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Bamboo/Wood Composites and Structures Shear and Normal Strain Distributions in Multilayer Composite Laminated Panels under Out-of-Plane Bending

https://research.thinkwood.com/en/permalink/catalogue2769
Year of Publication
2021
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Niederwestberg, Jan
Zhou, Jianhui
Chui, Ying Hei
Huang, Dongsheng
Publisher
Hindawi Publishing Corporation
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Three Point Bending Test
Shear Test
Digital Image Correlation
Strain
Shear Analogy
Finite Element Modelling
Stress
Language
English
Research Status
Complete
Series
Advances in Civil Engineering
Summary
Innovative mass timber panels, known as composite laminated panels (CLP), have been developed using lumber and laminated strand lumber (LSL) laminates. In this study, strain distributions of various 5-layer CLP and cross-laminated timber (CLT) were investigated by experimental and two modelling methods. Seven (7) different panel types were tested in third-point bending and short-span shear tests. During the tests, the digital imaging correlation (DIC) technique was used to measure the normal and shear strain in areas of interest. Evaluated component properties were used to determine strain distributions based on the shear analogy method and finite element (FE) modelling. The calculated theoretical strain distributions were compared with the DIC test results to evaluate the validity of strain distributions predicted by the analytical model (shear analogy) and numerical model (FE analysis). In addition, the influence of the test setup on the shear strain distribution was investigated. Results showed that the DIC strain distributions agreed well with the ones calculated by the shear analogy method and FE analysis. Both theoretical methods agree well with the test results in terms of strain distribution shape and magnitude. While the shear analogy method shows limitations when it comes to local strain close to the supports or gaps, the FE analysis reflects these strain shifts well. The findings support that the shear analogy is generally applicable for the stress and strain determination of CLP and CLT for structural design, while an FE analysis can be beneficial when it comes to the evaluation of localized stresses and strains. Due to the influence of compression at a support, the shear strain distribution near the support location is not symmetric. This is confirmed by the FE method.
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Three-Dimensional Numerical Calculation Model for Static Behavior Simulation of Cross-Laminated Timber Plates under Thermal Environment

https://research.thinkwood.com/en/permalink/catalogue2766
Year of Publication
2021
Topic
Fire
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Hu, Wenliang
Hou, Wei
Zhu, Zhao
Huang, Xuhui
Publisher
Hindawi Publishing Corporation
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Fire
Mechanical Properties
Keywords
Finite Element Method (FEM)
Thermal Behaviour
Thermal Environment
Deformation
Load Bearing Capacity
Language
English
Research Status
Complete
Series
Mathematical Problems in Engineering
Summary
Cross-laminated timber (CLT) is well known as an interesting technical and economical product for modern wood structures. The use of CLT for modern construction industry has become increasingly popular in particular for residential timber buildings. Analyzing the CLT behavior in high thermal environment has attracted scholars’ attention. Thermal environment greatly influences the CLT properties and load bearing capacity of CLT, and the investigation can form the basis for predicting the structural response of such CLT-based structures. In the present work, the finite element method (FEM) is employed to analyze the thermal influence on the deformation of CLT. Furthermore, several factors were taken into consideration, including board layer number, hole conformation, and hole position, respectively. In order to determine the influence, several numerical models for different calculation were established. The calculation process was validated by comparing with published data. The performance is quantified by demonstrating the temperature distribution and structural deformation.
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Behavior of Strengthened Timber Concrete Composite Under Axial Loads

https://research.thinkwood.com/en/permalink/catalogue2778
Year of Publication
2021
Topic
Mechanical Properties
Material
Timber-Concrete Composite
Author
El-Salakawy, Tarek
Gamal, Amr
Publisher
ScienceDirect
Year of Publication
2021
Format
Journal Article
Material
Timber-Concrete Composite
Topic
Mechanical Properties
Keywords
Axial Loading
Strengthening
Wire Mesh
Epoxy
Modulus of Elasticity
Failure Mode
Ductility
Post Failure Behavior
Language
English
Research Status
Complete
Series
Case Studies in Construction Materials
Summary
The research study focuses on different strengthening techniques for timber concrete composites (TCC) using different types of wire and wire mesh integrated with a layer of epoxy on a timber core embedded in concrete using experimental and analytical procedure. The impact of TCC on axial compression performance, modulus of elasticity, failure mode and post failure behavior and ductility were compared to reference concrete specimens. Different types of wire and wire mesh used in strengthening of the timber core, timber core size and reinforcement in the concrete cylinder were all parameters considered in this study. Timing of application of the epoxy on the wire strengthened timber core was very important. For structural applications, where the weight reduction and ductility as well as post failure endurance are essential, the development of this composite is recommended. The ratio of the ductility index to the weight is discussed. The light weight of the timber composite, and the increased ductility were noted in this study. An equation to estimate the axial compression capacity of the strengthened timber concrete composite was developed in this study. This study will pave the way for further applications for timber concrete composite aiming at reducing dead weight of concrete and the reducing the amount of concrete and steel in construction.
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Experimental Analysis of Passively and Actively Reinforced Glued-laminated Timber with Focus on Ductility

https://research.thinkwood.com/en/permalink/catalogue2823
Year of Publication
2021
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Livas, Charalampos
Ekevad, Mats
Öhman, Micael
Publisher
Taylor&Francis Online
Year of Publication
2021
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Reinforcement
Ductility
Bending Test
Steel
Language
English
Research Status
Complete
Series
Wood Material Science & Engineering
Summary
When glued-laminated timber are subjected to bending moment, they usually fail in a brittle way in the tension zone before the compressive zone reaches the compressive strength of wood. This means that the compression strength of wood is not fully exploited. By reinforcing the tension zone, the failure mode of glued-laminated timber can be changed from tensile to compressive. As a result, by utilizing the higher compressive strength, reinforced glued-laminated timber become stronger and the failure mode becomes compressive and ductile. This paper presents experimental results of the effect of steel reinforcements in the tension zone of glued-laminated timber. Four passively reinforced beams, four actively reinforced beams, and seven unreinforced beams were tested to failure in four-point bending tests. The experimental results confirmed the brittle tension failure in the unreinforced beams as well as the ductile and compressive failure in the reinforced beams. Furthermore, the experiments revealed the increase of the passively and the actively reinforced glued-laminated timber relative to the reference beams for strengths (26% and 39%) and stiffnesses (30% and 11%). Ductilities were increased from 7.7% for the reference beams to 90% and 75% for the passively and the actively reinforced glued-laminated timber, respectively.
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Advancing Knowledge of Mid-ply Shear Walls: Mid-Ply Shear Wall Fire Resistance Testing

https://research.thinkwood.com/en/permalink/catalogue2808
Year of Publication
2021
Topic
Fire
Material
Light Frame (Lumber+Panels)
Application
Shear Walls
Author
Ranger, Lindsay
Dagenais, Christian
Organization
FPInnovations
Year of Publication
2021
Country of Publication
Canada
Format
Report
Material
Light Frame (Lumber+Panels)
Application
Shear Walls
Topic
Fire
Keywords
Shear Walls
Fire Resistance Rating
Mid-Rise
Midply Wall
Language
English
Research Status
Complete
Summary
The objective of this research is to address a knowledge gap related to fire performance of midply shear walls. Testing has already been done to establish the structural performance of these assemblies. To ensure their safe implementation and their broad acceptance, this project will establish fire resistance ratings for midply shear walls. Fire tests will provide information for the development of design considerations for midply shear walls and confirm that they can achieve at least 1-hour fire-resistance ratings that are required for use in mid-rise buildings. This research will support greater adoption of mid-rise residential and non-residential wood-frame construction and improve competition with similar buildings of noncombustible construction. This work will also support the development of the APA system report for midply walls, which will be a design guideline for using midply walls in North America.
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Nested Buildings: An Innovative Strategy for the Integrated Seismic and Energy Retrofit of Existing Masonry Buildings with CLT Panels

https://research.thinkwood.com/en/permalink/catalogue2770
Year of Publication
2021
Topic
Design and Systems
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Hybrid Building Systems
Author
Valluzzi, Maria Rosa
Saler, Elisa
Vignato, Alberto
Salvalaggio, Matteo
Croatto, Giorgio
Dorigatti, Giorgia
Turrini, Umberto
Publisher
MDPI
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Hybrid Building Systems
Topic
Design and Systems
Seismic
Keywords
Nested Buildings
Seismic Retrofitting
Energy Efficiency
Integrated Intervention
Built Heritage
Masonry Buildings
Panels
Hybrid Structures
Italy
Language
English
Research Status
Complete
Series
Sustainability
Summary
The Italian building heritage is aged and inadequate to the high-performance levels required nowadays in terms of energy efficiency and seismic response. Innovative techniques are generating a strong interest, especially in terms of multi-level approaches and solution optimizations. Among these, Nested Buildings, an integrated intervention approach which preserves the external existing structure and provides a new structural system inside, aim at improving both energy and structural performances. The research presented hereinafter focuses on the strengthening of unreinforced masonry (URM) buildings with cross-laminated timber (CLT) panels, thanks to their lightweight, high stiffness, and good hygrothermal characteristics. The improvement of the hygrothermal performance was investigated through a 2D-model analyzed in the dynamic regime, which showed a general decreasing in the overall thermal transmittance for the retrofitted configurations. Then, to evaluate the seismic behavior of the coupled system, a parametric linear static analysis was implemented for both in-plane and out-of-plane directions, considering various masonry types and connector spacings. Results showed the efficiency of the intervention to improve the in-plane response of walls, thus validating possible applications to existing URM buildings, where local overturning mechanisms are prevented by either sufficient construction details or specific solutions. View Full-Text
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Technical Guide for Evaluation of Seismic Force Resisting Systems and Their Force Modification Factors for Use in the National Building Code of Canada with Concepts Illustrated Using a Cantilevered Wood CLT Shear Wall Example

https://research.thinkwood.com/en/permalink/catalogue2804
Year of Publication
2021
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
DeVall, Ron
Popovski, Marjan
McFadden, Jasmine
Organization
National Research Council Canada, Canadian Construction Materials Centre
Publisher
National Research Council Canada
Year of Publication
2021
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Keywords
Seismic Force Resisting System
Force Modification Factor
Ductility Factor
Overstrength
Non-linear Dynamic Analysis
National Building Code of Canada
Alternative Design Solution
Shear Walls
Language
English
Research Status
Complete
ISBN
978-0-660-39263-9
Summary
The objective of this guideline is to provide a simple, systematic, and sufficient procedure for evaluating the performance of Seismic Force Resisting Systems (SFRSs) and to determine the appropriate ductilityrelated (Rd) and over-strength related (Ro) force modification factors for implementation in the National Building Code of Canada (NBC). The procedure relies on the application of non-linear dynamic analysis for quantification of the seismic performance of the SFRS. Note that the procedure is also suitable for assessing force modification factors (RdRo values) of systems already implemented in the NBC. The audience for this guideline are those (called the “project study team” in this document) who submit proposals for new SFRSs with defined RdRo values to the NBC for inclusion in Subsection 4.1.8., Earthquake Loads and Effects, of Division B of the NBC. This guideline can also be used by a team performing an alternative design solution for a specific project and seeking acceptance from authority having jurisdiction. In such cases, not all aspects of this guideline (e.g., having different archetypes) will be needed.
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Projected Cross-Laminated Timber Demand and Lumber Supply Analysis

https://research.thinkwood.com/en/permalink/catalogue2767
Year of Publication
2021
Topic
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Author
Brandt, Kristin
Latta, Greg
Camenzind, Dane
Dolan, James Daniel
Bender, Donald
Wilson, Alex
Wolcott, Michael
Publisher
North Carolina State University
Year of Publication
2021
Country of Publication
United States
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Market and Adoption
Keywords
Demand
Lumber Supply
Market Penetration
United States
Language
English
Research Status
Complete
Series
BioResources
Summary
The use of cross-laminated lumber (CLT) for building construction has gained interest in the United States (US) and Canada. Although anecdotal market size claims exist, few quantitative studies have estimated the potential market size or discussed the impact of CLT on lumber supply. This paper presents a method to quantify CLT markets and lumber supplies based on data for the Northwest US. The western US was chosen for its early adoption of CLT combined with a long history of commercial timber construction. Structural designs of archetype buildings were combined with projected multifamily residential and commercial building construction to estimate the demand for CLT. These figures were reduced to account for assumptions that address market penetration and population density. In the case study for the Northwest, the total potential market is less than the existing CLT production in western North America. Thus, the demand region was expanded to include the US and Canada west of the Rocky Mountains, resulting in an estimated demand of 800,000 m3/yr by 2030. A regional lumber supply study suggests that the lumber supply will support the existing CLT industry, which utilizes approximately 2% of the selected lumber classifications, with an unknown impact on lumber cost and production.
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Influence of Steel Properties on the Ductility of Doweled Timber Connections

https://research.thinkwood.com/en/permalink/catalogue2789
Year of Publication
2021
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Author
Geiser, Martin
Bergmann, M.
Follesa, Maurizio
Publisher
ScienceDirect
Year of Publication
2021
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Topic
Connections
Mechanical Properties
Keywords
Ductility
Strength
Monotonic Test
Cyclic Tests
Dowel Type Fastener
Serial Yielding
Doweled Connections
Capacity Design
Strain Hardening Ratio
Steel
Seismic
Language
English
Research Status
Complete
Series
Construction and Building Materials
Summary
In the seismic design of structures according to the dissipative structural behaviour, the connection ductility is crucial in order to ensure the desired level of energy dissipation of the overall structure. Therefore, in case of ductile zones composed of dowel-type fasteners arranged in series, it is important to ensure that all the fasteners can fully develop their energy dissipation capacity by plastic deformations. However, when different types of connections made of two symmetrical and serially arranged assemblies of dowel-type fasteners are tested, it often appears that only few fasteners fully work in the plastic region while most of the remaining ones exhibit very low yielding. Looking at the causes of this dysfunction, a possible explanation is due to the fact that the rules for the seismic design of dissipative zones in timber structures given in international codes and used in common practice often make reference only to the steel quality of the dowel-type fasteners specifying a minimum tensile strength or sometime, like is the case of the current version of Eurocode 8, only to maximum values of the dowel-type fastener diameter and of the thickness of the connected timber or wood-based members. Also, the research conducted so far about the ductile behaviour of serially arranged connections was not focused on the post-elastic properties of steel. However, for the seismic design of ductile zones of other materials, such as for example is the case of reinforced concrete walls, post-elastic characteristics of steel are required for the reinforcing bars, in order to achieve the desired dissipative behaviour. Inspired by this fact, timber connections composed of serially arranged dowels made of steel grades with different hardening ratio and elongation at maximum tensile stress were fabricated and tested. The purpose of this work is to understand if the use of steel with significant post-elastic properties may help to solve the problem of limited yielding in serially arranged dowel-type connections. The tested specimens were composed of two symmetrical timber members made of Glulam and LVL connected to two 6 mm thick slotted-in steel plates by means of 9 steel dowels with a diameter of 6.0 mm, which were subjected to monotonic and cyclic tests carried out by implementing dowels made of steel with favourable post-elastic properties. The results showed that the simultaneous yielding of two serially arranged dowelled assemblies is possible, although not fully. Moreover, assuming as reference the steel grade with the lowest post-elastic properties, the connection ductility and strength measured through monotonic and cyclic tests increased by about 30% for the steel grades with the highest hardening ratio and elongation at maximum tensile stress, whereas the displacement at maximum strength was about five times higher. In addition, it was found that confinement of the timber members and shaping of holes were crucial in order to avoid undesired and premature brittle failures and to increase the connection strength and ductility. The results obtained may be useful in order to bring a reassessment of the code requirements regarding the steel properties of ductile connections as well as of certain principles of dimensioning and detailing.
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Cyclic Response of Insulated Steel Angle Brackets Used for Cross-Laminated Timber Connections

https://research.thinkwood.com/en/permalink/catalogue2765
Year of Publication
2021
Topic
Seismic
Acoustics and Vibration
Connections
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Author
Kržan, Meta
Azinovic, Boris
Publisher
Springer
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Topic
Seismic
Acoustics and Vibration
Connections
Keywords
Angle Bracket
Sound Insulation
Insulation
Monotonic Test
Cyclic Tests
Wall-to-Floor
Stiffness
Load Bearing Capacity
Shear
Tensile
Language
English
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
In cross-laminated timber (CLT) buildings, in order to reduce the disturbing transmission of sound over the flanking parts, special insulation layers are used between the CLT walls and slabs, together with insulated angle-bracket connections. However, the influence of such CLT connections and insulation layers on the seismic resistance of CLT structures has not yet been studied. In this paper, experimental investigation on CLT panels installed on insulation bedding and fastened to the CLT floor using an innovative, insulated, steel angle bracket, are presented. The novelty of the investigated angle-bracket connection is, in addition to the sound insulation, its resistance to both shear as well as uplift forces as it is intended to be used instead of traditional angle brackets and hold-down connections to simplify the construction. Therefore, monotonic and cyclic tests on the CLT wall-to-floor connections were performed in shear and tensile/compressive load direction. Specimens with and without insulation under the angle bracket and between the CLT panels were studied and compared. Tests of insulated specimens have proved that the insulation has a marginal influence on the load-bearing capacity; however, it significantly influences the stiffness characteristics. In general, the experiments have shown that the connection could also be used for seismic resistant CLT structures, although some minor improvements should be made.
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10 records – page 1 of 1.