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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
Country of Publication
United Kingdom
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
Language
English
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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The Heavy Timber Buckling-Restrained Braced Frame as a Solution for Commercial Buildings in Regions of High Seismicity

https://research.thinkwood.com/en/permalink/catalogue1651
Year of Publication
2016
Topic
Seismic
Design and Systems
Material
Solid-sawn Heavy Timber
Application
Wood Building Systems
Author
Blomgren, Hans-Erik
Koppitz, Jan-Peter
Díaz Valdés, Abel
Ko, Eric
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
Solid-sawn Heavy Timber
Application
Wood Building Systems
Topic
Seismic
Design and Systems
Keywords
Lateral Load Resisting System
Mid-Rise
High-Rise
US
Building Codes
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 3515-3524
Summary
Timber building construction has been traditionally utilized to reduce inertial demands in high seismic regions. Applications in the United States however, are often limited to low-rise buildings of light-wood construction with distributed load bearing shear walls. Recent advancements in timber technologies are pushing mass timber systems into larger commercial scale markets where steel and concrete systems dominate the landscape. In high seismic regions, mass timber buildings currently lack code-defined lateral force resisting systems. This paper presents a new lateral force resisting system concept, known as the Heavy Timber Buckling-Restrained Braced Frame. The system is conceived, although not limited, for application in mid and high-rise building timber construction, and is inspired by the unbonded steel brace technology today widely spread throughout Japan and the United States. In order to qualify the system for future implementation in building codes, the paper presents results from proof-of-concept component testing of a brace consisting of a steel core and a mechanically laminated glulam casing acting as the bucklingrestraint mechanism. As well, findings from a study for implementation at the building system level is provided in order to assess overall system performance, constructability, and detailing.
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Fire Resistance in American Heavy Timber Construction

https://research.thinkwood.com/en/permalink/catalogue1453
Year of Publication
2016
Topic
General Information
Material
Solid-sawn Heavy Timber
Application
Wood Building Systems
Author
Heitz, Jesse
Publisher
Springer, Cham
Year of Publication
2016
Country of Publication
Switzerland
Format
Book/Guide
Material
Solid-sawn Heavy Timber
Application
Wood Building Systems
Topic
General Information
Keywords
Historical Fire Performance
Language
English
Research Status
Complete
ISBN
978-3-319-32128-8
Summary
This volume presents a history of heavy timber construction (HTC) in the United States, chronicling nearly two centuries of building history, from inception to a detailed evaluation of one of the best surviving examples of the type, with an emphasis on fire resistance. The book does not limit itself in scope to serving only as a common history. Rather, it provides critical analysis of HTC in terms of construction methods, design, technical specifications, and historical performance under fire conditions. As such, this book provides readers with a truly comprehensive understanding and exploration of heavy timber construction in the United States and its performance under fire conditions.
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Repair and Reinforcement of Timber Columns and Shear Walls - A Review

https://research.thinkwood.com/en/permalink/catalogue867
Year of Publication
2015
Topic
Serviceability
Material
Solid-sawn Heavy Timber
Application
Shear Walls
Columns
Author
Chang, Wen-Shao
Publisher
ScienceDirect
Year of Publication
2015
Country of Publication
Netherlands
Format
Journal Article
Material
Solid-sawn Heavy Timber
Application
Shear Walls
Columns
Topic
Serviceability
Keywords
Reinforcement
Repair
Long-term
Language
English
Research Status
Complete
Series
Construction and Building Materials
Summary
Although it was found that most of the research foci were on reinforcement of timber connections and flexural members, columns and shear walls play a crucial role in the prevention of structural collapse. Recent trends to build taller timber structures, a demand for structures with larger span, and re-use of existing structures for different purposes have made reinforcement of timber columns and shear walls increasingly important. In addition, repair of damaged timber columns and shear walls so as to prevent further damage to the structures and elongate the life span of existing structures is also important. This paper provides an overview of techniques available to repair and strengthen timber columns and shear walls in both research and practice.
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Failure Modes and Reinforcement Techniques for Timber Beams – State of the Art

https://research.thinkwood.com/en/permalink/catalogue11
Year of Publication
2015
Topic
Serviceability
Material
Solid-sawn Heavy Timber
Application
Beams
Author
Harte, Annette
Franke, Bettina
Franke, Steffen
Publisher
ScienceDirect
Year of Publication
2015
Country of Publication
Netherlands
Format
Journal Article
Material
Solid-sawn Heavy Timber
Application
Beams
Topic
Serviceability
Keywords
Damage
Deterioration
Failure
Fasteners
Large Span
Loading
Reinforcement
Retrofit
Language
English
Research Status
Complete
Series
Construction and Building Materials
Summary
Highly loaded and large span timber beams are often used for halls, public buildings or bridges. Reinforcement of beams may be required to extend the life of the structure, due to deterioration or damage to the material/product or change of use. The paper summarises methods to repair or enhance the structural performance of timber beams. The main materials/products cross sections and geometries used for timber beam are presented. Furthermore, their general failure modes are described and typical retrofitting and reinforcement techniques are given. The techniques include wood to wood replacements, use of mechanical fasteners and additional strengthening materials/products.
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Application of Quasi-Brittle Material Model for Analysis of Timber Members

https://research.thinkwood.com/en/permalink/catalogue925
Year of Publication
2014
Material
Solid-sawn Heavy Timber
Author
Khorsandnia, Nima
Crews, Keith
Publisher
Taylor&Francis Online
Year of Publication
2014
Country of Publication
United Kingdom
Format
Journal Article
Material
Solid-sawn Heavy Timber
Keywords
ultimate load
Finite Element Model
Load-Deflection Response
Failure Load
Four Point Bending Test
Language
English
Research Status
Complete
Series
Australian Journal of Structural Engineering
Summary
Over the last two decades many constitutive models with different degrees of accuracy have been developed for analysis of sawn timber and engineered wood products. However, most of the existing models for analysis of timber members are not particularly practical to implement, owing to the large number of material properties (and associated testing) required for calibration of the constitutive law. In order to overcome this limitation, this paper presents details of 1D, 2D and 3D non-linear fi nite element (FE) models that take advantage of a quasi-brittle material model, requiring a minimum number of material properties to capture the load-defl ection response and failure load of timber beams under 4-point bending. In order to validate the model, four tapered timber piles with circular cross-section (two plains and two retrofi tted with steel jacket) were tested and analysed with the proposed 3D FE modelling technique; and a good correlation between experimentally observed and numerically captured ultimate load was observed. Consequently, it was concluded that the developed FE models used in conjunction with the quasi-brittle constitutive law were able to adequately capture the failure load and load-defl ection response of the fl exural timber elements.
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Development of a Heavy Timber Moment-Resisting Frame with Ductile Steel Links

https://research.thinkwood.com/en/permalink/catalogue1657
Year of Publication
2016
Topic
Connections
Mechanical Properties
Seismic
Material
Solid-sawn Heavy Timber
Application
Frames
Author
Gohlich, Ryan
Erochko, Jeffrey
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
Solid-sawn Heavy Timber
Application
Frames
Topic
Connections
Mechanical Properties
Seismic
Keywords
Mid-Rise
Self-Tapping Screws
Moment-Resisting
Strength
Stiffness
Ductility
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 3571-3580
Summary
To improve the seismic performance of mid-rise heavy timber moment-resisting frames, a hybrid timbersteel moment-resisting connection was developed that incorporates specially detailed replaceable steel yielding link elements fastened to timber beams and columns using self-tapping screws (STS). Performance of the connection was verified using four 2/3 scale experimental tests. The connection reached a moment of 142 kN m at the column face while reaching a storey drift angle of 0.05 rad. Two specimens utilizing a dogbone detail in the steel link avoided fracture of the link, while two specimens absent of the dogbone detail underwent brittle failure at 0.05 rad drift. All four test specimens met the acceptance criteria in the AISC 341-10 provisions for steel moment frames. The STS connections exhibited high strength and stiffness, and all timber members and self-tapping screw connections remained elastic. The results of the experimental program indicated that this hybrid connection is capable of achieving a ductility factor similar to that of a steel-only moment-resisting connection. This research suggests that the use of high ductility factors in the design of timber systems that use the proposed hybrid connection would be appropriate, thus lowering seismic design base shears and increasing structure economy.
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Heavy Laminated Timber Frames with Rigid Three-Dimensional Beam-To-Column Connections

https://research.thinkwood.com/en/permalink/catalogue499
Year of Publication
2014
Topic
Connections
Seismic
Material
Solid-sawn Heavy Timber
Application
Beams
Author
Kasal, Bohumil
Guindos, Pablo
Polocoser, Tiberiu
Heiduschke, Andreas
Urushadze, Shota
Pospisil, Stanislav
Publisher
American Society of Civil Engineers
Year of Publication
2014
Country of Publication
United States
Format
Journal Article
Material
Solid-sawn Heavy Timber
Application
Beams
Topic
Connections
Seismic
Keywords
Full Scale
Self-Tapping Screws
Cyclic Loads
Beam-to-Column
Language
English
Research Status
Complete
Series
Journal of Performance of Constructed Facilities
Summary
This article presents the seismic performance of a timber frame with three-dimensional (3D) rigid connections. The connections were made with self-tapping screws and hardwood blocks were used to support the beams. The frame was designed to resist high seismic excitations with the goal of controlling the drift. The moment-rotation characteristics of the connections were measured in the laboratory by applying static cyclic loads. The frame made of laminated wood beams and columns, and cross-laminated lumber deck, was subjected to seismic, white noise, snapback, and sinusoidal sweep excitations. The synthetic seismic excitation was designed to contain a considerable amount of energy close to the frame’s first natural frequency. The structure showed no significant damage up to a peak ground acceleration of 1.25g. Failure of the frame occurred due to shearing of the columns with a peak ground acceleration of 1.5g. The designed structure fulfilled with current serviceability limits up to 0.8g.
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Seismic Assessment of a Heavy-Timber Frame Structure with Ring-Doweled Moment-Resisting Connections

https://research.thinkwood.com/en/permalink/catalogue1383
Year of Publication
2018
Topic
Seismic
Connections
Material
Solid-sawn Heavy Timber
Application
Wood Building Systems
Author
Rodrigues, Leonardo
Branco, Jorge
Neves, Luís
Barbosa, André
Publisher
Springer Netherlands
Year of Publication
2018
Country of Publication
Netherlands
Format
Journal Article
Material
Solid-sawn Heavy Timber
Application
Wood Building Systems
Topic
Seismic
Connections
Keywords
Ring-Doweled Connections
Seismic Performance
Eurocode 5
Eurocode 8
Ductility
Probabilistic Approach
Q Factor
Fragility Curves
Language
English
Research Status
Complete
Series
Bulletin of Earthquake Engineering
ISSN
1573-1456
Summary
The performance of heavy-timber structures in earthquakes depends strongly on the inelastic behavior of the mechanical connections. Nevertheless, the nonlinear behavior of timber structures is only considered in the design phase indirectly through the use of an R-factor or a q-factor, which reduces the seismic elastic response spectrum. To improve the estimation of this, the seismic performance of a three-story building designed with ring-doweled moment resisting connections is analyzed here. Connections and members were designed to fulfill the seismic detailing requirements present in Eurocode 5 and Eurocode 8 for high ductility class structures. The performance of the structure is evaluated through a probabilistic approach, which accounts for uncertainties in mechanical properties of members and connections. Nonlinear static analyses and multi-record incremental dynamic analyses were performed to characterize the q-factor and develop fragility curves for different damage levels. The results indicate that the detailing requirements of Eurocode 5 and Eurocode 8 are sufficient to achieve the required performance, even though they also indicate that these requirements may be optimized to achieve more cost-effective connections and members. From the obtained fragility curves, it was verified that neglecting modeling uncertainties may lead to overestimation of the collapse capacity.
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Static and Dynamic Properties of Retrofitted Timber Beams Using Glass Fiber Reinforced Polymers

https://research.thinkwood.com/en/permalink/catalogue797
Year of Publication
2016
Topic
Design and Systems
Mechanical Properties
Material
Solid-sawn Heavy Timber
Application
Beams
Author
Bru, David
Baeza, Francisco Javier
Varona, Francisco
García-Barba, Javier
Ivorra, Salvador
Publisher
Springer Netherlands
Year of Publication
2016
Country of Publication
Netherlands
Format
Journal Article
Material
Solid-sawn Heavy Timber
Application
Beams
Topic
Design and Systems
Mechanical Properties
Keywords
Damping Ratio
Ductility
Natural Frequency
Glass Fiber Reinforced Polymer
Pine
Reinforcement
Static Properties
Dynamic Properties
Modal Analysis
Four Point Bending Test
Bending Strength
Language
English
Research Status
Complete
Series
Materials and Structures
ISSN
1871-6873
Summary
A study on the static and dynamic properties of sawn timber beams reinforced with glass fiber-reinforced polymer (GFRP) is reported in this paper. The experimental program is focused on the behavior of unidirectional wooden slabs, and the main objective is to fulfill the service state limit upon vibrations using GFRP when an architectonical retrofitting project is necessary. Two different typologies of reinforcement were evaluated on pine wood beams: one applied the composite only on the lower side of the beams, while the other also covered half of the beams depth. For the dynamic characterization, the natural frequency, damping ratio, and dynamic elastic modulus were measured using two different techniques: experimental modal analysis upon the whole beams; and bandwidth method using smaller samples of the same material. The static characterization consisted on four point bending tests, where elastic modulus, bending strength and ductility were assessed. The lower composite had better ductility and bending strength. On the other hand, the U-shaped laminate showed higher stiffness but also at a higher material cost. However, it allowed some ductility, i.e. compressive plasticity, even in the presence of hidden knots. Both dynamic techniques gave similar results and were capable of measuring the structure stiffness, even if short samples were used. Finally, the changes on dynamic properties because of the GFRP did not jeopardize the dynamic performance of the reinforced timber beams.
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10 records – page 1 of 1.