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17 records – page 1 of 2.

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
Author
Danielsson, Henrik
Organization
Lund University
Year of Publication
2009
Format
Thesis
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Holes
Strength
Research Status
Complete
Summary
This thesis deals with experimental tests and methods for strength analysis of glulam beams with holes. Test results and methods for strength analysis available in literature are compiled and discussed. The methods considered comprise both code strength design methods and more general methods for strength analysis. New strength tests of beams with quadratic holes with rounded corners are presented. The test programme included investigations of four important design para\-meters: material strength class, bending moment to shear force ratio, beam size and hole placement with respect to beam height. One important finding from these tests is the strong beam size influence on the strength. This finding is in line with previous test results found in literature but the beam size effect is however not accounted for in all European timber engineering codes. A probabilistic fracture mechanics method for strength analysis is presented. The method is based on a combination of Weibull weakest link theory and the mean stress method which is a generalization of linear elastic fracture mechanics. Combining these two methods means that the fracture energy and the stochastic nature of the material properties are taken into account. The probabilistic fracture mechanics method is consistent with Weibull weakest link theory in the sense that the same strength predictions are given by these two methods for an ideally brittle material. The probabilistic fracture mechanics method is also consistent with the mean stress method in the sense that the same strength predictions are given by these two methods for a material with deterministic material properties. A parameter study of the influence of bending moment to shear force ratio, beam size, hole placement with respect to beam height and relative hole size with respect to beam height is presented for the probabilistic fracture mechanics method. Strength predictions according to the probabilistic fracture mechanics method is also compared to the present and previous test results found in literature and also to other methods for strength analysis including code design methods. The probabilistic fracture mechanics method shows a good ability to predict strength, with the exception of very small beams.
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Experimental and Numerical Investigation on the Shear Strength of Glulam

https://research.thinkwood.com/en/permalink/catalogue2237
Year of Publication
2010
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Crocetti, Roberto
Gustafsson, Per-Johan
Danielsson, Henrik
Emilsson, Arne
Ormarsson, Sigurdur
Organization
Lund University
Technical University of Denmark
Year of Publication
2010
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Keywords
Shear Strength
Shear Loading
Boundary Conditions
Conference
CIB-W18 Meeting
Research Status
Complete
Summary
The general objective of this study is to gain a better knowledge on the shear strength of glulam subjected to predominant shear loading and with different boundary conditions. Specific objectives include the following: - Propose a practical setup for testing glulam in shear which does not generate too large secondary stresses in the specimen, e.g. perpendicular to the grain stresses. - Investigate the shear strength of glulam specimens both with I-cross section and with rectangular cross section. - Investigate the influence of growth ring orientation on the shear strength of glulam.
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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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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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Structural Analysis of In-Plane Loaded CLT Beam with Holes: FE-Analyses and Parameter Studies

https://research.thinkwood.com/en/permalink/catalogue2236
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Beams
Author
Jelec, Mario
Rajcic, Vlatka
Danielsson, Henrik
Serrano, Erik
Organization
University of Osijek
University of Zagreb
Lund University
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Holes
In-Plane Loading
Shear Loading
Numerical Models
FE model
Conference
INTER
Research Status
Complete
Summary
The aim of this paper is to investigate the performance of CLT beams with and without holes loaded in-plane under various loading conditions with special emphasis on shear loading and the in-plane shear behaviour considering the complex internal structure. CLT beams present a much better solution for beams with holes or notches as compared to glued laminated timber beams thanks to its lay-up where tensile forces perpendicular to the beam axis can be transferred by the transversal layers. In order to have in-depth understanding of the local mechanical behaviour in shear stress transfer between laminations, numerical analyses based on 3D-FE models are used.
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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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Shear Capacity of Stud-Groove Connector in Glulam-Concrete Composite Structure

https://research.thinkwood.com/en/permalink/catalogue2217
Year of Publication
2017
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Timber-Concrete Composite
Author
Xie, Lan
He, Guojing
Wang, Alice
Gustafsson, Per-Johan
Crocetti, Roberto
Chen, Liping
Li, Li
Xie, Wenhui
Organization
Central South University of Forestry and Technology
Luleå University of Technology
Lund University
Publisher
North Carolina State University
Year of Publication
2017
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Timber-Concrete Composite
Topic
Connections
Mechanical Properties
Keywords
Stud-Groove Connector
Shear Capacity
Slip Modulus
Johansen's Yield Model
Shear Strength
Research Status
Complete
Series
BioResources
Summary
A timber-concrete composite structure (TCC) is economically and environmentally friendly. One of the key design points of this kind of structure is to ensure the reliability of the shear connectors. The objective of this paper is to study the mechanical property of stud-groove-type connectors and to provide shear capacity equations for stud-groove connectors in timber-concrete composite structures. Based on the Johansen Yield Theory (European Yield Model), some mechanical models and capacity equations for stud-groove-type connectors in timber-concrete structures were studied. Push-out specimens with different parameters (stud diameter, stud length, groove width, and groove depth) were tested to obtain the shear capacity and slip modulus. The experimental strengths were used to validate equations given in the paper. The shear capacity and slip modulus of stud-groove-type connectors was in direct proportion to the diameter of studs and the dimension of the groove. Comparison between the theoretical and the experimental shear strength results showed reasonable agreement. The highlight of this study on shear capacity equations could significantly reduce the push-out tests before investigating the other properties of TCC.
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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
Author
Danielsson, Henrik
Jelec, Mario
Serrano, Erik
Organization
Lund University
Year of Publication
2017
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Strength
Stiffness
In-Plane Loading
Analytical Models
Holes
Notch
Research Status
Complete
Summary
This report concerns element strength and stiffness of cross laminated timber (CLT) at in-plane beam loading and includes presentation of experimental investigations and a review of some analytical models for structural analysis. A total of 20 individual tests were carried out, divided into five different test series which each comprise four nominally equal tests. The test series include prismatic beams (two test series), beams with a hole (two test series) and beams with an end-notch (one test series). All CLT elements were composed of 5 layers of laminations, with three layers of longitudinal laminations of width 40 mm and two layers of transversal laminations of width 20 mm. Test results relating to beam strength are presented in terms of maximum applied load and also in terms of stress components as calculated by analytical models. The review of models for stress analysis reveals significant influence of the element layup and laminations width on the predicted stresses. Test results relating to beam stiffness are present as element shear stiffness and element local and global modulus of elasticity, evaluated based on the European test standard EN 408.
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Experimental Investigation of the Axial Strength of Glued-in Rods in Cross Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue2230
Year of Publication
2018
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Azinovic, Boris
Serrano, Erik
Kramar, Miha
Pazlar, Tomaž
Organization
The Slovenian National Building and Civil Engineering Institute
Lund University
Publisher
Springer Netherlands
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Glued-In Rods
Pull-Pull Tests
Failure Mechanisms
Research Status
Complete
Series
Materials and Structures
Summary
This paper presents results from an experimental assessment of glued-in rods in cross laminated timber (CLT). For the purposes of the study more than 60 pull–pull tests were performed, where the specimens varied in terms of bonded-in length (from 80 to 400 mm), rod diameter (16–24 mm) and rod-to-grain angle (parallel and perpendicular). Several different failure modes that are not common for other applications of glued-in rods (e.g., a failure between CLT layers) were obtained for the analysed CLT specimens. It was found that these failure mechanisms can substantially influence the obtained ultimate tension loads. At the end, the experimental results were compared with empirical and semi-empirical equations for estimating the pull-out strength of glued-in rods in structural timber and glulam. The comparison showed that most of the existing equations overestimate the ultimate tension loads for specimens with the rod parallel to the grain and underestimate the ultimate tension load for specimens with the rod perpendicular to the grain. The results vary because the possible CLT failure modes were not included in previous studies. Further studies are proposed to improve the equations for glued-in rods in CLT.
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Cross Laminated Timber at In-Plane Beam Loading – New Analytical Model Predictions and Relation to EC5

https://research.thinkwood.com/en/permalink/catalogue2232
Year of Publication
2018
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Jelec, Mario
Danielsson, Henrik
Serrano, Erik
Rajcic, Vlatka
Organization
University of Osijek
Lund University
University of Zagreb
Year of Publication
2018
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Failure Mode
Analytical Model
FE Analysis
Shear Failure
Conference
INTER
Research Status
Complete
Summary
The aim of the paper is to present a new model in terms of improvements of the original analytical model by Flaig & Blass (2013). Model improvements as presented by Danielsson & Serrano (2018) are reviewed and further improvements of that model are also presented. The differences between the models concern internal force and stress distributions relevant for shear failure mode III of CLT beams. Predictions of the original and the new analytical models are compared to results of 3D FE-analyses and design proposals based on the new analytical model are presented.
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17 records – page 1 of 2.