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10 records – page 1 of 1.

Impact of Cracks to the Hygrothermal Properties of CLT Water Vapour Resistance and Air Permeability

https://research.thinkwood.com/en/permalink/catalogue1326
Year of Publication
2017
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Kukk, Villu
Horta, R.
Püssa, M.
Luciani, G.
Kallakas, Heikko
Kalamees, Targo
Kers, Jaan
Publisher
ScienceDirect
Year of Publication
2017
Country of Publication
Netherlands
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Crack Propagation
Crack Formation
Moisture Content
Water Vapour Transmission
Air Permeability
Language
English
Research Status
Complete
Series
Energy Procedia
Summary
Current research is focused on crack formation and propagation in cross laminated timber (CLT) panels and its impacts on the water vapour resistance and air permeability of panels. Crack formation was examined by means of climate tests with five layer CLT-panels with a thickness of 95 mm. Results of climate tests showed that decreasing the moisture content (MC) from 11 % to 7 % caused mean crack widths in panels of 0.27 mm and 0.38 mm, and an MC decreasing from 17 % to 7 % caused mean crack widths of 0.89 mm and 2.0 mm. From these test results it was concluded that in CLT panels which were produced and stored in a humid environment there was an approximate 200% increase in the mean maximum width of cracks compared to panels stored in a dry environment. The water vapour transmission increased by about 9 % with smaller cracks (that were imitated with 2 mm holes) and 30 % with larger cracks (6 mm holes). The air permeability of CLT at a maximum air pressure difference of 550 Pa was 2.25 l/(s*m2) with 2 mm holes and 5.56 l/(s*m2) with 6 mm holes. It can be concluded from the afore mentioned test results that cracks significantly influence the hygrothermal properties of CLT. Deeper investigation as to the reasons, formation and propagation procedures are needed to avoid inadvisable cracks in CLT.
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Bending Resistance and Deformation Capacity of Fibre Reinforced Glulam Beams

https://research.thinkwood.com/en/permalink/catalogue2208
Year of Publication
2018
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Blank, Lukas
Organization
ETH Zurich
Year of Publication
2018
Country of Publication
Switzerland
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Bending Resistance
Deformation Capacity
Ultimate Load
Fibre Reinforcement
Language
English
Research Status
Complete
Series
IBK Bericht
Online Access
Free
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Compressive Behavior of Glulam Columns with Initial Cracks Under Eccentric Loads

https://research.thinkwood.com/en/permalink/catalogue1463
Year of Publication
2018
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Columns
Author
Zhang, Jing
He, Minjuan
Li, Zheng
Publisher
Springer Berlin Heidelberg
Year of Publication
2018
Country of Publication
Germany
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Columns
Topic
Mechanical Properties
Keywords
Cracks
Compression Loads
Failure Modes
Load Bearing Capacity
Numerical Model
Language
English
Research Status
Complete
Series
International Journal of Advanced Structural Engineering
ISSN
2008-6695
Summary
This paper investigates the mechanical performance of longitudinally cracked glulam columns under eccentric compression loads. Experimental investigation was conducted to explore the influence of initial cracks on the failure modes and load bearing capacity of glulam columns. Two different crack patterns named DC and IC, and two column lengths (i.e. 600 and 1100 mm) were considered in the experiments. It was indicated that these two crack patterns reduced the capacity of slender glulam columns and the difference of failure modes was observed between glulam columns with and without initial cracks. Further, a numerical model was developed and validated by the test results. With the application of cohesive zone material model, the propagation of initial cracks could be considered in the numerical modeling. A parametric study was carried out by the verified model and the influence of crack lengths and crack locations was further investigated. From the numerical analysis, it was found that through cracks reduced the capacity of glulam columns significantly. Also, crack location impacts the capacity of glulam columns and the extent of impact relates to the slenderness ratio of the columns, while cracks with different lengths have similar influence on the capacity of columns.
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Numerical Analysis on Tensile Performance of Bolted Glulam Joints with Initial Local Cracks

https://research.thinkwood.com/en/permalink/catalogue1380
Year of Publication
2018
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Zhang, Jing
He, Minjuan
Li, Zheng
Publisher
Springer Japan
Year of Publication
2018
Country of Publication
Japan
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Keywords
Bolted Joints
Cracks
Finite Element Model
Failure Modes
Tension Load
Language
English
Research Status
Complete
Series
Journal of Wood Science
ISSN
1611-4663
Summary
Under varying climate conditions, cracks are commonly observed in bolted joints, owing to the shrinkage of wood and confinement from slotted-in steel plates and bolts. A three-dimensional finite element model was developed to investigate the mechanical behavior of bolted glulam joints with initial cracks. Wood foundation was prescribed in the model to simulate the local crushing behavior of wood surrounding the bolts. The behavior of wood in compression and the foundation were defined as transversely isotropic plastic in the software package ANSYS. Cohesive zone model was applied in the numerical analysis to consider the propagation of initial cracks and brittle failure of wood in the bolted joints under tension load. The numerical model was validated by the experiments conducted on full-scale specimens and it is indicated that the numerical model has good ability in predicting the failure modes and capacity of tension joints with local cracks. To further investigate the influence of crack number, length and locations, a parametric study was conducted with the verified model. Moreover, to study the effects of cracks on the behavior of bolted joints with different failure modes, another bolted joint including bolts with different strength grades and diameters was designed and analyzed in the parametric study, which was expected to have bolt yielding failure mode. It was found that the initial cracks can decrease the capacity and initial stiffness of tension joints by up to 16.5 and 34.8%, respectively.
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Experimental Investigation of Cracked End-notched Glulam Beams Repaired with GFRP Bars

https://research.thinkwood.com/en/permalink/catalogue2444
Year of Publication
2019
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams

Experiments with Tension and Shear Reinforced Glulam Beams

https://research.thinkwood.com/en/permalink/catalogue2209
Year of Publication
2018
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Blank, Lukas
Frangi, Andrea
Organization
ETH Zurich
Year of Publication
2018
Country of Publication
Switzerland
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Fibre Reinforcement
Bending Resistance
Load Bearing Capacity
Language
English
Research Status
Complete
Series
IBK Bericht
Online Access
Free
Resource Link
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Investigation on Elements Presenting Cracks in Timber Structures

https://research.thinkwood.com/en/permalink/catalogue477
Year of Publication
2014
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Franke, Steffen
Magnière, Noëlie
Year of Publication
2014
Country of Publication
Canada
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Keywords
Cracks
Numerical Model
Stiffness
Load Carrying Capacity
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 10-14, 2014, Quebec City, Canada
Summary
Cracks in timber members influence the stiffness and load-carrying behaviour but only rudimentary rules are given to evaluate cracked members. Therefore, an investigation to gather information about the most frequent characteristics of cracked timber structures has been carried out. This investigation provides the main characteristics of both the timber elements and the crack distributions encountered. These main characteristics have then been used to define a numerical model in order to investigate the impact of cracks on the stiffness and load-carrying capacity of timber beams. Based on these results, the existing rules considering cracks in timber beams can be evaluated and new rules can be developed.
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Load Carrying Capacity of Cracked Beams

https://research.thinkwood.com/en/permalink/catalogue1544
Year of Publication
2016
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Franke, Steffen
Franke, Bettina
Magnière, Noëlie
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
Glulam (Glue-Laminated Timber)
Topic
Mechanical Properties
Keywords
Cracks
Stiffness
Modulus of Elasticity
Load Carrying Capacity
Numerical Investigations
Experimental Investigations
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 1123-1130
Summary
The increasing number of wood structure amongst large and potentially public buildings gave a new impulse to the assessment of timber structures. For assessing the state of timber elements, cracks are a key indicator. Therefore, experimental and numerical investigations on not cracked and partly cracked timber members were carried out and analysed. The results show no influence on the stiffness and modulus of elasticity for partly cracked beams. The experimental results were used for the development of analytical and validation the numerical solutions for the assessment of the residual load carrying capacity of cracked timber members. Several models predicting the residual load carrying capacity depending on the crack situation are presented.
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Evaluation of the Block Shear Resistance of Glulam Manufactured from Borate-Treated Lamina Wthout Planing After Treatment

https://research.thinkwood.com/en/permalink/catalogue367
Year of Publication
2015
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Bridges and Spans
Author
Stirling, Rod
Feng, Martin
Morris, Paul
Organization
FPInnovations
Year of Publication
2015
Country of Publication
Canada
Format
Report
Material
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Bridges and Spans
Topic
Mechanical Properties
Keywords
Preservative
Borate
Canada
Shear Resistance
Polyurethane
Language
English
Research Status
Complete
Summary
Effective preservative treatments for Canadian glulam products are needed to maintain markets for mass timber on building facades, access markets with significant termite hazards, and expand markets for wood bridges. For all three applications, borate-treatment of lamina before gluing would be preferred as it would lead to maximum preservative penetration. However, the need to plane after treatment and prior to gluing removes the best-treated part of the wood, and creates a disposal issue for treated planer shavings. The present research evaluates the block shear resistance of glulam prepared from untreated and borate-treated lamina with a polyurethane adhesive. Borate treatment was associated with a small but statistically significant loss in median shear strength when evaluated dry; however, there was no difference between the performance of untreated and borate-treated samples when exposed to the vacuum-pressure soak/dry or the boil-dry-freeze/dry procedures. Further work is needed to modify the composition or application of the resin to improve shear strength for glulam applications and ensure consistent performance. However, overall, these data indicate that samples prepared from borate-treated lamina perform similarly in terms of block shear resistance to those prepared from untreated lamina.
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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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10 records – page 1 of 1.