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17 records – page 1 of 2.

Approximation of Stresses in Multi-Span CLT Beams Based on Refined Zigzag Theory

https://research.thinkwood.com/en/permalink/catalogue2204
Year of Publication
2019
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Beams

Comparison of Verification and Reinforcement Concepts for Timber Beams with Large Round Holes

https://research.thinkwood.com/en/permalink/catalogue1714
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Dröscher, Julia
Augustin, Manfred
Schickhofer, Gerhard
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Reinforcement
Shear Stresses
Tensile Stresses
Load Carrying Capacity
Numerical Investigation
Analytical Investigation
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 4529-4538
Summary
Within this paper a comparison of different reinforcement concepts for timber beams with round holes is carried out. Therefore currently applied standardized methods and two recently developed approaches are considered. By means of numerical and analytical investigations it becomes apparent that the analysed reinforcement methods divergent to those given in current standards have great potential: shear stresses as well as tensile stresses perpendicular to the grain in the critical areas around the beam opening can be reduced significantly. Hence, the maximum load carrying capacities of the new reinforcement concepts supposedly exceed the standardized ones considerably. For verification of the results experimental investigations on beams with different reinforcement methods are planned.
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Elastic Constants of Cross Laminated Timber Panels of Industrial Size: Non-Destructive Measurement and Verification

https://research.thinkwood.com/en/permalink/catalogue1538
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Zhou, Jianhui
Chui, Ying Hei
Schickhofer, Gerhard
Frappier, Julie
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Elastic Constants
Modulus of Elasticity
Shear Modulus
Non-Destructive Tests
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 1061-1068
Summary
Cross laminated timber (CLT) is leading the evolution of wood construction throughout the world. As atwo-dimensional plate-like construction product, the in-plane elastic constants of CLT panels are the fundamental parameters for serviceability design. The elastic constants including moduli of elasticity (MOE) in major and minor strength direction ( and y) and in-plane shear modulus ( xy) of full-size CLT panels with different dimensions and layups from three CLT producers were measured by a non-destructive test (NDT) method developed by the first author. In total, 51 CLT panels were tested with most of the testing conducted at CLT mills. The measured values were used to examine the existing effective stiffness prediction models of CLT. Results show that k-method can be used for predicting and y values of industrial size CLT with a large length/ width to thickness ratio. xy cannot be well predicted by k-method and is greatly affected by edge bonding and gaps. Gamma method and shear analogy method can include the effect of transverse shear to different extents into account in predicting apparent or y. Shear analogy method appears to predict closer apparent to the measured values than gamma method for CLT with small length to thickness ratio. However, the effect of transverse shear on apparent y is not as much as predicted by shear analogy method for CLT panels with width from 1 to 3 meters. NDT by modal testing was proven to be an efficient mechanical property evaluation method for full-size CLT panels.
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External Thermal Insulation Composite Systems in Solid Timber Construction

https://research.thinkwood.com/en/permalink/catalogue1639
Year of Publication
2016
Topic
Serviceability
Moisture
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Günther, Simon
Ringhofer, Andreas
Schickhofer, Gerhard
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Serviceability
Moisture
Keywords
External Thermal Insulation Composite Systems
Hygrothermal
Long-term
Monitoring
Temperature
Relative Humidity
Moisture Content
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 3169-3178
Summary
External thermal insulation composite systems (ETICS) combined with cross laminated timber (CLT) reveal useful exterior wall constructions, which meet the requirements for sustainability, serviceability and durability of modern buildings efficiently. Associated thermal insulation and moisture protection requirements are essential design criteria to be considered in the planning process. In light of the European legal regulation concerning ETICS, our paper deals with the hygrothermal behavior of an existing exterior wall construction in solid timber construction with ETICS, experimentally determined by means of long-term monitoring situated in the residential project "_massive_living" (Graz, AT). Based on obtained data of temperature and rel. humidity for a period of two years, we not only evaluated building physics aspects concerning the suitability of the structure, but also derived the time depending course of the essential parameter "moisture content" for selected layers of the CLT element. In addition, corresponding data is compared with results gained from a hygrothermal simulation. Further investigation then was carried out determining the hygrical impact on the timber component by changing insulation material. Therefore, the hygrothermal behavior of commonly applied ETICS in combination with CLT as base material was simulated. Finally, resulting bandwidths of moisture content in dependence of the applied ETICS are shown and discussed.
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Finite Element Modelling of the Cyclic Behaviour of CLT Connectors and Walls

https://research.thinkwood.com/en/permalink/catalogue1653
Year of Publication
2016
Topic
Mechanical Properties
Seismic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Aranha, Chrysl
Branco, Jorge
Lourenço, Paulo
Flatscher, Georg
Schickhofer, Gerhard
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Mechanical Properties
Seismic
Connections
Keywords
Shear Tests
Axial Tests
Cyclic Loads
Force-Displacement Curves
Numerical Model
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 3533-3540
Summary
The characterization of the behaviour of connectors used in Cross-laminated Timber (CLT) structures is an important aspect that needs to be considered in their seismic design. In this paper, the data from shear and axial tests conducted on connectors have been used to define their force-displacement curves under cyclic loads using the SAWS model in OpenSees. The component curves were then incorporated into the corresponding wall models and the results were compared with their experimental counterparts, in order to determine the validity of the finite element model. Thereby, the non-linear behaviour was restricted to the connectors while the walls themselves were composed of linear orthotropic shell elements. The models were found to provide a good estimate of the initial stiffness and maximum load capacity of the wall specimens. The effects of vertical loading and the presence of openings were determined based on analyses run on the calibrated model.
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Influence of Moisture Content and Gaps on the Withdrawal Resistance of Self Tapping Screws in CLT

https://research.thinkwood.com/en/permalink/catalogue299
Year of Publication
2014
Topic
Connections
Mechanical Properties
Moisture
Material
CLT (Cross-Laminated Timber)
Author
Silva, Catarina
Ringhofer, Andreas
Branco, Jorge
Lourenço, Paulo
Schickhofer, Gerhard
Organization
National Congress of Experimental Mechanics
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Mechanical Properties
Moisture
Keywords
Self-Tapping Screws
Withdrawal
Gaps
Moisture Content
Conference
9th National Congress of Experimental Mechanics
Research Status
Complete
Notes
October 15-17, 2014, Aveiro, Portugal
Summary
Self-tapping screws (STS) have been proclaimed as the easiest solution for structural timber connections, in special for cross laminated timber (CLT) constructions. In order to understand deeply the composite model “CLT-STS”, an experimental campaign which comprised 270 withdrawal tests was carried out. Maximum withdrawal load capacity of self-tapping screws inserted in plane side of a three layered CLT panel was evaluated considering three main parameters: moisture levels of CLT (i), number of gaps (ii) and the width of gaps (iii). Regarding (i), connections were tested with CLT at 8%, 12% and 18% of moisture content. Concerning (ii) and (iii), different test configurations with 1, 2 and 3 gaps, with 0 or 4mm, were tested. The influences of moisture content and number of gaps were modeled. Further a correlation between test results and a prediction model developed by Uibel and Blaß (2007) has been proposed.
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The Influences of Moisture Content Variation, Number and Width of Gaps on the Withdrawal Resistance of Self Tapping Screws inserted in Cross Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1359
Year of Publication
2016
Topic
Connections
Moisture
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Silva, Catarina
Branco, Jorge
Ringhofer, Andreas
Lourenço, Paulo
Schickhofer, Gerhard
Publisher
ScienceDirect
Year of Publication
2016
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Connections
Moisture
Mechanical Properties
Keywords
Withdrawal Tests
Withdrawal Resistance
Self-Tapping Screws
Moisture Content
Gaps
Research Status
Complete
Series
Construction and Building Materials
Summary
A large experimental campaign comprised of 470 withdrawal tests was carried out, aiming to quantify the withdrawal resistance of self-tapping screws (STS) inserted in the side face of cross laminated timber (CLT) elements. In order to deeply understand the “CLT-STS” composite model, the experimental tests considered two main parameters: (i) simple and cyclic changes on moisture content (MC) and (ii) number and width of gaps. Regarding (i), three individual groups of test specimens were stabilized with 8%, 12% and 18% of moisture content and one group was submitted to a six month RH cycle (between 30% and 90% RH). Concerning (ii), different test configurations with 0 (REF), 1, 2 and 3 gaps, and widths equal to 0mm (GAP0) or 4mm (GAP4), were tested. The influences of MC and number of gaps were modeled by means of least square method. Moreover, a revision of a prediction model developed by Uibel and Blaß (2007) was proposed. The main findings of the experimental campaign were: the decrease of withdrawal resistance for specimens tested with MC=18% in most configurations; the unexpected increase of withdrawal resistance as the number of gaps with 0mm increased; and, the surprising increase of withdrawal resistance for REF specimens submitted to the RH cycle.
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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
Author
Brandner, Reinhard
Bogensberger, Thomas
Schickhofer, Gerhard
Organization
Graz University of Technology
Year of Publication
2013
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Keywords
Shear Resistance
Shear Loads
In-Plane Shear Strength
Single Nodes
Net-Shear
Conference
International Council for Research and Innovation in Building and Construction, Working Commission W18 - Timber Structures
Research Status
Complete
Summary
Cross laminated timber (CLT) has become a well-known and widely applied two-dimensional, engineered timber product worldwide. It constitutes a rigid composite of an odd number of orthogonal and glued layers. Focusing on a single glued node loaded in plane in shear and composed of two crossed board segments and the adhesive layer in-between, in principle three types of shear mechanisms can be distinguished: mechanism I "net-shear" (shearing perpendicular to grain), mechanism II "torsion" and mechanism III "gross-shear" (shearing parallel to grain). In fact, while having generally accepted values for the resistance against mechanism II and good estimates for mechanism III the resistance against "net-shear" (mechanism I) is still in discussion. In spite of numerous investigations on nodes and on whole CLT elements in the past, a common sense concerning the test procedure, the consideration and handling of distinct influencing parameters and the quantification of the shear strength are open. We focus on the in plane shear resistance of single nodes according to mechanism I. We (i) propose a test configuration for reliable determination of the shear strength, (ii) determine the shear resistance in case of shear loads perpendicular to grain, (iii) discuss influences of some parameters on the shear strength of single nodes, and (iv) give a brief outlook concerning the resistance of CLT elements against shear loads in plane.
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Mechanical Properties of Glued Laminated Timber and Cross Laminated Timber Produced with the Wood Species Birch

https://research.thinkwood.com/en/permalink/catalogue1523
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Author
Jeitler, Georg
Augustin, Manfred
Schickhofer, Gerhard
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Keywords
Production
Birch
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 640-647
Summary
Is a wood processing company with about 1,000 employees andplants in Austria, Slovenia and Russia. In the forest around their Russian sawmill “HasslacherLes” the wood species birch (Betula pendula) is growing in large quantities and cut-able qualities. The company has also very modern equipment for the production of glued laminated and cross laminated timber. Consequently the idea was born to develop a project to produce load-carrying members to check the possibility of production of glued laminated timber and cross laminated timber without large modification of the existing production process. The goal of the project was to set up a complete profile of the mechanical properties needed for the design according to EN 1995-1-1. In addition by the means of a pilot project (detached house) erected with birch Cross Laminated Timber the effectiveness of this product for structural purposes with slender wooden components could be shown. The second pilot project was an industrial hall made of Glued Laminated Timber with birch.
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Multi-Storey Residential Buildings in CLT - Interdisciplinary Principles of Design and Construction

https://research.thinkwood.com/en/permalink/catalogue500
Year of Publication
2014
Topic
Serviceability
Moisture
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Ringhofer, Andreas
Schickhofer, Gerhard
Year of Publication
2014
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Serviceability
Moisture
Design and Systems
Keywords
Moisture Ingress
Critical Building Zones
Efficiency of Construction
Multi-Storey
Residential
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Cross-laminated timber (CLT) is a very efficient and powerful building material and thus recently discovered for the erection of multi-storey timber towers. In our paper, we focus on building science and services related topics regarding these constructions. Thereby, we firstly identify moisture ingress as main problem worsening their durability and thus discuss possible detail solutions for both external and internal critical building zones such as flat roof, balcony system and wet rooms. The second main topic we are concentrating in this paper are simple measures to increase the efficiency of CLT constructions by simplifying and improving their structural systems (floors, walls and connections). Both topics are connected by the major importance of interdisciplinary thinking and acting when building with CLT.
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17 records – page 1 of 2.