Skip header and navigation

11 records – page 1 of 2.

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
Country of Publication
Austria
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
Language
English
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.
Online Access
Free
Resource Link
Less detail

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
Country of Publication
Austria
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
Language
English
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.
Online Access
Free
Resource Link
Less detail

In Plane Shear Strength of Cross Laminated Timber (CLT): Test Configuration, Quantification and influencing Parameters

https://research.thinkwood.com/en/permalink/catalogue2121
Year of Publication
2013
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems

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
Country of Publication
Germany
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Axial Load
Self-Tapping Screws
Withdrawal
Probabilistic Model
Language
English
Research Status
Complete
Series
European Journal of Wood and Wood Products
ISSN
1436-736X
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.
Online Access
Free
Resource Link
Less detail

Production and Technology of Cross Laminated Timber (CLT): A State-of-the-Art Report

https://research.thinkwood.com/en/permalink/catalogue263
Year of Publication
2013
Topic
General Information
Material
CLT (Cross-Laminated Timber)
Author
Brandner, Reinhard
Year of Publication
2013
Country of Publication
Austria
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
General Information
Keywords
Production
Technology
Language
English
Conference
European Conference on Cross Laminated Timber (CLT)
Research Status
Complete
Notes
May 21-22, 2013, Graz, Austria
Summary
Cross laminated timber (CLT) has been developed to a worldwide well-known and versatile useable building material. Currently increasing rates in production volume and distribution can be observed. In fact CLT, thanks to its laminar structure making it well suited for use in construction, provides new horizons in timber engineering, in areas which had until now been the realm of mineral building materials like concrete and masonry. After a short introduction, this paper aims to demonstrate current production processes used for rigid CLT. In section 2 the process steps are described and essential requirements, as well as pros and cons of various production techniques, are discussed. Latest results of R & D and of development and innovation in production technology are presented. In section 3 test and monitoring procedures in the area of the internal quality assurance, known as factory production control (FPC), are presented. Diverse regulations, in the form of technical approvals for CLT as well as in the CLT product standard prEN 16351 [1], are discussed. Additionally, some technological aspects of the product, CLT, together with a comparison of geometrical and production relevant parameters of current technical approvals in Europe are provided in section 4. In the final and main part of the paper, production and technology is presented in a condensed way. The outlook for current and future developments, as well as the ongoing establishment of the solid construction technique with CLT, is given. The product, CLT, comprises an enormous potential for timber engineering as well as for society as a whole. Standardisation and further innovation in production, prefabrication, joining technique, building physics and building construction make it possible for timber engineering to achieve worldwide success.
Online Access
Free
Resource Link
Less detail

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
Country of Publication
Croatia
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Failure
Rolling shear
Testing
Norway Spruce
Pine
Birch
Beech
Poplar
Ash
Language
English
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.
Online Access
Free
Resource Link
Less detail

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
Country of Publication
Netherlands
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
Language
English
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.
Online Access
Free
Resource Link
Less detail

11 records – page 1 of 2.