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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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Multiple Tenons - Experimental Study on Load-Bearing Capacity and Deformation Characteristics

https://research.thinkwood.com/en/permalink/catalogue1530
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
Solid-sawn Heavy Timber
Author
Claus, Timo
Seim, Werner
Schröder, Bernd
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
Solid-sawn Heavy Timber
Topic
Connections
Mechanical Properties
Keywords
Joints
Tenons
Load Bearing Capacity
Deformation
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 733-739
Summary
Modern joinery machines are able to produce precise and complex wood-to-wood connections on a high prefabrication level. For this work, multiple tenon joints were tested to assess the load-bearing capacity and deformation characteristics. Four different geometries of tenon set-ups have been tested. The evaluation of the results shows significantly higher load capacities of multiple tenon joints compared to traditional mortise and tenon geometries. The deformation characteristics show that relocation of loads takes place if the bending capacity of the tenons is guaranteed. Failure of multiple tenon joints occurs with high deformations within the connection. The investigations show the high potential of multiple tenons compared to wood-to-wood connections used currently. Preliminary calculations of mortise and tenon joints show no satisfying accordance with experimental data.
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Identifying Incipient Decay in Douglas-fir Bridge Components using X-Ray Computerized Tomography

https://research.thinkwood.com/en/permalink/catalogue2350
Year of Publication
2019
Topic
Design and Systems
Moisture
Serviceability
Material
Glulam (Glue-Laminated Timber)
Solid-sawn Heavy Timber
Application
Bridges and Spans
Author
Senalik, Christopher
Wacker, James
Wang, Xiping
Wu, Xi
Year of Publication
2019
Country of Publication
United States
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Solid-sawn Heavy Timber
Application
Bridges and Spans
Topic
Design and Systems
Moisture
Serviceability
Keywords
X-ray Computerized Tomography
Wood Timber
Brown Rot Fungus
Incipient Decay
Language
English
Conference
International Nondestructive Testing and Evaluation of Wood Symposium
Research Status
Complete
Summary
In this report, wooden members of sizes typically used in bridge construction are examined using x-ray computerized tomography (CT) to determine the presence of internal decay. This report is part of an overall study in which Douglas-fir (Pseudotsuga menziesii) glue-laminated (glulam) beams and solid sawn timbers were inoculated with brown rot fungus, Fomitopsis pinicola, and exposed to aboveground conditions approximately 25 miles (40 km) north of Gulfport, Mississippi, USA. The goal of the overall study is to develop interior decay within the test specimens and then identify and characterize the decay using a variety of nondestructive testing (NDT) techniques. One NDT technique used is x-ray CT. The pixel brightness (PB) of CT scan images is proportional to the specific gravity (SG) at that location; high SG materials appear brighter whereas low SG materials appear darker. The consumption of wood by fungus decreases the wood SG; however, fungal progression takes place in areas where sufficient moisture is present. The presence of moisture increases wood SG as detected by the CT scan, which masks the effect of the fungal decay, which is a common co-occurrence with many NDT techniques. To identify incipient decay, it is necessary to examine the ring structure both within and outside of the area of moisture. Quantifying the extent of the decay requires correlating the PB to known SG values for both dry wood and wood of varying moisture content. In this report, the relationship between wood SG, moisture content, and PB was quantified.
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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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Wood-Based Beams Strengthened with FRP Laminates: Improved Performance with Pre-Stressed Systems

https://research.thinkwood.com/en/permalink/catalogue305
Year of Publication
2015
Topic
Design and Systems
Mechanical Properties
Material
Solid-sawn Heavy Timber
Author
Kliger, Robert
Haghani, Reza
Brunner, Maurice
Harte, Annette
Schober, Kay-Uwe
Organization
European Journal of Wood and Wood Products
Publisher
Springer Berlin Heidelberg
Year of Publication
2015
Country of Publication
Germany
Format
Journal Article
Material
Solid-sawn Heavy Timber
Topic
Design and Systems
Mechanical Properties
Keywords
Fibre-Reinforced Polymer
Pre-stressed
Bending
Reinforcement
Language
English
Research Status
Complete
Series
European Journal of Wood and Wood Products
ISSN
1436-736X
Summary
Using bonded fibre-reinforced polymer (FRP) laminates for strengthening wooden structural members has been shown to be an effective and economical method. In this paper, properties of suitable FRP materials, adhesives and two ways of strengthening beams exposed to bending moment are presented. Passive or slack reinforcement is one way of strengthening. The most effective way of such a strengthening was to place reinforcement laminates on both tension and compression side of the beam. However, the FRP material is only partially utilised. The second way is to apply pre-stressing in FRP materials prior to bonding to tension side of flexural members and this way was showed to provide the most effective utilisation of these materials. The state of the art of such a strengthening and various methods are discussed. Increasing the load-bearing capacity, introducing a pre-cambering effect and thus improving serviceability which often governs the design and reducing the amount of needed FRP reinforcement are some of the main advantages. A recent development on how to avoid the requirement for anchoring the laminates at the end of the beams to avoid premature debonding is shown and the advantage of such a system is described.
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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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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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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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8 records – page 1 of 1.