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Bending Properties of Cross Laminated Timber (CLT) with a 45° Alternating Layer Configuration

https://research.thinkwood.com/en/permalink/catalogue319
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Buck, Dietrich
Wang, Alice
Hagman, Olle
Gustafsson, Anders
Publisher
North Carolina State University
Year of Publication
2016
Country of Publication
United States
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Bending Test
Norway Spruce
Four Point Bending Test
Alternating Layer
Language
English
Research Status
Complete
Series
BioResources
Summary
Bending tests were conducted with cross laminated timber (CLT) panels made using an alternating layer arrangement. Boards of Norway spruce were used to manufacture five-layer panels on an industrial CLT production line. In total, 20 samples were tested, consisting of two CLT configurations with 10 samples of each type: transverse layers at 45° and the conventional 90° arrangement. Sample dimensions were 95 mm × 590 mm × 2000 mm. The CLT panels were tested by four point bending in the main load-carrying direction in a flatwise panel layup. The results indicated that bending strength increased by 35% for elements assembled with 45° layers in comparison with 90° layers. Improved mechanical load bearing panel properties could lead to a larger span length with less material.
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Moment Resisting Frames and Connections Using Threaded Rods in Beam-to-Column Timber Joints

https://research.thinkwood.com/en/permalink/catalogue2001
Year of Publication
2018
Topic
Design and Systems
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Frames
Wood Building Systems

Performance of Self-Tapping Screws and Threaded Steel Rods in Shear Reinforcement of Glulam Beams

https://research.thinkwood.com/en/permalink/catalogue1628
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Jockwer, Robert
Steiger, René
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Connections
Mechanical Properties
Keywords
Norway Spruce
Reinforcement
Self-Tapping Screws
Threaded Steel Rod
Stiffness
Strength
Load Carrying Capacity
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 2813-2822
Summary
Norway spruce glulam beams with artificial horizontal slits of different length and depth were reinforced using self-tapping screws and threaded steel rods in order to restore their load-carrying capacity and stiffness. The study aimed at evaluating the effects of strength and stiffness of the applied reinforcing elements on the load-carrying capacity and stiffness of glulam beams after retrofitting. Self-tapping screws and threaded steel rods of different diameter have been evaluated in the study and different numbers of reinforcing elements have been applied. Shear failure of the beams with artificial slits of different depth was provoked in loading cycles with stepwise installation of the reinforcing elements in the beam parts failed in the preceding test. The reinforcing effect of the tested self-tapping screws and threaded steel rods reached and partly exceeded the estimated level calculated with selected analytical models. Unfavourable structural behaviour arose in some cases from crack opening during installation of the rods causing a very low initial stiffness. Comparison of test results to calculations of stiffness and load-carrying capacity of the reinforced beams applying the -method, the shear analogy method and a truss model revealed that the -method and the shear analogy method provided the best estimates of strength / stiffness of the reinforced beams.
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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
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.
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