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2404 records – page 1 of 241.

Analysis and enhancement of the new Eurocode 5 formulations for the lateral elastic deformation of LTF and CLT walls

https://research.thinkwood.com/en/permalink/catalogue3311
Year of Publication
2023
Topic
Mechanical Properties
Design and Systems
Material
CLT (Cross-Laminated Timber)
Author
Aloisio, Angelo
Boggian, Francesco
Sævareid, Håkon Østraat
Bjørkedal, Johan
Tomasi, Roberto
Organization
Norwegian University of Life Sciences
Università degli Studi di Trento
Università degli Studi dell’Aquila
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Design and Systems
Keywords
Light Timber Frames
Lateral Deformation
Shear Walls
Eurocode 5
Finite Element Modelling
Research Status
Complete
Series
Structures
Summary
This paper analyses the analytical formulations for the lateral elastic deformation of Light Timber Framed (LTF) and Cross-Laminated Timber (CLT) shear walls according to the new Eurocode 5 (EC5) proposal. Finite Element (FE) models and the Standard predictions are compared by emphasizing the role of each deformation contribution. A total of 1830 comparisons between analytical and numerical estimations are carried out by exploiting the Application Programming Interface of SAP2000 to modify the FE model parameters automatically. The parametric analyses proved that the numerical and analytical predictions are pretty consistent. Furthermore, in both LTF and CLT shear walls, the estimates for in-plane shear and rigid body sliding are in excellent agreement. Conversely, the analytical formulas for kinematic rocking are generally conservative for LTF and monolithic CLT shear walls, with an approximate 18%–19% discrepancy. The analytical expressions of the upcoming EC5 perfectly match the numerical model for segmented CLT shear walls under lateral forces and no vertical load. However, the presence of the vertical load determines a significant bias. Additionally, the predictions for bending deformations are not in good agreement. Therefore, the paper discusses possible enhancements for the equations proposed in the next generation of Eurocodes for the rocking deformation of segmented CLT walls to better conform with FE predictions.
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Analysis Behavior of Openings on Full-Size Cross-Laminated Timber (CLT) Frame Shear Walls Tested Monotonically

https://research.thinkwood.com/en/permalink/catalogue3335
Year of Publication
2023
Topic
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Dungani, Rudi
Sulistyono
Karliati, Tati
Suhaya, Yoyo
Malik, Jamaludin
Alpian
Supriyati, Wahyu
Organization
Institut Teknologi Bandung
Kuningan University
Palangka Raya University
Publisher
MDPI
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Seismic
Keywords
Monotonic Test
Seismic Resistance
Wood-Frame
Opening
Research Status
Complete
Series
Forests
Summary
Walls, as components of the lateral-force-resisting system of a building, are defined as shear walls. This study aims to determine the behavior of shear wall panel cross-laminated-timber-based mangium wood (Acacia mangium Willd) (CLT-mangium) in earthquake-resistant prefabricated houses. The earthquake performance of CLT mangium frame shear walls panels has been studied using monotonic tests. The shear walls were constructed using CLT-mangium measuring 2400 mm × 1200 mm × 68 mm with various design patterns (straight sheathing, diagonal sheathing/45°, windowed shear wall with diagonal pattern and a door shear wall with a diagonal pattern). Shear wall testing was carried out using a racking test, and seismic force calculations were obtained using static equivalent earthquake analysis. CLT-mangium sheathing installed horizontally (straight sheathing) is relatively weak compared to the diagonal sheathing, but it is easier and more flexible to manufacture. The diagonal sheathing type is stronger and stiffer because it has triangulation properties, such as truss properties, but is more complicated to manufacture (less flexible). The type A design is suitable for low-intensity zones (2), and types B, D, E1 and E2 are suitable for moderate-intensity zones (3, 4), and type C is suitable for severe-intensity zones (5).
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An Investigation of the Impact of Water on Certain of the Mechanical and Physical Properties of Laminated Veneer Lumber (LVL) as Used in Construction

https://research.thinkwood.com/en/permalink/catalogue3358
Year of Publication
2023
Topic
Moisture
Material
LVL (Laminated Veneer Lumber)
Author
Juciene, Milda
Dobilaite, Vaida
Albrektas, Darius
Organization
Kaunas University of Technology
Publisher
MDPI
Year of Publication
2023
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Topic
Moisture
Keywords
Strength
Water Rise Level
Water Absorption
Research Status
Complete
Series
Applied Sciences
Summary
Timber and timber products are renewable materials that, due to their durability and strength properties, meet the requirements of the construction industry, are widely used in buildings. An analysis of the scientific literature has shown that there is a lack of detailed research that fully investigates the influence of the rate of increase of the moisture content of the timber on the mechanical and, especially, the strength properties of the LVL panels. Upon immersion into water of the bottom of the specimen, the water starts rising quite quickly at the edge of the specimen, and the first six hours are the most critical. The levels of water rise inside the LVL specimen were less significant than at the edges. It was found that water significantly affects the bending strength of the panels, which, when the strength of the wet panel compared to the strength of the dry panel, decreases to 45% after one soak cycle and almost to 52% after two soak cycles. The tensile strength of the wet specimens is ~40% less than that of the dry specimens. The strength of the panels that were dried back to their initial state was found to be sufficient again, different from the initial strength only within the error limits; the strength properties of the building structure will not be affected.
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Behavior of cross-laminated timber panels during and after an ISO-fire: An experimental analysis

https://research.thinkwood.com/en/permalink/catalogue3343
Year of Publication
2023
Topic
Fire
Material
CLT (Cross-Laminated Timber)
Author
Vairo, Maurizio
Silva, Valdir Pignatta
Icimoto, Felipe Hideyoshi
Organization
University of Sao Paulo
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Fire
Keywords
Charring
ISO-fire
Post-fire Stiffness Reduction
Cooling Phase
Finite Element Analysis
Research Status
Complete
Series
Results in Engineering
Summary
Cross-laminated timber has been used in buildings since the 1990s. In the last years, there has been a growing interest in the use of this technology, especially with the adoption of the product in increasingly taller buildings. Considering that the product is manufactured from a combustible material, wood, authorities that regulate the fire safety in buildings and the scientific community have carried out numerous research and fire tests, aiming to elaborate codes which contemplate the use of cross-laminated timber in tall buildings. This paper discusses the main results obtained from the fire resistance test of a cross-laminated timber slab carried out in the horizontal gas furnace (3.0 m × 4.0 m x 1.5 m) from the University of Sao Paulo. A vertical load of 3 kN/m2 was applied over the slab and the specimens were exposed to the standard fire curve for 30 min. In addition to the 30-min test, the research also evaluated the thermal behavior of the samples during the 24 h after the burners were turned off. Throughout the test, the slab maintained the integrity and the thermal insulation, and no falling-off of the charred layer was observed. However, the 24-h test indicated that it is mandatory to consider the loss of stiffness and strength of timber caused by the thermal wave observed during the decay phase.
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Behavior of Cross-Laminated Timber Panels Made from Fibre-Managed Eucalyptus nitens under Short-Term Serviceability Loads

https://research.thinkwood.com/en/permalink/catalogue3360
Year of Publication
2023
Topic
Mechanical Properties
Serviceability
Material
CLT (Cross-Laminated Timber)
Author
Liang, Yingwei
Taoum, Assaad
Kotlarewski, Nathan
Chan, Andrew
Holloway, Damien
Organization
University of Tasmania
Publisher
MDPI
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Serviceability
Keywords
Hardwood CLT
Serviceability Performance
Eucalyptus nitens
Vibration
Deflection
Modulus of Elasticity
Research Status
Complete
Series
Buildings
Summary
In this study, the preliminary serviceability performance of cross-laminated timber (CLT) panels constructed from fibre-managed Eucalyptus nitens (E. nitens) was investigated via bending and vibration tests. Linear four-point bending tests were performed to determine the stiffness and deflection of all CLT panels under serviceability loads. The dynamic response of CLT panels was tested using a basketball and an accelerometer. The fundamental natural frequencies of all tested panels were above the minimum frequency limit (8 Hz) when extrapolated to spans of up to 4.4 m. The configurations of E. nitens CLT panels were based on different modulus of elasticity (MOE) values for each board. Using higher MOE timber boards as the top and bottom layers can significantly increase the serviceability performance of both bending and vibration tests. The same experiments were carried out on two CLT panels made of strength class C24 Spruce-Pine-Fir to compare the serviceability performance of E. nitens CLT. The results demonstrated that E. nitens is a reliable resource for CLT manufacturing, and exhibits better serviceability performance compared to Spruce CLT. This provides more sustainable options for a species traditionally destined for pulp.
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Bending Properties and Vibration Characteristics of Dowel-Laminated Timber Panels Made with Short Salvaged Timber Elements

https://research.thinkwood.com/en/permalink/catalogue3359
Year of Publication
2023
Topic
Mechanical Properties
Material
DLT (Dowel Laminated Timber)
Author
Giordano, Lorenzo
Derikvand, Mohammad
Fink, Gerhard
Organization
Aalto University
Publisher
MDPI
Year of Publication
2023
Format
Journal Article
Material
DLT (Dowel Laminated Timber)
Topic
Mechanical Properties
Keywords
Bending Stiffness
Eigenfrequency
Damping Ratio
Salvaged Plywood
Wooden Connectors
Reuse
Circular Economy
Research Status
Complete
Series
Buildings
Summary
Salvaged timber elements often have length limitations, and therefore, their reuse in structural products normally would require additional processing and end-to-end joining. This increases the costs of reusing such materials, which makes them even less attractive to the timber sector. In the presented research, a new approach is proposed for reusing short, salvaged timber elements combined with new (full-scale) timber boards to fabricate dowel-laminated timber (DLT) panels without significant processing or end-to-end joining or gluing. In this approach, salvaged timber elements are pressed in the system in such a way that they can contribute to the bending performance of the DLT panels by resisting compression stress. In order to evaluate the effectiveness, several small-scale and large-scale DLT panels were fabricated. Salvaged plywood tenons were used as connectors. The bending stiffness of the small-scale DLT panels and the first eigenfrequency, damping ratio, bending properties, and failure modes of the large-scale DLT panels were evaluated. The results exhibited that by using the proposed approach, the short, salvaged timber elements can contribute substantially to the bending stiffness of the DLT panels without requiring end-to-end joining or gluing. On average, about a 40% increase in the bending stiffness could be achieved by pressing in the salvaged timber elements, which results in relatively similar stiffness properties compared to conventional DLT panels. One further characteristic is that the failure of the panels, and therefore the panel’s strength, is mainly governed by the quality of the full-scale timber boards instead of the salvaged ones. This can be beneficial for practical use as the qualitative assessment of the strength properties of salvaged timber becomes less critical.
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Birch plywood as gusset plates in glulam frame via mechanical connectors: A combined experimental and numerical study

https://research.thinkwood.com/en/permalink/catalogue3348
Year of Publication
2023
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Author
Wang, Yue
Wang, Tianxiang
Persson, Pontus
Hedlund, Patrik
Crocetti, Roberto
Wålinder, Magnus
Organization
KTH royal institute of technology
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Connections
Mechanical Properties
Keywords
Birch Plywood
Gusset Plate
Finite Element Method
Research Status
Complete
Series
Journal of Building Engineering
Summary
Birch is a short-lived hardwood species widespread in the Northern Hemisphere. Plywood made from birch has superior mechanical properties compared with that made from most softwoods, which makes it suitable for structural application. In this study, the feasibility of using birch plywood as gusset plates in timber-timber connections is presented. Test frames consisting of birch plywood gussets and glulam beams connected by nails were built and tested. A 2D analytical model based on truss theory and a 3D finite element model were proposed and constructed. Both models showed satisfactory agreements with the test results in terms of stiffness and strength. Tensile failure on the birch plywood gussets along the outermost row of nail holes was observed in the experiment. The observed failure modes and the stress distributions in the 3D numerical model suggest that the spreading angle (Whitmore effective width) theory should be considered in the design phase of birch plywood gusset plates. Besides, a modified spreading angle theory is proposed to both approximate the stress distribution and predict the load-bearing capacity.
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Capacity models for timber under compression perpendicular to grain with screw reinforcement

https://research.thinkwood.com/en/permalink/catalogue3372
Year of Publication
2023
Topic
Mechanical Properties
Author
Aloisio, Angelo
Ussher, Ebenezer
Fragiacomo, Massimo
Tomasi, Roberto
Organization
Università degli Studi dell’Aquila
Norwegian University of Life Sciences
Publisher
Springer
Year of Publication
2023
Format
Journal Article
Topic
Mechanical Properties
Keywords
Compression Perpendicular to the Grain
Failure Mode
Capacity Model
Eurocode Model
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
This paper compares the performance of probabilistic and deterministic capacity models for reinforced timber members under compression perpendicular to the grain. A database collecting approximately 60 test results has been compiled by reviewing research papers and master’s and doctoral theses from the past twenty years. The capacity model proposed for the next generation of Eurocodes assesses the capacity as the minimum between the values associated with two failure modes, one at the contact plate and one at the screw tips. The main drawbacks of the model are the excessive elaborateness, given its limitation in accuracy and the fallacy in predicting the observed failure modes. In detail, the failure by the screw tips seldom occurs, although it was expected in more than half of the selected specimens. The authors attempted to simplify the capacity equation by proposing a generalized expression corresponding to the failure mode at the contact plate, corrected by a factor including the effects of load and screw arrangement and geometric details of the specimen. A deterministic mechanical model obtained by multiplying the timber strength by the contact area with a given coefficient performs better than the Eurocode model, which attempts to include the effect of load diffusion (R suitable fitting (R 2 ˜ 0.27 ). A constant factor equal to 2 yields a 2 ˜ 0.76 ). The best performance is achieved with a four-term polynomial, with adimensional addends, leading to an optimum fitting (R 2 ˜ 0.82).
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Comparative CO2 emissions of concrete and timber slabs with equivalent structural performance

https://research.thinkwood.com/en/permalink/catalogue3345
Year of Publication
2023
Topic
Environmental Impact
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Author
Oh, Jae-Won
Park, Keum-Sung
Kim, Hyeon Soo
Kim, Ik
Pang, Sung-Jun
Ahn, Kyung-Sun
Oh, Jung-Kwon
Organization
Seoul National University
Korea Institute of Civil Engineering and Building Technology
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Topic
Environmental Impact
Keywords
Carbon Dioxide
Reinforced Concrete
Structural Performance
Environmental Product Declaration
Research Status
Complete
Series
Energy and Buildings
Summary
Comparing the environmental impacts of building materials at the building level can be biased because a building design is optimized for a primary structural material. To achieve objective comparisons, this study compares the environmental impact of reinforced concrete (RC), cross-laminated timber (CLT), and timber-concrete composite (TCC) at the component level with equivalent structural performance. A slab was selected as the target structure member because its design does not consider lateral forces. Equivalent structural performance was defined as the minimum quantity of slab materials for comparable span and live load conditions. The functional unit for this study was defined as a 1 m2 slab. The system boundary covered the cradle-to-gate perspective, including raw material extraction, transportation, and manufacturing. The structural design method and material design values followed the Korean building code and standards. Environmental product declaration data developed in Korea were used to evaluate the carbon footprint. The CLT emitted 75 % less carbon dioxide, the primary greenhouse gases responsible for anthropogenic climate change, compared with RC regardless of conditions, while the TCC emitted 65 % less CO2, and its environmental impact improved as the span lengthened. The results also indicated that timber slabs are thinner than concrete slabs and can be structurally rational.
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Comparative study on connection properties of shear bolt and screw of thin cross-laminated timber panel

https://research.thinkwood.com/en/permalink/catalogue3379
Year of Publication
2023
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Zhang, Daiyuan
Shen, Liming
Zhu, Xudong
Zhang, Sujun
Gong, Meng
Gao, Yuewen
Organization
Nanjing Forestry University
University of New Brunswick
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Connection Properties
Bolt
Screw
Research Status
Complete
Series
BioResources
Summary
Cross-laminated timber (CLT), a wood product with excellent shear resistance, is often used in modern timber constructions. Using the standards ASTM D1761-12 (2020) and NDS-2012 (2012), this study investigated the connection properties of shear bolts and screws in CLT panels. The specimens were made from spruce-pine-fir lumber and installed on a test platform using one high-strength bolt or eight screws, and then an upward load was applied to the top of the specimen. The results showed that the bolt connection provided a higher ultimate bearing capacity and elastic stiffness. The bolt exhibited virtually no deformation, and the CLT panel did not noticeably deteriorate when the connection was damaged. The distance between the bolt hole and the bottom of the CLT specimen and the angle between the outer-layer grain direction of the CLT panel and the load direction were both measured. Changes in the ductility coefficient value had an obvious effect on the connection performance of the shear bolts when the outer-layer grain direction of the CLT panel was consistent with the load direction. Contrastingly, when the outer-layer grain direction of the CLT panel was perpendicular to the load direction, the effect was negligible, and the yield load was nearly unchanged.
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2404 records – page 1 of 241.