2019. Some results are presented in this paper. Four other buildings will be modelled and tested in spring 2021.
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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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Moment-resisting beam-to-column timber connections with inclined threaded rods: Structural concept and analysis by use of the component method

https://research.thinkwood.com/en/permalink/catalogue3132
Year of Publication
2022
Topic
Connections
Author
Stamatopoulos, Haris
Malo, Kjell Arne
Vilguts, Aivars
Organization
Norwegian University of Science and Technology
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Topic
Connections
Keywords
Moment-resisting Connection
Threaded Rod
Rotational Stiffness
Research Status
Complete
Series
Construction and Building Materials
Summary
The use of moment-resisting frames with semi-rigid connections as a lateral load-carrying system in timber buildings can reduce the need for bracing with diagonal members or walls and allow for more open and flexible architecture. The overall performance of moment-resisting frames depends largely on the properties of their connections. Screwed-in threaded rods with wood screw thread feature high axial stiffness and capacity and they may be used as fasteners in beam-to-column, moment-resisting timber connections. In the present paper, a structural concept for a beam–to-column, moment-resisting timber connection based on threaded rods is presented and explained. Analytical expressions for the estimation of the rotational stiffness and the forces in the rods were derived based on a component-method approach. The analytical predictions for stiffness were compared to experimental results from full scale tests and the agreement was good.
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Parametric analyses and feasibility study of moment-resisting timber frames under service load

https://research.thinkwood.com/en/permalink/catalogue3023
Year of Publication
2021
Topic
Mechanical Properties
Application
Frames
Author
Vilguts, Aivars
Stamatopoulos, Haris
Malo, Kjell Arne
Organization
Norwegian University of Science and Technology
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Application
Frames
Topic
Mechanical Properties
Keywords
Moment-resisting Timber Frame
Serviceability
Acceleration
Lateral Displacement
Inter-Story Drift
Fundamental Eigen-frequency
Mode Shape
Research Status
Complete
Series
Engineering Structures
Summary
Over the last decades, the increasing urbanization and environmental challenges have created a demand for mid-rise and high-rise timber buildings in modern cities. The major challenge for mid-rise and high-rise timber buildings typically is the fulfillment of the serviceability requirements, especially limitation with respect to the wind-induced displacements and accelerations. The purpose of the present paper is to evaluate the feasibility and the limitations of moment-resisting timber frames under service load according to the present regulations. The parametric analyses investigate the effects of the rotational stiffness of beam-to-column and column-to-foundation connections, storey number and height, number and length of bays, column cross-section dimensions and spacing between frames on the overall serviceability performance of the frames. Elastic and modal analysis were carried out for a total of 17,800 planar moment-resisting timber frames with different parameters by use of Abaqus Finite Element (abbr. FE) software. Finally, the obtained results were used to derive simple expressions for the lateral displacement, maximum inter-story drift, fundamental eigen-frequency, mode shapes and acceleration.
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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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A theoretical study of the dynamic response of planar timber frames with semi-rigid moment-resisting connections subjected to wind loads

https://research.thinkwood.com/en/permalink/catalogue2960
Year of Publication
2021
Topic
Wind
Application
Frames
Author
Cao, Alex Sixie
Stamatopoulos, Haris
Organization
Norwegian University of Science and Technology
ETH Zurich
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Application
Frames
Topic
Wind
Keywords
Moment-resisting Timber Frames
Semi-rigid Connection
Wind-induced Vibrations
Time-domain Analysis
Frequency-domain Analysis
Serviceability
Tall Timber Buildings
Research Status
Complete
Series
Engineering Structures
Summary
The dynamic response of semi-rigid timber frames subjected to wind loads is investigated numerically in this paper. The dynamic response of more than one million unique frames with different parameters was assessed with the frequency-domain gust factor approach, which is currently adopted by Eurocode 1, and the time-domain generalized wind load method. In the generalized wind load method, the frames were simulated for three different wind velocities with five simulations per unique combination of parameters, resulting in more than twelve million simulations in total. Qualitative and quantitative observations of the dataset were made. Empirical expressions for the accelerations, displacements, and fundamental eigenfrequency were proposed by the use of nonlinear regression applied to the obtained numerical results and a frequency reduction factor was developed. The wind-induced accelerations obtained by the two methods were compared to the corresponding serviceability criteria according to ISO10137, providing insight about the feasibility of moment-resisting frames as a lateral load-carrying system for mid-rise timber buildings. Comparison between the theoretical gust factor approach and the generalized wind load method showed that the gust factor approach was nonconservative in most cases. Finally, the effect of uniform and non-uniform mass distributions was investigated, with a theoretical reduction in top-floor accelerations of 50% and 25% respectively.
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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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10 records – page 1 of 1.