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11 records – page 1 of 2.

Brittle failure of laterally loaded self-tapping screw connections for cross-laminated timber structures

https://research.thinkwood.com/en/permalink/catalogue3120
Year of Publication
2022
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Author
Azinovic, Boris
Cabrero, José Manuel
Danielsson, Henrik
Pazlar, Tomaž
Organization
Slovenian National Building and Civil Engineering Institute
University of Navarra
Lund University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Keywords
Brittle Failure
Analytical Model
Overstrength
Research Status
Complete
Series
Engineering Structures
Summary
The performance of structural timber connections is of utmost importance since they control the global response of the building. A ductile failure mechanism on the global scale is desirable, especially in the design of structures in seismic areas, where dissipative components in which ductile failure modes need to be ensured are considered. Therefore, the knowledge of possible brittle failure modes of connections is crucial. The paper investigates the brittle failures of laterally loaded dowel-type connections in cross-laminated timber subjected to tensile load in a lap joint configuration through experimental investigations and analytical estimations. A set of 13 different test series has been performed with fully threaded self-tapping screws of 8 mm diameter and different lengths (40 to 100 mm) in cross-laminated timber composed of 3 or 5 layers (layer thickness range from 20 to 40 mm), giving rise to the activation of different brittle failure modes at different depths. Plug shear was among the most typically observed failure modes. A previously proposed model for the brittle capacity was applied to the tested connections at the characteristic level. As shown by the performed statistical analysis, the existing model is not reliable and mainly unconservative. A very low performance is observed (CCC = 0.299), but with a good correlation (c = 0.750) for the tests in the parallel direction. Further research work is required to improve the current model predictions and to gain a better understanding of the underlying resisting mechanisms.
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Determination of Coefficients of Friction for Laminated Veneer Lumber on Steel under High Pressure Loads

https://research.thinkwood.com/en/permalink/catalogue2822
Year of Publication
2021
Topic
Connections
Material
LVL (Laminated Veneer Lumber)
Application
Wood Building Systems
Author
Dorn, Michael
Habrova, Karolina
Koubek, Radek
Serrano, Erik
Organization
Linnaeus University
Czech University of Life Sciences Prague
Lund University
Publisher
Springer Nature
Year of Publication
2021
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Application
Wood Building Systems
Topic
Connections
Keywords
Static Friction
High Pressure
Angle-to-grain
Moisture Content
Steel
Research Status
Complete
Series
Friction
Summary
In this study, static coefficients of friction for laminated veneer lumber on steel surfaces were determined experimentally. The focus was on the frictional behaviors at different pressure levels, which were studied in combination with other influencing parameters: fiber orientation, moisture content, and surface roughness. Coefficients of friction were obtained as 0.10–0.30 for a smooth steel surface and as high as 0.80 for a rough steel surface. Pressure influenced the measured coefficients of friction, and lower normal pressures yielded higher coefficients. The influence of fiber angle was observed to be moderate, although clearly detectable, thereby resulting in a higher coefficient of friction when sliding perpendicular rather than parallel to the grain. Moist specimens contained higher coefficients of friction than oven-dry specimens. The results provide realistic values for practical applications, particularly for use as input parameters of numerical simulations where the role of friction is often wrongfully considered.
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Durable Timber Bridges - Final Report and Guidelines

https://research.thinkwood.com/en/permalink/catalogue2133
Year of Publication
2017
Topic
Design and Systems
Moisture
Serviceability
Material
Glulam (Glue-Laminated Timber)
Application
Bridges and Spans
Author
Pousette, Anna
Arne Malo, Kjell
Fortino, Stefania
Thelandersson, Sven
Organization
RISE - Research Institutes of Sweden
NTNU Norwegian University of Science and Technology
Lund University
VTT Technical Research Centre of Finland
Year of Publication
2017
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Bridges and Spans
Topic
Design and Systems
Moisture
Serviceability
Keywords
Timber Construction
Durability
Moisture Content
Research Status
Complete
Summary
This is the final report from the project DuraTB - Durable Timber Bridges. The goal of the project was to contribute to the development of sustainable timber bridges by making guidelines for moisture design and developing new and improved bridge concepts and details in terms of durability and maintenance aspects. In this report the analyzes, surveys, results and guidelines are described. More detailed descriptions are referred to the many publications that the project has delivered.
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Evaluating Laboratory Measurements for Sound Insulation of Cross-Laminated Timber (CLT) Floors: Configurations in Lightweight Buildings

https://research.thinkwood.com/en/permalink/catalogue3157
Year of Publication
2022
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Vardaxis, Nikolaos-Georgios
Hagberg, Delphine Bard
Dahlström, Jessica
Organization
Lund University
Editor
Park, Junhong
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Airborne Sound
Impact Noise
Sound Insulation
Research Status
Complete
Series
Applied Sciences
Summary
Cross-laminated timber (CLT) floors with supplementary layers or floating floors comprise a common solution in new multistory timber structures. However, bare CLT components provide poor sound insulation, especially in low frequencies during structure-borne sound propagation. Thus, floor configurations in wooden buildings deploy more layers for improved acoustic behavior. Twelve contemporary CLT floors were analyzed after laboratory measurements of airborne sound reduction and impact sound transmission utilizing the following indicators: Rw, Rw, 100, Rw, 50, Ln,w, Ln,w,100, and Ln,w,50 (per ISO 10140, ISO 717). An increase in sound insulation was achieved thanks to added total mass and thickness, testing layers of the following: elastic mat for vibration isolation, wool insulation, gypsum boards, plywood, concrete screed, and wooden parquet floor. The results indicate that multilayered CLT floors can provide improvements of up to 22 dB for airborne sound and 32 dB for impact sound indicators compared with the bare CLT slab. Floating floor configurations with dry floor solutions (concrete screed) and wooden parquet floors stand out as the optimal cases. The parquet floor provides a 1–2 dB improvement only for impact sound indicators in floating floor setups (or higher in three cases).
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Glued Laminated Timber Space Truss Systems

https://research.thinkwood.com/en/permalink/catalogue244
Year of Publication
2012
Topic
Design and Systems
Connections
Material
Glulam (Glue-Laminated Timber)
Application
Frames
Author
Moggio, Nicola
Organization
Lund University
Year of Publication
2012
Format
Thesis
Material
Glulam (Glue-Laminated Timber)
Application
Frames
Topic
Design and Systems
Connections
Keywords
Space Frames
Research Status
Complete
Summary
The research is directed to explore the possible applications of the space frames system in the field of wooden construction, the proposed construction technology can provide ample opportunity even for timber engineering. The aim of the thesis is to prove the possible application of the timber material considering that the design of wood structures is very complex and requires detailed theoretical knowledge accompanied by the intuition and the ability which comes from an understanding of the critical points of the structures. The work is organized into several parts that try to consider all the thematic relating to the design of the specific construction technology and the material particularities.
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Improved low-frequency performance of cross-laminated timber floor panels by informed material selection

https://research.thinkwood.com/en/permalink/catalogue2961
Year of Publication
2021
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Persson, Peter
Flodén, Ola
Danielsson, Henrik
Peplow, Andrew
Andersen, Lars Vabbersgaard
Organization
Lund University
Aarhus University
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Vibroacoustic Response
Floor Vibration
Wood Species
Strength Class
Finite Element Method (FEM)
Research Status
Complete
Series
Applied Acoustics
Summary
The paper demonstrates improved structural low-frequency vibroacoustic performance of cross-laminated timber (CLT) floor panels by informed selection of the wood material. The use of wood species and strength classes that are not traditionally assigned to CLT panels was investigated in order to study their influence on dynamic characteristics and vibroacoustic response metrics. The potential of each of the orthotropic material properties to alternate the vibration response was examined to determine the governing parameters of the low-frequency vibroacoustic performance. The effects on transfer mobility response functions, and eigenfrequencies and mode shapes were used for a rigorous performance study of the panels. It was found that using laminations with stiffness properties typical for hardwoods ash, beech, and birch can significantly improve the performance of a CLT floor panel, and they outperform laminations of typical softwood strength classes.
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A Numerical Study of the Stiffness and Strength of Cross-Laminated Timber Wall-to-Floor Connections under Compression Perpendicular to the Grain

https://research.thinkwood.com/en/permalink/catalogue2839
Year of Publication
2021
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Author
Akter, Shaheda
Schweigler, Michael
Serrano, Erik
Bader, Thomas
Organization
Linnaeus University
Lund University
Editor
Brandner, Reinhard
Publisher
MDPI
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Topic
Connections
Mechanical Properties
Keywords
Parametric Study
Perpendicular to the Grain
Elasto-Plastic Behaviour
Numerical Modeling
Research Status
Complete
Series
Buildings
Summary
The use of cross-laminated timber (CLT) in multi-story buildings is increasing due to the potential of wood to reduce green house gas emissions and the high load-bearing capacity of CLT. Compression perpendicular to the grain (CPG) in CLT is an important design aspect, especially in multi-storied platform-type CLT buildings, where CPG stress develops in CLT floors due to loads from the roof or from upper floors. Here, CPG of CLT wall-to-floor connections are studied by means of finite element modeling with elasto-plastic material behavior based on a previously validated Quadratic multi-surface (QMS) failure criterion. Model predictions were first compared with experiments on CLT connections, before the model was used in a parameter study, to investigate the influence of wall and floor thicknesses, the annual ring pattern of the boards and the number of layers in the CLT elements. The finite element model agreed well with experimental findings. Connection stiffness was overestimated, while the strength was only slightly underestimated. The parameter study revealed that the wall thickness effect on the stiffness and strength of the connection was strongest for the practically most relevant wall thicknesses between 80 and about 160 mm. It also showed that an increasing floor thickness leads to higher stiffness and strength, due to the load dispersion effect. The increase was found to be stronger for smaller wall thicknesses. The influence of the annual ring orientation, or the pith location, was assessed as well and showed that boards cut closer to the pith yielded lower stiffness and strength. The findings of the parameter study were fitted with regression equations. Finally, a dimensionless ratio of the wall-to-floor thickness was used for deriving regression equations for stiffness and strength, as well as for load and stiffness increase factors, which could be used for the engineering design of CLT connections.
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Prefabricated Timber-Concrete Composite System

https://research.thinkwood.com/en/permalink/catalogue910
Year of Publication
2012
Topic
Design and Systems
Mechanical Properties
Connections
Material
Timber-Concrete Composite
Application
Floors
Author
Moar, Franco
Organization
Lund University
Year of Publication
2012
Format
Thesis
Material
Timber-Concrete Composite
Application
Floors
Topic
Design and Systems
Mechanical Properties
Connections
Keywords
FE model
Bending Tests
Withdrawal Tests
Compression Tests
Self-Tapping Screws
Prefabrication
Research Status
Complete
Summary
Timber-concrete composite structures were originally developed for upgrading existing timber oors, but during last decades, they have new applications in multistorey buildings. Most of the research performed on these structures has focused on systems in which wet concrete is cast on top of timber beams with mounted connectors. Recently investigations on composite systems were performed at Luleå University of Technology in Sweden, in which the concrete slab is prefabricated off-site with the connectors already embedded and then connected on-site to the timber joists. Similar studies have been carried out also on timber-concrete composite structures with prefabricated FRC slabs at Lund University in Sweden. Two kinds of shear connectors were incorporated in the prefabricated FRC concrete slabs. These last systems can be considered globally as partially prefabricated structures because only the slabs were cast off-site with already inserted shear connectors and then the connection with the timber beams is done on the building site. An innovative composite system for floor applications is presented in this thesis. The entire structure is prefabricated off-side, transported and direct mounted to the building on site, that can be seen as full prefabricated structures. Noticeable benefits of a full prefabricated structure are that the moving work from the building site to the workshop reduces construction costs, is more simple and fast of manufacture and erect, and of sure, has better quality, that means more durability. Self-tapping full-threaded screws to connect concrete slabs to timber beam were used. Dimensions of the composite beams and the spacing between the screws has been chosen by discussing different FE model in order to reach the optimal solution. The experimental campaign included: (i) two short-time bending tests carried out on two dierent full-scale specimens, (ii) dynamic tests conducted on one full-scale specimen, (iii) long-time bending test carried out on one full-scale specimen, (iv) compression tests on three cubes of concrete, (v) nine withdrawal tests of the screws with different depth in the concrete. The results of the experimental tests show that the composite beams have a very high level of resistance and stiffness and also allow to reach a high degree of efficiency. Last, comparisons between FE results, analytical calculations and experimental values have been performed and from them it can be concluded that FE model and theoretical calculations well interpret the behavior of the composite structure and provide reliable results.
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Strength and Stiffness of Cross Laminated Timber at In-Plane Beam Loading

https://research.thinkwood.com/en/permalink/catalogue2233
Year of Publication
2017
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Beams

The strength of Glulam Beams with Holes - A Probabilistic Fracture Mechanics Method and Experimental Tests

https://research.thinkwood.com/en/permalink/catalogue2238
Year of Publication
2009
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams

11 records – page 1 of 2.