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35 records – page 2 of 4.

Experimental Investigation on the Fire Resistance of Glued-In Rod Timber Joints with Heat Resistant Modified Epoxy Resin

https://research.thinkwood.com/en/permalink/catalogue2665
Year of Publication
2020
Topic
Fire
Connections
Material
Glulam (Glue-Laminated Timber)
Author
Luo, Liquan
Shi, Benkai
Liu, Weiqing
Yang, Huifeng
Ling, Zhibin
Publisher
MDPI
Year of Publication
2020
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Fire
Connections
Keywords
Fire Resistance
Glued-In Rod Joint
Glued-In Rod Timber Joint
Pull-Out Test
Heat Resistant
Modified Epoxy Resin
Adhesive
Research Status
Complete
Series
Materials
Summary
This paper presents an experimental evaluation of the fire resistance of glued-in rod timber joints using epoxy resin, with and without modification. A heat-resistant modified resin was designed by adding inorganic additives into the epoxy resin, aiming to improve the heat resistance. Joints that were made using the modified epoxy resin at room temperature showed a bearing capacity comparable to those with commercial epoxy resin. Twenty-one joint specimens with the modified epoxy resin and six with a commercial epoxy resin were tested in a fire furnace to evaluate the fire resistance. The main failure mode was the pull-out of the rod, which is typical in fire tests of this type of joints. As to the effects of the test parameters, this study considered the effects of adhesive types, sectional sizes, stress levels, and fireproof coatings. The test results showed that the fire resistance period of a joint can be evidently improved by modifying the resin and using the fireproof coating, as the improvements reached 73% and 35%, respectively, compared with the joint specimens with commercial epoxy resin. It was also found that, for all specimens, the fire resistance period decreased with an increase in the stress level and increased with an increase in the sectional sizes.
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Experimental investigations on the load-bearing behaviour of traditional and newly developed step joints for timber structures

https://research.thinkwood.com/en/permalink/catalogue2958
Year of Publication
2022
Topic
Mechanical Properties
Connections
Application
Trusses
Author
Braun, Matthias
Pantscharowitsch
Kromoser, Benjamin
Organization
University of Natural Resources and Life Sciences Vienna
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Application
Trusses
Topic
Mechanical Properties
Connections
Keywords
Timber Joints
Step-joint
Carpentry Joints
Research Efficiency
Research Status
Complete
Series
Construction and Building Materials
Summary
In this paper the load-bearing behaviour of traditional and newly developed timber-timber connections, multi-step and free formed, are analysed within an extensive investigation focusing on joint failure. DIC measurements allowed for an assessment of the initial behaviour of the systems and their specific failure modes. By comparing the stiffness and various load levels to those of typical joint designs the improved load-bearing behaviour of the proposed joints was demonstrated while defining the range of the obtained linear-elastic phase. The results show that the onset of failure, based on the ultimate load, strongly depends on the geometry of the joint.
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A finger-joint based edge connection for the weak direction of CLT plates

https://research.thinkwood.com/en/permalink/catalogue3149
Year of Publication
2022
Topic
Mechanical Properties
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Author
Tapia, Cristóbal
Claus, Marian
Aicher, Simon
Organization
University of Stuttgart
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Market and Adoption
Keywords
Bonded Edge Connection
Robotic Milling
Screw-gluing
Biaxiality
Finger-joint
Gap-filling PUR Adhesive
Research Status
Complete
Series
Construction and Building Materials
Summary
A new connection concept for joining cross-laminated timber (CLT) plates in their secondary direction is presented. The connection consists of two laminated veneer lumber (LVL) gusset plates with finger-joint-like profiles milled on one side which are glued onto the outermost layers of the CLT. It is demonstrated that the joint represents a stiff moment resistant connection, enabling the activation of the normally underutilized biaxiality of CLT plates and expanding the design freedom of architects and engineers. The concept was analyzed by means of analytical and finite element (FE) models for two geometry alternatives, differing in either a 2D or 3D tapered finger profile. The 3D tapered finger profile produced a stress reduction of around 5% in the region of stress concentration and a more even shear stress distribution on the bonded surface. Thereafter, four specimens were manufactured – two of each geometry alternative – and then tested in four- and three-point bending setups in order to assess the behavior at pure bending as well as at combined moment and shear loading, respectively. At pure bending, the studied connection delivered bending capacities of 100% of the characteristic value of the unjointed CLT material. For the case of moment and shear loading, the global capacity was determined by a bending failure in the CLT region subjected to maximum moment, while the joints remained unbroken. Measured deformations and strains during the tests validated the FE model, which can be used to further develop the connection concept, which allows for a full activation of the biaxial behavior of large-span CLT floors.
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Fire Tests on Finger-Jointed Timber Boards

https://research.thinkwood.com/en/permalink/catalogue170
Year of Publication
2014
Topic
Fire
Material
Glulam (Glue-Laminated Timber)
Author
Klippel, Michael
Frangi, Andrea
Organization
ETH Zurich
Year of Publication
2014
Format
Report
Material
Glulam (Glue-Laminated Timber)
Topic
Fire
Keywords
Adhesives
Strength
Finger-joint
Temperature
Fire Resistance
Research Status
Complete
Summary
This testing report summarises the experimental investigations on finger-jointed timber specimens, glued with different types of adhesives, loaded in tension and exposed to standard ISO-fire. The tests were performed as part of the project entitled “Fire safety of bonded structural timber elements” in the frame of a CTI-project (Commission for Technology and Innovation). The extensive testing programme on finger-jointed timber specimens was performed in cooperation with industry partners at the Swiss Federal Institute of Technology Zurich (ETH Zurich). The main aim of this research project is to clarify if the currently used design model for the fire resistance of bonded structural timber elements, such as glued-laminated timber, should consider the behaviour of adhesives at elevated temperatures. In this experimental study, different adhesives available on the market from adhesive manufacturer from Europe (such as Casco AG, Dynea AG, Jowat AG, Türmerleim AG, Purbond AG) were tested. Adhesives being used for structural applications as well as adhesives not certified according to current European testing standards for the use in structural applications were tested. The fire performance of 12 different adhesives - of type 1C PUR, MUF, PRF, EPI, PVAc, UF - were tested in a finger-jointed connection for cross-sections with a width of 80, 140 and 200 mm. In total, 49 fire tests were performed under ISO-fire exposure at the Swiss Federal Laboratories for Materials Testing and Research (EMPA) in Duebendorf/ Switzerland. Two tests were conducted with specimens equipped with thermocouples to determine the temperature distribution along the cross-section width. In the other tests, different parameters and their influence on the fire resistance were varied, such as the adhesive in the finger joint, the width of the specimen, the load level and the type of fire exposure on the testing lamella. The tests were performed in two test series in March and April, 2011 as well as in July and August, 2012. The second test series was extended by five additional tests with higher graded timber in August 2013. The main result from the first test series can be concluded as follows: The adhesives tested (2 x PUR, 1 x MUF) fulfil current approval criteria according to EN 301 (2013c) and EN 15425 (2008) for the use in load-bearing timber components in Europe. The adhesives fulfil at least the A7 test at 70°C according to EN 302-1 (2013a). Taking into account the failure pattern, no significant difference was observed between these adhesives. It could be shown that the higher loss of strength for some adhesives tested at elevated temperature does not necessarily lead to the same loss of strength in fire, since defects like knots may be dominant - depending on the strength class (grading). The main result from the second test series can be concluded as follows: No substantial difference was obtained for finger-jointed specimens glued with PRF and other structural adhesives. The PUR adhesive fulfilling the ASTM D7247 (2007) standard test at temperatures higher than 200 C did not reach a higher fire resistance than PUR adhesives which do not fulfil this standard. It was found that adhesives, which are used in structural timber members such as glued-laminated timber beams, need sufficient strength at lower temperatures than 200 C.This is especially explained by the steep temperature gradient typical for timber members such as glued-laminated timber. In addition to the fire tests, about 120 tensile tests on finger-jointed lamellas were performed at normal temperature. These lamellas were produced with the same types of adhesives as studied in the fire tests. The results of the whole investigation are summarised in this test report.
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The influence of inaccuracies in the production process on the load-bearing behaviour of timber step joints

https://research.thinkwood.com/en/permalink/catalogue3115
Year of Publication
2022
Topic
Connections
Application
Trusses
Author
Braun, Matthias
Kromoser, Benjamin
Organization
University of Natural Resources and Life Sciences Vienna
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Application
Trusses
Topic
Connections
Keywords
Timber Joints
Timber Truss
Step-joint
Carpentry Joints
Resource Efficiency
Research Status
Complete
Series
Construction and Building Materials
Summary
Inaccuracies within timber step joints are a perennial problem of the wood construction industry. Even perfectly constructed carpentry step joints can become imperfect due to a change in moisture content. The predominant question when looking at step joints with gaps is to what extent the load-bearing behaviour is influenced by these inaccuracies. The authors look beyond this question and investigate if intentionally manufactured gaps could have a positive influence on the load-bearing behaviour and the failure mode of regular and newly designed carpentry joints.
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Influence of inter-panel connections on vibration response of CLT floors due to pedestrian-induced loading

https://research.thinkwood.com/en/permalink/catalogue3340
Year of Publication
2023
Topic
Connections
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Milojevic, Marija
Racic, Vitomir
Marjanovic, Miroslav
Nefovska-Danilovic, Marija
Organization
University of Belgrade
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Connections
Acoustics and Vibration
Keywords
Walking Forces
Human-induced Vibrations
Single Surface Spline
Half-lapped Joint
Research Status
Complete
Series
Engineering Structures
Summary
Long-span cross-laminated timber (CLT) floors are typically an assembly of prefabricated CLT panels connected together on the site. The actual connections are commonly neglected in design calculations. Hence, a CLT floor is modelled either as a monolith slab or more frequently as a set of CLT panels with no connections at all. This paper presents a numerical study designed to examine the influence of two most common inter-panel connections, i.e. single surface spline and half-lapped joint, on vibration modes and vibration responses of a range of different CLT floors due to pedestrian-induced loading. Although the inter-panel connections are relatively complex in reality, they are modelled here as an equivalent 2D elastic strip between the CLT panels. This relatively simple yet robust model can be used with ease in design practice, regardless finite element (FE) software used to extract vibration modes of a CLT floor. The corresponding monolith floors and floors without inter-panel connections are studied for the comparison of the results. Vertical vibration responses are simulated for low-frequency and high-frequency floors using the corresponding walking force models given in a popular design guideline for footfall induced vibrations of civil engineering structures. Vibration responses were calculated for single pedestrian occupants and their walking paths parallel and perpendicular to the line of connection. The results showed that including the inter-panel connections in a FE model resulted in up to 2.5 higher RMS acceleration levels. Hence, the common practice of modelling CLT floors as monolith slabs or as a set of panels without connections should be left behind.
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Investigation Concerning Life Cycle Assessment of Worked Timber: Japanese Larch Glued Laminated Timber of Eastern Nagano Prefecture

https://research.thinkwood.com/en/permalink/catalogue961
Year of Publication
June 2014
Topic
Environmental Impact
Material
Glulam (Glue-Laminated Timber)
Author
Matsukata, Keisuke
Asano, Yoshiharu
Takamura, Hideki
Hayakawa, Yoshiro
Publisher
J-STAGE
Year of Publication
June 2014
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Environmental Impact
Keywords
Life-Cycle Assessment
Larch
Carbon
Finger joint
Research Status
Complete
Series
Japan Architectural Institute Technical Report
Summary
In a process before being finished in a sawing factory after felled in forest, we clarified the actual situation of the carbon income and expenditure with edge materials and the fuel, and calculated the carbon balance of the house made by Nagano’s local wood. In this report, we carried out the actual survey and a hearing investigation in the laminated lumber factory and, calculated carbon balance of Japanese larch finger joint wood and glued laminated timber of eastern Nagano prefecture.
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Investigation into the Hysteretic Performance of Self-Centering Timber Beam-to-Column Joints

https://research.thinkwood.com/en/permalink/catalogue1562
Year of Publication
2016
Material
Glulam (Glue-Laminated Timber)
Author
Wang, Kangli
Li, Zheng
He, Minjuan
Year of Publication
2016
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Keywords
China
Post-Tensioned
Self-Centering
Energy Dissipation
Joint
Cyclic Loading Tests
Hysteretic Behaviour
Moment-Resisting Capacity
Failure Mechanism
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 1540-1547
Summary
The seismic performance of a post-tensioned (PT) energy dissipating beam-to-column joint for glulam heavy timber structure is investigated in this paper. Such connection incorporates post-tensioned high-strength strand to provide self-centering capacity along with energy dissipating produced by a special steel cap, which is attached with the timber beam and also to prevent the end bearing failure of wood. The moment-rotation behaviour of the proposed posttensioned timber joint was investigated through a series of cyclic loading tests. The timber joint was loaded at the end of the beams to produce a moment at the joint, and the tests were conducted with three different post-tension forces in the steel strand. The hysteretic behaviour and self-centering capacity of the joint are evaluated based on the results from cyclic loading tests. The failure mechanism of the joint was illustrated through test observations, and the momentresisting capacity and energy dissipation of the joint were analysed with regard to various drift level. This research aims to provide possible solutions to minimize the residual deformation of heavy timber structure made of glulam in China.
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Laminated Veneer Lumber Hollow Cross-sections for Temporary Soil Nailing

https://research.thinkwood.com/en/permalink/catalogue2486
Year of Publication
2019
Topic
Design and Systems
Material
LVL (Laminated Veneer Lumber)
Application
Wood Building Systems
Author
Hirschmüller, Sebastian
Marte, Roman
Englberger, Alexander
Organization
Delft University of Technology
Year of Publication
2019
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Application
Wood Building Systems
Topic
Design and Systems
Keywords
Hollow Sections
Finger Joint
Large Scaled Tensile
Conference
International Scientific Conference on Hardwood Processing
Research Status
Complete
Summary
An innovative approach using laminated veneer lumber (LVL) hollow sections for temporary geotechnical slope stabilisation is being presented within this article. The use of circular laminated veneer lumber hollow sections as reinforcement elements in soil nailing walls demands load bearing elements, primarily loaded in tension, with a length up to 10 m. Thus finger-jointing was found to be an efficient method of a longitudinal load-carrying connection in combination with a minimized cross section reduction at the joint. This paper discusses the applicabiltiy of finger jointing on beech wood laminated veneer lumber hollow sections and presents the results of large scaled tensile under variaton of the joint arrangement.
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Lateral Resistance of Cross-Laminated Timber Panel-to-Panel Connections

https://research.thinkwood.com/en/permalink/catalogue1724
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Richardson, Benjamin
Hindman, Daniel
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Connections
Mechanical Properties
Keywords
Strength
Stiffness
Panel-to-Panel
Monotonic Loading
Cyclic Loading
Half-Lap
Butt-Joint
Steel Plate
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 4655-4662
Summary
Cross laminated timber (CLT) connections in shearwalls require an understanding of the shear strength and stiffness of panel-to-panel connections within the wall. This research measures the strength and stiffness of three different panel-to-panel CLT connections considering both monotonic and cyclic loading. Connections included a laminated veneer lumber (LVL) spline, a half-lap connection and a butt joint with overlapping steel plate. All connections were ductile in nature. The butt joint with steel plate demonstrated the highest connection strength of the connections tested. The cyclic stiffness of the laminated veneer lumber spline was less than the monotonic stiffness, while the halflap joint experienced a sharp drop in load after ultimate load was achieved. Full details of the monotonic and cyclic behaviour will be discussed, including load, stiffness and ductility terms.
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35 records – page 2 of 4.