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26 records – page 1 of 3.

Behavior of Timber-Concrete Composite Beams with Two Types of Steel Dowel Connectors

https://research.thinkwood.com/en/permalink/catalogue1996
Year of Publication
2018
Topic
Connections
Mechanical Properties
Material
Timber-Concrete Composite
Application
Beams

Bonding Performance of Adhesive Systems for Cross-Laminated Timber Treated with Micronized Copper Azole Type C (MCA-C)

https://research.thinkwood.com/en/permalink/catalogue2200
Year of Publication
2020
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Lim, Hyungsuk
Tripathi, Sachin
Tang, Juliet
Publisher
ScienceDirect
Year of Publication
2020
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Preservatives
Micronized Copper Azole-Type C
Bonding Performance
Delamination Tests
Block Shear Tests
Adhesives
Block Shear Strength
Wood Failure Percentage
Research Status
Complete
Series
Construction and Building Materials
Summary
The feasibility of manufacturing cross-laminated timber (CLT) from southern yellow pine (United States grown) treated with micronized copper azole type C (MCA-C) preservative was evaluated. Lumber (2x6 visually graded no. 2 boards) was treated to two retention levels (1.0 and 2.4 kg/m3 ), planed to a thickness of 35 mm, and assembled along with an untreated control group using three adhesive systems following product specifications: melamine formaldehyde (MF), resorcinol formaldehyde (RF), and one-component polyurethane (PUR). Block shear and delamination tests were conducted to examine the bonding performance in accordance with ASTM D905 and ASTM D2559 Standards, respectively. One-way analysis of variance and Kruskal-Wallis H test were conducted to evaluate the effects of preservative retention and adhesive type on block shear strength (BSS) and wood failure percentage (WFP). Regardless of adhesive type, the 1.0 kg/m3 retention treatment significantly lowered BSS compared to the untreated control. CLT composed of the laminations treated at 2.4 kg/m3 maintained BSS when PUR and RF were used but not MF. The average WFP of each CLT configuration ranged from 89% to 99%. The untreated CLT specimens did not experience any delamination under accelerated weathering cycles. The delamination rates of the treated specimens assembled using MF and RF increased with the preservative retention level, while PUR provided delamination rates less than 1% to the laminations treated at both levels. These combined data suggest that, under the conditions tested, PUR provided overall better bonding performance than MF and RF for MCA-C treated wood.
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Bonding Strength Test Method Assessment for Cross-Laminated Timber Derived Stressed-Skin Panels (CLT SSP)

https://research.thinkwood.com/en/permalink/catalogue1404
Year of Publication
2017
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Luengo, Emilio
Hermoso, Eva
Cabrero, Juan Carlos
Arriaga, Francisco
Publisher
Springer Netherlands
Year of Publication
2017
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Stressed-Skin Panels
Shear Strength
Glue Lines
Shear Tests
Bending Tests
Bonding
Research Status
Complete
Series
Materials and Structures
Summary
Different methods, including bending tests and small and medium size shear tests, were used to assess the skin to stringer glue line shear strength of Radiata Pine Cross-Laminated Timber Derived Stressed-Skin Panels (CLT SSP). Bending test shear strengths were estimated using the mechanically jointed beam theory (gamma method) for CrossLaminated Timber (CLT) panels with modifications in the layers’ effective widths, and then compared with results from the small and medium size shear tests. Small and medium size shear tests proved to be possible methods for assessing bonding strength for factory production control. The small shear tests provided lower strength values and higher scatter results than those gathered from the medium size tests. The mean shear strength results obtained from bending tests were inferior to the values obtained from the small and medium size specimens. The bending tests proved necessary for assessing the mechanical behaviour of CLT SSP.
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Concentrated Load Introduction in CLT Elements Perpendicular to Plane – Experimental and Numerical Investigations

https://research.thinkwood.com/en/permalink/catalogue1613
Year of Publication
2016
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Bogensperger, Thomas
Joebstl, Robert
Augustin, Manfred
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Bending Tests
Shear Tests
Concentrated Loads
Numerical Model
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 2341-2349
Summary
In this contribution bending and shear tests of cross laminated timber (CLT) plates under concentrated loads are presented. The so loaded structural members can fail either due to punching along a critical perimeter line in the vicinity of the concentrated load or in bending. Two test configurations were developed and investigated by linear elastic models. The obtained test results and observed failures as well as their correlation with the mechanical modeling are shown in this paper. The established numerical model was a 3D solid model with different material behavior for all acting stresses. The material behavior was implemented in a user subroutine for the FE program ABAQUS. By comparison of measured and computed load displacement curves numerical models could be discussed regarding their reliability and conclusions about missing input for an increasing accuracy of the model could be drawn.
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Deconstructable Hybrid Connections for the Next Generation of Prefabricated Mass Timber Buildings

https://research.thinkwood.com/en/permalink/catalogue2809
Year of Publication
2021
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Floors
Hybrid Building Systems
Shear Walls
Author
Shulman, Samuel
Loss, Cristiano
Organization
University of British Columbia
Year of Publication
2021
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Floors
Hybrid Building Systems
Shear Walls
Topic
Connections
Keywords
Steel Rods
Epoxy
Push-Out-Shear Tests
Prefabrication
Disassembly
Reuse
Research Status
Complete
Summary
Timber has been used for building construction for centuries, until the industrial revolution, when it was often replaced by steel and concrete or confined to low-rise housings. In the last thirty years however, thanks to the development of mass timber products and new global interest in sustainability, timber has begun to make a resurgence in the building industry. As building codes and public perception continues to change, the demand for taller and higher-performance timber buildings will only grow. Thus, a need exists for new construction technology appropriate for taller mass timber construction, as well as for fabrication and deconstruction practices that respect wood’s inherent sustainable nature. With this in mind, this research program aims to develop a new hybrid shear connection for mass timber buildings that allows for easy construction, deconstruction, and reuse of the structural elements. This report includes results of Phase 1, which focused on connections consisting of partially threaded 20M and 24M steel rods bonded into pockets formed in CLT and surrounded by thick crowns of high-strength three-component epoxy-based grout. A total of 168 specimens were designed and fabricated, and push-out shear tests carried out with a displacement-controlled monotonic loading protocol. Strength and stiffness values were assessed and effective failure modes in specimens identified. These latter, along with the recorded load-deformation curves, indicate that it is possible to develop mechanics-based design models and design formulas akin to those already used for typical dowel-type fastener timber connections. Additionally, the specimens were easily fabricated in the lab and quickly fastened to the test jig by means of nuts and washers, suggested such connections have a strong potential for prefabrication, disassembly, and reuse.
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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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Efficient Shear Transfer in Timber-Concrete Composite Bridges by Means of Grouting with Polymer Mortar

https://research.thinkwood.com/en/permalink/catalogue1694
Year of Publication
2016
Topic
Connections
Mechanical Properties
Material
Timber-Concrete Composite
Application
Bridges and Spans
Author
Kaestner, Martin
Rautenstrauch, Karl
Year of Publication
2016
Format
Conference Paper
Material
Timber-Concrete Composite
Application
Bridges and Spans
Topic
Connections
Mechanical Properties
Keywords
Polymer Mortar
Shear Tests
Bending Tests
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 4281-4290
Summary
The performance of timber-concrete composite bridge constructions crucially depends on the design of the joint between concrete deck and timber main girders. In research studies at the Bauhaus-University Weimar, innovative joining techniques based on grouting with highly-filled, tolerance-compensating polymer glue mortars have been developed to improve the shear capacity of this joint significantly. By applying a thin layer of polymer mortar on the top of the wooden main girder a continuous, slip-free connection to the timber can be realized. This layer can be utilized for the embedding of steel plates with welded-on shear studs (stud connectors), so that the joint to the concrete side is ensured by a standardised connection. The steel plates are rigidly anchored in the polymer mortar by adhesive bond and form closure. As an alternative, a slip-free grout-glued connection between concrete and timber can be realized by the glue mortar itself, so that also a continuous connection to the concrete is accessible, whereby manufacturing tolerances can easily be compensated due to the high degree of mineral filling of the polymer mortar. The paper focuses on experimental results of shear and bending tests for the new composite joint configurations.
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Elevated Temperature Effects on the Shear Performance of a Cross-Laminated Timber (CLT) Wall-to-Floor Bracket Connection

https://research.thinkwood.com/en/permalink/catalogue2106
Year of Publication
2019
Topic
Fire
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors

Evaluating Rolling Shear Strength Properties of Cross-Laminated Timber by Short-Span Bending Tests and Modified Planar Shear Tests

https://research.thinkwood.com/en/permalink/catalogue1403
Year of Publication
2017
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Li, Minghao
Publisher
Springer Japan
Year of Publication
2017
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Rolling Shear Strength
Non-Edge-Glued
Pine
Thickness
Three Point Bending Test
Planar Shear Tests
Europe
Canada
Research Status
Complete
Series
Journal of Wood Science
Summary
This paper presents an experimental study on rolling shear (RS) strength properties of non-edge-glued cross-laminated timber (CLT) made out of New Zealand Radiata pine (Pinus radiata) structural timber. CLT specimens with 35 and 20 mm thick laminations were studied to evaluate the influence of lamination thickness on the RS strength of CLT. Short-span three-point bending tests were used to introduce high RS stresses in cross layers of CLT specimens and facilitate the RS failure mechanism. Modified planar shear tests from the conventional two-plate planar shear tests were also used to evaluate the RS strength properties. It was found that two test methods yielded comparable RS strength properties and the lamination thickness significantly affected RS strength of the CLT specimens. The test results also indicated that the recommended characteristic RS strength values of CLT products in Europe and Canada might be over conservative. Also, it might be more efficient to specify different RS strength values for CLT with different lamination thickness given the minimum width-to-depth ratio of laminations is satisfied.
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The Evaluation of Panel Bond Quality and Durability of Hem-Fir Cross-Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue1377
Year of Publication
2018
Material
CLT (Cross-Laminated Timber)
Author
Wang, Brad
Wei, Peixing
Gao, Zizhen
Dai, Chunping
Publisher
Springer Berlin Heidelberg
Year of Publication
2018
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Keywords
North America
Manufacturing
Hem-Fir
Bond Quality
Durability
Delamination Tests
Block Shear Tests
One-Component Polyurethane
Emulsion Polymer Isocyanate
Applied Pressure
Wood Failure Percentage
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
To better use the second-growth wood resources in value-added applications, this work addressed the manufacturing aspects of cross-laminated timber (CLT) products from western hemlock (Tsuga heterophylla (Raf.) Sarg) and amabilis fir (Abies amabilis (Dougl.) Forbes) (or hem-fir) harvested from coastal British Columbia, Canada. Small CLT billets (nominal 610 mm×610 mm) were made to examine CLT bond quality and durability through block shear and delamination tests. Two types of adhesives, single-component polyurethane (PUR) and emulsion polymer isocyanate (EPI) and two critical applied pressure parameters (0.28 and 0.83 MPa) were adopted to manufacture hem-fir CLT. It was found that the adhesive type and applied pressure significantly affected wood failure percentage (WFP) and delamination of hem-fir CLT. When PUR adhesive was used, CLT made at 0.83 MPa pressure yielded significantly higher WFP and lower delamination than that made at 0.28 MPa pressure. The results demonstrated that despite the fact that hem-fir lumber is not particularly specified in the current North American CLT standard, it could be used for manufacturing CLT with the required panel bond quality.
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26 records – page 1 of 3.