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Out-of-Plane Tensile Properties of Cross Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue2940
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Brandner, Reinhard
Jantscher, Lukas
Organization
Graz University of Technology
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Keywords
Out-Of-Plane Tension
Size Effect
System Effects
Modulus of Elasticity
Strength
Equicorrelation
Research Status
Complete
Series
Buildings
Summary
A systematic investigation is still lacking for tension out-of-plane in cross laminated timber (CLT), as a planar timber construction product. The objectives of the present study are the determination of the tensile properties of CLT made of Norway spruce, the identification of essential product-specific influencing parameters and a comparative analysis with glulam. For this purpose, seven test series were defined, which allowed the determination of the tensile properties on board segments and thereof produced glulam and CLT specimens by varying the number of layers, layer orientation and number of elements within a layer. The orthogonal laminated structure of CLT led to between 50% and 70% higher tensile properties out-of-plane, which is explained by the different stress distribution compared to glulam; the regulation of 30% higher properties than for glulam is suggested. In addition, the lognormal distribution turned out to be a more representative distribution model for characterizing the tensile strength out-of-plane than the Weibull distribution. This was also confirmed with regard to the investigated serial and parallel system effects, in which a clearly more homogeneous behavior was found in CLT compared to glulam, which in turn can be attributed again to the different stress distributions.
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Design of Connections in Timber Structures

https://research.thinkwood.com/en/permalink/catalogue1937
Year of Publication
2018
Topic
Connections
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Bader, Thomas
Blaß, Hans Joachim
Bocquet, Jean-François
Branco, Jorge
Brandner, Reinhard
Manuel Cabrero, José
de Proft, Kurt
Descamps, Thierry
Dietsch, Philipp
Franke, Bettina
Franke, Steffen
Görlacher, Rainer
Jockwer, Robert
Jorissen, André
Kleiber, Marion
Lemaître, Romain
Munch-Andersen, Jørgen
Pazlar, Tomaž
Ranasinghe, Keerthi
Ringhofer, Andreas
Sandhaas, Carmen
Schweigler, Michael
Stepinac, Mislav
Tuhkanen, Eero
Verbist, Maxime
Yurrita, Miguel
Editor
Sandhaas, Carmen
Munch-Andersen, Jørgen
Dietsch, Philipp
Publisher
COST (European Cooperation in Science and Technology)
Year of Publication
2018
Format
Book/Guide
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Design and Systems
Keywords
Eurocode 5
Fasteners
Screws
Dowel Type Fastener
Glued-In Rods
Numerical Modeling
Europe
Load Distribution
Research Status
Complete
Summary
This state-of-the-art report has been prepared within COST Action FP1402 Basis of structural timber design from research to standards, Working Group 3 Connections. The Action was established to create an expert network that is able to develop and establish the specific information needed for standardization committee decisions. Its main objective is to overcome the gap between broadly available scientific results and the specific information needed by standardization committees. This necessitates an expert network that links practice with research, i.e. technological developments with scientific background. COST presents the ideal basis to foster this type of joint effort. Chapter 8 Connections presents an integral part of Eurocode 5 and is in need of revision. This state-of-the-art report shall provide code writers with background information necessary for the development of the so-called Second Generation of the Eurocodes, now aimed to be produced in 2022.
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Properties, Testing and Design of Cross Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1938
Year of Publication
2018
Topic
Design and Systems
Mechanical Properties
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Abeysekera, Ishan
Bezzi, Stefano
Bidakov, Andrii
Björnfot, Anders
Bogensperger, Thomas
Brandner, Reinhard
Casagrande, Daniele
Ehrhart, Thomas
Fiorencis, Mariano
Follesa, Maurizio
Lawrence, Andrew
Lukacs, Ildiko
Moosbrugger, Thomas
Niebuhr, Peter
Pasca, Dag
Pradel, Claudio
Schickhofer, Gerhard
Serrano, Erik
Shotton, Elizabeth
Sieder, Mike
Sigrist, Christophe
Silly, Gregor
Smith, Andrew
Stojmanovska, Marta
Tomasi, Roberto
Tsipiras, Vasileios
Wiegand, Tobias
Editor
Brandner, Reinhard
Tomasi, Roberto
Moosbrugger, Thomas
Serrano, Erik
Dietsch, Philipp
Publisher
COST (European Cooperation in Science and Technology)
Year of Publication
2018
Format
Book/Guide
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Design and Systems
Mechanical Properties
Seismic
Keywords
Fatigue
Bending
Shear
Compression
Rolling Shear
Research Status
Complete
Summary
The intention of this STAR is a more detailed summary of the relevant work, done during the last 20 years on the topic of CLT. Additional references not included in the documents of SC5.T1 were added highlighting also CLT relevant publications not directly addressing content of the CLT draft version for EC 5. Apart from providing additional references for all topics and chapters of SC5.T1 draft documents edited by WG 2 / TG 1 & TG 3 within this STAR, further necessary scoentific work was identified and listed.
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Basis of Design Principles for Timber Structures

https://research.thinkwood.com/en/permalink/catalogue1939
Year of Publication
2018
Topic
Serviceability
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Abeysekera, Ishan
Baravalle, Michele
Brandner, Reinhard
Colling, François
Fink, Gerhard
Hamm, Patricia
Hochreiner, Georg
Honfi, Dániel
Ilharco, Tiago
Jockwer, Robert
Kleinhenz, Miriam
Kohler, Jochen
Lawrence, Andrew
Marcroft, Julian
Mikoschek, Michael
Toratti, Tomi
Editor
Fink, Gerhard
Honfi, Dániel
Kohler, Jochen
Dietsch, Philipp
Publisher
COST (European Cooperation in Science and Technology)
Year of Publication
2018
Format
Book/Guide
Material
CLT (Cross-Laminated Timber)
Topic
Serviceability
Design and Systems
Keywords
Eurocode
Deflection
Vibrations
Serviceability Limit States
Eurocode 5
Dowel Type Fastener
Failure Behavior
Research Status
Complete
Summary
This report represents the results of the activities performed in working group 1, Basis of Design. The most important task of working group 1 was the defragmentation and harmonization of techniques and methods that are necessary to prove the reliable, safe and economic application of timber materials or products in the construction industry. This report is structured into five parts. At first general principles regarding the design formats are addressed (Part I). Afterwords timber specific aspects regarding code calibration (Part II) and serviceability (Part III) are summarized. In Part IV other demanding issues for the implementation into Eurocode 5 are addressed. Here also summaries of joint activities with other working groups on cross laminated timber and timber connections are presented. The report concludes with a guideline for data analysis (Part V).
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Probabilistic Models for the Withdrawal Behavior of Single Self-Tapping Screws in the Narrow Face of Cross Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue1388
Year of Publication
2018
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Brandner, Reinhard
Ringhofer, Andreas
Grabner, Martin
Publisher
Springer Berlin Heidelberg
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Axial Load
Self-Tapping Screws
Withdrawal
Probabilistic Model
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
Cross laminated timber (CLT) and self-tapping screws have strongly dominated the latest developments in timber engineering. Although knowledge of connection techniques in traditional light-frame structures can be applied to solid timber constructions with CLT, there are some product specifics requiring additional attention; for example in positioning of fasteners, differentiation in the side face and narrow face of the panels and the influence of potential gaps. The load–displacement behaviour of single, axially-loaded self-tapping screws positioned in the narrow face of CLT and failing in withdrawal was investigated. For the first time a multivariate probabilistic model was formulated together with models relating the parameters with the thread-fibre angle and the density. Different types and widths of gaps, initial slip and / or delayed stiffening as well as softening after exceeding of the maximum load can be considered. Beyond the scope of this contribution, the probabilistic model is seen as a worthwhile basis for investigations into the withdrawal behaviour of primary axially loaded, compact groups of screws positioned in timber products and subjected to withdrawal failure.
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Group Action of Axially-Loaded Screws in the Narrow Face of Cross Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1496
Year of Publication
2016
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Author
Brandner, Reinhard
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Connections
Keywords
Axially-Loaded
Self-Tapping Screws
Withdrawal Properties
Stochastic Approach
Load-Displacement Curves
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 209-218
Summary
Withdrawal properties of axially-loaded groups of screws in the narrow face of cross laminated timber (CLT) are investigated by means of a stochastic approach based on a single screw model which provides a complete stochastic description of the load-displacement curve. Different group dimensions and configurations are analysed, featuring screws with equal or different thread-fibre angles. The stochastic approach is successfully verified by tests. Influences caused by shortcomings in assembling and by screws penetrating knots as well as gaps are addressed. Suggestions, relevant for the development of CLT system connectors and for practical applications, are made.
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Block Shear Failure Mode of Axially Loaded Groups of Screws

https://research.thinkwood.com/en/permalink/catalogue1512
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Solid-sawn Heavy Timber
Author
Mahlknecht, Ursula
Brandner, Reinhard
Augustin, Manfred
Year of Publication
2016
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Solid-sawn Heavy Timber
Topic
Connections
Mechanical Properties
Keywords
Self-Tapping Screws
Block Shear Model
Stiffness
Strength
Bending Stresses
Axially-Loaded
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 362-371
Summary
Self-tapping screws are efficient and flexible fasteners, applicable for many types of connections. Investigations on axially loaded groups of screws pointed out, that small spacing between the screws lead to block shear failure mode. So far, block and plug shear failure mode are only analysed for laterally loaded fasteners. Corresponding models cannot be simple transferred to primary axially loaded screws, because of their load insertion continuously along the effective thread featuring a thread-fibre angle perpendicular or with an angle to grain. Results gained by means of two different test configurations, with constant 90° thread-fibre angle but different configurations of group of screws and support conditions are presented. A block shear model is presented, and for mean values for stiffness and strength properties as model parameters are discussed together with values for parameters related to the force distribution over the effective thread length for the first test configuration. Agreement between model and test results was found on a conservative basis. As outlook, considerations of additional bending stresses as well as parameter optimisation are seen as prerequisites and next steps for further model improvement and practicality.
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Rolling Shear Properties of Some European Timber Species with Focus on Cross Laminated Timber (CLT): Test Configuration and Parameter Study

https://research.thinkwood.com/en/permalink/catalogue25
Year of Publication
2015
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Frangi, Andrea
Schickhofer, Gerhard
Brandner, Reinhard
Ehrhart, Thomas
Organization
International Network on Timber Engineering Research (INTER)
Year of Publication
2015
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Failure
Rolling shear
Testing
Norway Spruce
Pine
Birch
Beech
Poplar
Ash
Conference
INTER 2015
Research Status
Complete
Notes
August 24-27, 2015, Šibenik, Croatia
Summary
Cross laminated timber (CLT) has gained popularity and relevance in the construction industry during the past decade. Its versatile applicability, economic competitiveness as well as an increasing social consciousness for sustainable constructions have been main reasons for this positive development. Its laminar composition enables CLT to withstand in- and out-of-plane loads. Due to its structure featuring orthogonally oriented adjacent layers, in CLT loaded out-of-plane, shear and more specific rolling shear has to be considered in ultimate (ULS) as well as serviceability limit state (SLS) design. This is because rolling shear constitutes a potential failure mechanism and contributes a noticeable amount to the overall deflection. Comprehensive knowledge on rolling shear modulus (GR) and strength (fR) is therefore of utmost importance for an adequate design of CLT structures. Previous investigations on rolling shear properties and their influential parameters have primarily been performed numerically and using Norway spruce (Picea abies). The main goal of our contribution, based on investigations detailed in Ehrhart (2014), was to identify the most important parameters for rolling shear characteristics and to quantify their influence. Furthermore, information about the rolling shear performance of several timber species was analysed to investigate their potential for use in CLT-products. In view of upcoming new timber species increasingly pushed into the market, investigations on rolling shear comprised also some hardwood and other softwood species with a potential to be used for (cross) laminated timber products.
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Shear Properties of Cross Laminated Timber (CLT) under In-Plane Load: Test Configuration and Experimental Study

https://research.thinkwood.com/en/permalink/catalogue180
Year of Publication
2015
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Brandner, Reinhard
Dietsch, Philipp
Dröscher, Julia
Schulte-Wrede, Michael
Kreuzinger, Heinrich
Sieder, Mike
Schickhofer, Gerhard
Winter, Stefan
Organization
International Network on Timber Engineering Research (INTER)
Year of Publication
2015
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Diaphragms
Failure Mechanisms
Shear Strength
In-Plane Shear Test
Conference
INTER 2015
Research Status
Complete
Notes
August 24-27, 2015, Sibenik, Croatia
Summary
Consolidated knowledge of CLT properties under in-plane shear is crucial for typical structural applications such as wall and floor diaphragms, cantilevered CLT walls and CLT used as (deep) beams, in all cases potentially featuring holes or notches. The current technical approvals for CLT products contain differing regulations to determine their load-carrying capacities in-plane. Generally they imply a verification of the torsional stresses in the cross-section of the cross-wise glued elements as well as a verification of the shear stresses proportionally assigned to the boards of the top and cross layers. The basis of theoretical and practical considerations are the following three basic failure scenarios for a CLT-element under in-plane shear: (i) gross-shear (longitudinal shearing in all layers), (ii) net-shear (transverse shearing in all layers in weak direction), and (iii) torsion failure in the gluing interfaces between the layers.
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Self-Tapping Screws and Threaded Rods as Reinforcement for Structural Timber Elements - A State-Of-The-Art Report

https://research.thinkwood.com/en/permalink/catalogue448
Year of Publication
2015
Topic
Connections
Serviceability
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Author
Dietsch, Philipp
Brandner, Reinhard
Publisher
ScienceDirect
Year of Publication
2015
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Topic
Connections
Serviceability
Keywords
Reinforcement
Threaded Rods
Self-Tapping Screws
Shear Stress
Europe
Research Status
Complete
Series
Construction and Building Materials
Summary
In timber engineering, self-tapping screws, optimized primarily for axial loading, represent the state-of-the-art in fastener and reinforcement technology. Their economic advantages and comparatively easy handling make them one of the first choices for application in both domains. This paper focuses on self-tapping screws and threaded rods applied as reinforcement, illustrating the state-of-the-art in application and design approaches in Europe, in conjunction with numerous references for background information. With regard to medium to large span timber structures which are predominately erected by using linear timber members, from e.g. glued laminated timber, the focus of this paper is on their reinforcement against stresses perpendicular to grain as well as shear. However, latest findings with respect to cross laminated timber are included as well.
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12 records – page 1 of 2.