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Effect of Holes on the Structural Capacities of Laminated Veneer Lumber

https://research.thinkwood.com/en/permalink/catalogue2045
Year of Publication
2018
Topic
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Author
Yeh, Borjen
Herzog, Benjamin
Year of Publication
2018
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Topic
Mechanical Properties
Keywords
Holes
Bending Moment
Shear
Bending Stiffness
Bending Tests
Shear Tests
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
Laminated veneer lumber (LVL) is an engineered wood product manufactured from specially selected veneers with varying strength and stiffness properties. LVL products are often specified where a certain span, strength and/or stiffness is required. As such, LVL products are generally designed for and used in applications where they will be highly stressed under design loads. For this reason, field modifications, such as notching, tapering, or drilling should be avoided and never done without a thorough understanding of the effects on the structural capacities of the LVL. Nonetheless, it is not uncommon for the designer and contractor to find a need to cut holes through LVL members for plumbing pipes, electrical conduits, or air ducts. Therefore, it is usually necessary to determine the residual structural capacities of the LVL member when holes are cut. The objective of this paper is to examine the effect of round holes on the structural capacities of LVL, including bending moment, shear, and bending stiffness. Full-scale LVL bending and shear tests were conducted to provide data for characterization of the hole effect. Based on the test data, design equations that account for single and multiple holes up to 2/3 of the LVL member depth and a clear distance of 15% or more of the LVL depth from the edge of the hole to either tension and compression edge of the LVL member have been developed. To ensure safe implementation of such design recommendations in practice, prescriptive limitations, such as the minimum clear distance between the face of a support and the edge of a hole, and the minimum clear distance between adjacent holes, are also prescribed.
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Effect of Round Holes in High Shear Zones of Laminated Veneer Lumber

https://research.thinkwood.com/en/permalink/catalogue541
Year of Publication
2014
Topic
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Author
Clouston, Peggi
Meidani, Mehrashk
Year of Publication
2014
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Application
Beams
Topic
Mechanical Properties
Keywords
Finite Element Model
Holes
High Shear Zones
Tsai-Wu Strength Theory
Stress Distributions
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
The purpose of this study was to experimentally and numerically explore the effect of drilled holes in high shear zones of Laminated Veneer Lumber (LVL) beams. A total of 15 full-size shear beam tests were performed on nominal 2x10 1.9E Eastern Species LVL specimens with a span of 1829mm. Three different hole diameters were investigated: 44mm, 70mm, and 92mm drilled at quarter span and mid-depth of the beams. A finite element analysis, coupled with the Tsai-Wu strength theory, was carried out on the same beam configurations to investigate the stress distribution around the holes. It was clear from the stress contour maps that the holes disturb the flow of normal and shear stresses in such a way as to develop significant tensile stresses perpendicular to the grain at specific locations around the hole periphery. The transverse tensile stresses lead to relatively consistent failure loads for the LVL due to the lack of cross plies.
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Holes in Glulam – Orientation and Design of Internal Reinforcements

https://research.thinkwood.com/en/permalink/catalogue1704
Year of Publication
2016
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Author
Tapia, Cristóbal
Aicher, Simon
Year of Publication
2016
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Topic
Mechanical Properties
Keywords
Holes
Steel Rods
Reinforcement
Tensile Stresses
Shear Stresses
Eurocode 5
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 4404-4411
Summary
The usage of holes in glulam and LVL beams is a common practice in timber constructions and requires in many cases the application of reinforcement. At present, Eurocode 5 does not contain design rules for holes, nor for their reinforcement, which are, however, regulated in the German National Annex to EC5. Although it has been proven that internal rod-like reinforcements improve the shear force capacity of a beam with holes, several problems still remain, particularly the inability to successfully reduce peak stresses at the periphery of the hole, especially shear stresses. Inclined internal steel rod reinforcements were studied and compared with vertically oriented rods, which is currently the only regulated application. The analysis revealed a reduction of both perpendicular to grain tensile stresses and shear stresses, which for the case of vertical rods are not reduced at all. A first attempt at the design of such inclined reinforcements was made by deriving an equation based on the results from FEM simulations. The design approach was then applied to an example case. Experimental verification of the theoretical observations is still necessary and ongoing, though a very promising approach for an improved internal reinforcement and its respective design can already be observed.
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Novel Internally LVL-Reinforced Glued Laminated Timber Beams with Large Holes

https://research.thinkwood.com/en/permalink/catalogue1303
Year of Publication
2018
Topic
Design and Systems
Mechanical Properties
Material
LVL (Laminated Veneer Lumber)
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Aicher, Simon
Tapia, Cristóbal
Publisher
ScienceDirect
Year of Publication
2018
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Design and Systems
Mechanical Properties
Keywords
Holes
Reinforcement
Beech
Load Capacity
Research Status
Complete
Series
Construction and Building Materials
Summary
A novel timber composite is presented, consisting of glued laminated timber (GLT) from softwoods and intercalated cross-layered plates of laminated veneer lumber (LVL) made of hardwood species, specifically beech. The structure is especially suited for beams with multiple, large rectangular holes, where the LVL acts as a highly efficient internal reinforcement and contributes to a damage-tolerant ultimate load behavior. The load capacity of the composite beam is not induced by the stress concentrations at the corners of the hole, which, in contrast to generic GLT, lead to a sudden propagation of cracks and brittle failure. It is shown that the structure, including the holes, can be designed analytically in a transparent manner by using beam theory, a parallel system approach, and modifications from FEM analysis for the verification of tensile forces at the hole periphery. The composite, firstly used in a recent multi-story building in Australia, significantly improves the competitiveness of timber in building works, which have been limited to steel and reinforced concrete structures.
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Reinforcement of Round Holes in Glulam Beams Arranged Eccentrically or in Groups

https://research.thinkwood.com/en/permalink/catalogue1627
Year of Publication
2016
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Danzer, Martin
Dietsch, Philipp
Winter, Stefan
Year of Publication
2016
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Holes
Self-Tapping Screws
Load Bearing Capacity
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 2804-2812
Summary
Experimental and numerical investigations on round holes in glulam beams are presented. These were conducted in order to extend the field of practical application, to study the structural behaviour of holes arranged eccentrically or in groups and to generate basic results for deriving a design format. Within these investigations the influence of parameters like eccentricity, clear distance between holes or effect of reinforcement by fully threaded selftapping screws was considered. A comparison of estimated load-bearing capacities on the basis of the Weibull theory and test results shows good agreement. Strain gauge measurements in reinforcing elements confirm the validity of the chosen methods.
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Rod-Shaped Components Made of Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1174
Year of Publication
2012
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Beams
Author
Flaig, Marcus
Blaß, Hans Joachim
Organization
Karlsruher Institut für Technologie
Publisher
KIT Scientific Publishing
Year of Publication
2012
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Load-Bearing Behavior
Notches
Holes
Research Status
Complete
Summary
Brettsperrholz (CLT) besitzt im Gegensatz zu Brettschichtholz verhältnismäßig hohe Schub- und Querzugfestigkeiten. Bauteile aus CLT sind daher weniger empfindlich gegenüber Rissen und weisen eine größere Robustheit auf. Im Rahmen eines Forschungsvorhabens wurde das Tragverhalten von CLT-Trägern mit Ausklinkungen, Durchbrüchen und Queranschlüssen sowie Trägern mit schräg zur Faserrichtung angeschnittenen Rändern untersucht und Bemessungsansätze für die verschiedenen Trägerformen entwickelt.
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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

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

9 records – page 1 of 1.