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Factors Influencing Choice of Wooden Frames for Construction of Multi-Story Buildings in Sweden

https://research.thinkwood.com/en/permalink/catalogue3394
Year of Publication
2023
Topic
General Information
Author
Bahrami, Alireza
Jakobsson, Jonas
Söderroos, Tobias
Organization
University of Gävle
Publisher
MDPI
Year of Publication
2023
Format
Journal Article
Topic
General Information
Keywords
Wooden Frame
Multi-story Building
Building Environment
Moisture
Cost
Climate
Stability
Research Status
Complete
Series
Buildings
Summary
Construction of buildings with wooden frames higher than two stories has been permitted in Sweden since 1994. As construction of multi-story buildings with wooden frames is relatively new, people in the construction industry are more likely to construct these buildings with concrete frames. The current research evaluates the factors influencing the choice of wooden frames for construction of multi-story buildings in Sweden. The purpose of this study is to explain which advantages and disadvantages construction companies in Sweden consider with wooden construction and to highlight the factors for why multi-story buildings are built with wood to a lesser extent than with other materials. The main goal is to investigate what factors or assumptions construction companies base their decisions on, and whether experience and competence in wooden frames for construction of multi-story buildings are considered in short supply in Sweden today. The chosen method for this research is a descriptive survey study with a qualitative and quantitative approach. The survey is based on respondents from five leading building companies in Sweden with regard to the companies’ revenue. The respondents had either previous experience in constructing multi-story buildings with wooden frames, experienced respondents (ERs), or no experience, unexperienced respondents (UERs). 63% of the respondents were ERs, while 37% of them were UERs. It is resulted that the respondents think there is a lack of competence and experience in wooden frames for construction of multi-story buildings in Sweden. Factors that have the greatest impact on decisions to construct with wooden frames are positive environmental and climatic aspects as well as production advantages. Factors that are considered as major obstacles to construct with wooden frames are cost, acoustics, and moisture problems.
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Environmental Impact of a Mono-Material Timber Building Envelope with Enhanced Energy Performance

https://research.thinkwood.com/en/permalink/catalogue3395
Year of Publication
2023
Topic
Energy Performance
Author
Bucklin, Oliver
Bari, Roberta Di
Amtsberg, Felix
Menges, Achim
Organization
University of Stuttgart
Publisher
MDPI
Year of Publication
2023
Format
Journal Article
Topic
Energy Performance
Keywords
Computional Design
Digital Fabrication
Sustainable Construction
Building Physics
Research Status
Complete
Series
Sustainability
Summary
Broader adoption of timber construction is a strategy for reducing negative greenhouse gas (GHG) emissions created by the construction industry. This paper proposes a novel solid timber building envelope that uses computational design and digital fabrication to improve buildings’ energy performance. Timber beams are sawn with deep slits that improve thermal insulation and are milled with various joints for airtight, structural connections. To minimize embedded energy and to simplify disposal, the envelope is assembled without adhesives or metal fasteners. The building envelope is evaluated for thermal resistance and airtightness, and fabrication is evaluated for duration and power output during sawing. Finally, a Lifecycle Assessment (LCA) is carried out. The Global Warming Potential (GWP) is compared to that of other wood envelope systems with similar thermal conductance. Compared to other timber constructions with similar building physics properties, the proposed system showed lower GWP values (-15.63 kg CO2 eq./m² construction). The development and analysis demonstrate the potential to use digitally controlled subtractive manufacturing for improving the quality of solid timber to achieve higher environmental performance in building envelopes. However, further design and fabrication optimizations may be necessary to reduce required materials and production energy.
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Experimental analysis of timber-concrete composite behaviour with synthetic fibres

https://research.thinkwood.com/en/permalink/catalogue3396
Year of Publication
2023
Topic
Mechanical Properties
Material
Timber-Concrete Composite
Application
Floors
Author
Buka-Vaivade, K
Serdjuks, D
Zvirina, D
Pakrastins, L
Organization
Riga Technical University
Publisher
IOP Publishing
Year of Publication
2023
Format
Conference Paper
Material
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Synthetic Fibre
Bending Test
Conference
5th International Conference: Innovative Materials, Structures and Technologies (IMST 2022)
Research Status
Complete
Series
Journal of Physics: Conference Series
Summary
With the growing importance of the principles of sustainable construction, the use of load-bearing timber-concrete composite structures is becoming increasingly popular. Timber-concrete composite offers wider possibilities for the use of timber in construction, especially for large-span structures. The most significant benefit from combining these materials can be obtained by providing a rigid connection between the timber and concrete layers, which can be obtained by the adhesive timber-to-concrete connection produced by the proposed stone chips method. A sustainable solution involves the abandonment of steel longitudinal reinforcement. The use of such a solution in practice is often associated with fears of a fragile collapse. Therefore, the issue of how to increase the safety factor of the proposed material is topical now. The experimental investigation is made to determine the effect of synthetic fibre use on timber-concrete composite behaviour by testing a series of timber-concrete composite specimens with and without fibres in the concrete layer. The obtained results show that adding 0.5 % of synthetic macro fibres allows to abandon the use of longitudinal steel reinforcement and prevents the formation of large cracks in concrete and the disintegration of the concrete layer in case of collapse.
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Modeling of Cross-Laminated Timber (CLT) panels loaded with combined out-of-plane bending and compression

https://research.thinkwood.com/en/permalink/catalogue2842
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Columns
Walls
Author
Huang, Zirui
Huang, Dongsheng
Chui, Ying Hei
Shen, Yurong
Daneshvar, Hossein
Sheng, Baolu
Chen, Zhongfan
Organization
Southeast University
University of Alberta
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Columns
Walls
Topic
Mechanical Properties
Keywords
Rolling Shear
Beam-and-Column
Analytical Model
Load-Carrying Capacity
Research Status
Complete
Series
Engineering Structures
Summary
Rolling shear is one of the major concerns that significantly impact the performance of CLT walls if they are subjected to combined out-of-plane bending and compression loads. Because the effects of rolling shear and out-of-plane bending are coupled to each other, prediction of the load-carrying capacity of CLT wall is always a challenge for the design of CLT structures. Current design codes employ an Ayrton-Perry type interaction equation as the failure criterion to check the safety of a CLT panel loaded with combined bending and compression. Nevertheless, there is no model available to predict their load-carrying capacity. The presented work aims at developing an analytical model to predict the load-carrying capacity of CLT wall loaded with combined out-of-plane bending and compression. In total 12 five-layer CLT panels loaded with different initial load eccentricities were tested to investigate the failure modes. Observed during the test were two ultimate failure modes, i.e., compression crush on the concave side and tension rupture in convex side. Based on these failure modes and deeming the test member as a beam-column, an analytical model which takes rolling shear effects into account to predict the load-carry capacity of CLT compression-bending members was developed. An explicit formula based on compression failure mode was proposed. The model is capable of determining the distribution of rolling shear stress along longitudinal direction, rolling shear-induced axial force and moments in CLT beam-columns. By calculating the load-carrying capacities of the specimens tested in this study as well as the additional three- and seven-layer specimens tested by another studies, it was found that the compression failure mode-based formula can provide good agreements with the test results.
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Comparative Life Cycle Assessment of Mass Timber and Concrete Residential Buildings: A Case Study in China

https://research.thinkwood.com/en/permalink/catalogue2884
Year of Publication
2022
Topic
Environmental Impact
Material
CLT (Cross-Laminated Timber)
Author
Chen, Cindy
Pierobon, Francesca
Jones, Susan
Maples, Ian
Gong, Yingchun
Ganguly, Indroneil
Organization
Portland State University
University of Washington
Editor
Caggiano, Antonio
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Environmental Impact
Keywords
Mass Timber
Embodied Carbon
Climate Change
Built Environment
Life Cycle Analysis
Research Status
Complete
Series
Sustainability
Summary
As the population continues to grow in China’s urban settings, the building sector contributes to increasing levels of greenhouse gas (GHG) emissions. Concrete and steel are the two most common construction materials used in China and account for 60% of the carbon emissions among all building components. Mass timber is recognized as an alternative building material to concrete and steel, characterized by better environmental performance and unique structural features. Nonetheless, research associated with mass timber buildings is still lacking in China. Quantifying the emission mitigation potentials of using mass timber in new buildings can help accelerate associated policy development and provide valuable references for developing more sustainable constructions in China. This study used a life cycle assessment (LCA) approach to compare the environmental impacts of a baseline concrete building and a functionally equivalent timber building that uses cross-laminated timber as the primary material. A cradle-to-gate LCA model was developed based on onsite interviews and surveys collected in China, existing publications, and geography-specific life cycle inventory data. The results show that the timber building achieved a 25% reduction in global warming potential compared to its concrete counterpart. The environmental performance of timber buildings can be further improved through local sourcing, enhanced logistics, and manufacturing optimizations.
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Increasing Mass Timber Consumption in the U.S. and Sustainable Timber Supply

https://research.thinkwood.com/en/permalink/catalogue2888
Year of Publication
2022
Topic
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Comnick, Jeff
Rogers, Luke
Wheiler, Kent
Organization
University of Washington
Editor
Lauteri, Marco
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Market and Adoption
Keywords
Mass Timber
Embodied Carbon
Sustainable Timber Supply
Forest Inventory
Reforestation
Research Status
Complete
Series
Sustainability
Summary
Mass timber products are growing in popularity as a substitute for steel and concrete, reducing embodied carbon in the built environment. This trend has raised questions about the sustainability of the U.S. timber supply. Our research addresses concerns that rising demand for mass timber products may result in unsustainable levels of harvesting in coniferous forests in the United States. Using U.S. Department of Agriculture U.S. Forest Service Forest Inventory and Analysis (FIA) data, incremental U.S. softwood (coniferous) timber harvests were projected to supply a high-volume estimate of mass timber and dimensional lumber consumption in 2035. Growth in reserve forests and riparian zones was excluded, and low confidence intervals were used for timber growth estimates, compared with high confidence intervals for harvest and consumption estimates. Results were considered for the U.S. in total and by three geographic regions (North, South, and West). In total, forest inventory growth in America exceeds timber harvests including incremental mass timber volumes. Even the most optimistic projections of mass timber growth will not exceed the lowest expected annual increases in the nation’s harvestable coniferous timber inventory.
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Modeling approach to estimate the bending strength and failure mechanisms of glued laminated timber beams

https://research.thinkwood.com/en/permalink/catalogue2939
Year of Publication
2022
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Vida, Christoffer
Lukacevic, Markus
Eberhardsteiner, Josef
Füssl, Josef
Organization
TU Wien
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Mechanical Properties
Keywords
Extended Finite Element Method
Bending Strength
Size Effect
Laminating Effect
Failure Mechanism
Research Status
Complete
Series
Engineering Structures
Summary
The numerical simulation of four-point bending tests on glued laminated timber (GLT) beams requires an adequate description of the material behavior and of relevant failure mechanisms. The wooden lamellas, building up the GLT element, include knots, as a result of the natural tree growth process, which significantly affect the mechanical behavior. The variability of the morphology and arrangement of these knots lead to a large fluctuation, especially of strength properties, along the wooden lamellas. This leads to complex and, in general, quite brittle structural failure mechanisms of the GLT element. Such failure mechanisms can numerically be described with discrete cracks, using the framework of the extended finite element method (XFEM) for cracks without predefined positions or cohesive surfaces for cracks with predefined positions. In this work, a modeling approach to reliably estimate the bending strength and failure mechanisms of GLT beams subjected to four-point bending tests is proposed. Herein, the approach is validated by simulating replications of experimentally tested GLT beams of two beam sizes and strength classes, where each knot group is considered as a section with reduced individual stiffness and strength in exactly the same position as in the real beam. The results show that the application of quasi-brittle material failure may still result in a brittle global failure of GLT beams. The present study exemplarily shows how valuable insight into progressive failure processes can be gained by allowing the formation of continuous crack patterns. Moreover, a refined consideration of the knot geometries with such sophisticated realizations of discrete cracks may be able to simulate the actual failure mechanisms even more precisely.
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Out-of-Plane Tensile Properties of Cross Laminated Timber (CLT)

https://research.thinkwood.com/en/permalink/catalogue2940
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Brandner, Reinhard
Jantscher, Lukas
Organization
Graz University of Technology
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Keywords
Out-Of-Plane Tension
Size Effect
System Effects
Modulus of Elasticity
Strength
Equicorrelation
Research Status
Complete
Series
Buildings
Summary
A systematic investigation is still lacking for tension out-of-plane in cross laminated timber (CLT), as a planar timber construction product. The objectives of the present study are the determination of the tensile properties of CLT made of Norway spruce, the identification of essential product-specific influencing parameters and a comparative analysis with glulam. For this purpose, seven test series were defined, which allowed the determination of the tensile properties on board segments and thereof produced glulam and CLT specimens by varying the number of layers, layer orientation and number of elements within a layer. The orthogonal laminated structure of CLT led to between 50% and 70% higher tensile properties out-of-plane, which is explained by the different stress distribution compared to glulam; the regulation of 30% higher properties than for glulam is suggested. In addition, the lognormal distribution turned out to be a more representative distribution model for characterizing the tensile strength out-of-plane than the Weibull distribution. This was also confirmed with regard to the investigated serial and parallel system effects, in which a clearly more homogeneous behavior was found in CLT compared to glulam, which in turn can be attributed again to the different stress distributions.
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Contemporary and Novel Hold-Down Solutions for Mass Timber Shear Walls

https://research.thinkwood.com/en/permalink/catalogue2941
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Author
Tannert, Thomas
Loss, Cristiano
Organization
University of Northern British Columbia
University of British Columbia
Editor
Tullini, Nerio
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Shear Walls
Topic
Mechanical Properties
Keywords
Self-Tapping Screws
Internal-Perforated Steel Plates
Hyperelastic Bearing Pads
Proprietary Connections
Research Status
Complete
Series
Buildings
Summary
‘Mass timber’ engineered wood products in general, and cross-laminated timber in particular, are gaining popularity in residential, non-residential, as well as mid- and high-rise structural applications. These applications include lateral force-resisting systems, such as shear walls. The prospect of building larger and taller timber buildings creates structural design challenges; one of them being that lateral forces from wind and earthquakes are larger and create higher demands on the ‘hold-downs’ in shear wall buildings. These demands are multiple: strength to resist loads, lateral stiffness to minimize deflections and damage, as well as deformation compatibility to accommodate the desired system rocking behaviour during an earthquake. In this paper, contemporary and novel hold-down solutions for mass timber shear walls are presented and discussed, including recent research on internal-perforated steel plates fastened with self-drilling dowels, hyperelastic rubber pads with steel rods, and high-strength hold-downs with self-tapping screws.
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Finite Element Modeling on Shear Performance of Grouted Stud Connectors for Steel–Timber Composite Beams

https://research.thinkwood.com/en/permalink/catalogue2944
Year of Publication
2022
Topic
Mechanical Properties
Material
Steel-Timber Composite
Application
Beams
Author
Zhang, Henan
Ling, Zhibin
Organization
Suzhou University of Science and Technology
Editor
Lopes, Sérgio
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
Steel-Timber Composite
Application
Beams
Topic
Mechanical Properties
Keywords
Shear Connection
Finite Element Modeling
Grouted Stud Connections
Research Status
Complete
Series
Materials
Summary
Steel–timber composite (STC) systems are considered as an environmentally friendly alternative to steel–concrete composite (SCC) structures due to its advantages including high strength-to-weight ratio, lower carbon footprint, and fully dry construction. Bolts and screws are the most commonly used connectors in STC system; however, they probably make great demands on the accuracy of construction because of the predrilling in both the timber slabs and steel girder fangles. To address this issue, the STC connections with grouted stud connectors (GSC) were proposed in this paper. In addition, stud connectors can also provide outstanding stiffness and load-bearing capacity. The mechanical characteristic of the GSC connections was exploratorily investigated by finite element (FE) modeling. The designed parameters for the FE models include stud diameter, stud strength, angle of outer layer of cross-laminated timber (CLT) panel, tapered groove configurations, and thickness of CLT panel. The numerical results indicated that the shear capacity and stiffness of the GSC connections were mainly influenced by stud diameter, stud strength, angle of outer layer of CLT panel, and the angle of the tapered grooves. Moreover, the FE simulated shear capacity of the GSC connections were compared with the results predicted by the available calculation formulas in design codes and literatures. Finally, the group effect of the GSC connections with multiple rows of studs was discussed based on the numerical results and parametric analyses. An effective row number of studs was proposed to characterize the group effect of the GSC connections.
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Rolling Shear Properties of Cross-Laminated Timber Made from Australian Plantation Eucalyptus nitens under Planar Shear Test

https://research.thinkwood.com/en/permalink/catalogue2945
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Ettelaei, Azin
Taoum, Assaad
Shanks, Jon
Nolan, Gregory
Organization
University of Tasmania
Editor
Oliveira, Diego
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Keywords
Rolling Shear
Hardwood Plantation
Planar Shear Tests
Structural Properties
Research Status
Complete
Series
Forests
Summary
With the increasing availability of fast-growing Eucalyptus plantation logs in Australia in recent years, the timber manufacturing sector has become interested in discovering the opportunities of producing value-added timber products from this resource. Cross-laminated timber (CLT) could be a potential sustainable product recovered from this resource and supply material for commercial buildings. Shear of the inner cross-laminates, known as rolling shear, is one of the governing factors in serviceability and limit state design for this product under out-of-plane loading. This study evaluated the rolling shear (RS) properties of CLT with heterogonous layup configurations using different structural grade Eucalyptus nitens (E. nitens) timber under the planar shear test. Based on the results, Gr and tr values were shown to be significantly correlated with the density of the CLT panel. There was also a positive correlation between the RS modulus and MOR of the CLT panel. The specimens with high MOE in the top and bottom layers indicated the highest tr and Fmax values. This indicated that using high-grade boards in the top and bottom lamellae plays an important role in increasing the RS strength, whereas using them in the cross-layer has a positive contribution in increasing shear modulus. The maximum observed RS strength and modulus ranged from 2.8–3.4 MPa and 54.3–67.9 MPa, respectively, exceeding the RS characteristic values of the resource. The results obtained in this study were comparable to those recommended in European standards for softwood CLT, demonstrating the potential use for eucalypt timber boards in CLT production. This paper provides an important insight into supporting the potential engineering applications of CLT panel products fabricated with eucalypt plantation.
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Development of Creep Deformations during Service Life: A Comparison of CLT and TCC Floor Constructions

https://research.thinkwood.com/en/permalink/catalogue2955
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Author
Binder, Eva
Derkowski, Wit
Bader, Thomas
Organization
Linnæus University
Editor
Brandner, Reinhard
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Keywords
Serviceability Limit State
Gamma Method
Linear Viscoelasticity
Research Status
Complete
Series
Buildings
Summary
Cross-laminated timber (CLT) slabs in residential buildings need additional weight, e.g., in the form of screeds or gravel layers, to fulfill the criterion for the highest impact-sound class. The additional mass is, however, not exploited for the load bearing behavior, but adds additional weight and leads to an increased height of the floor construction. In this study, such a CLT floor construction with a construction height of 380 mm is compared with a composite slab consisting of a CLT plate with a concrete layer on top with a floor construction height of 330 mm. The timber concrete composite (TCC) slab has a different creep behavior than the CLT slab. Thus, the development of the time-dependent deflections over the service life are of interest. A straightforward hybrid approach is developed, which exploits advanced multiscale-based material models for the individual composite layers and a standardized structural analysis method for the structural slab to model its linear creep behavior. The introduced approach allows to investigate load redistribution between the layers of the composite structure and the evolution of the deflection of the slab during the service life. The investigated slab types show a similar deflection after 50 years, while the development of the deflections over time are different. The CLT slab has a smaller overall stiffness at the beginning but a smaller decrease in stiffness over time than the investigated TCC slab.
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Analysis and Tests of Lateral Resistance of Bolted and Screwed Connections of CLT

https://research.thinkwood.com/en/permalink/catalogue2956
Year of Publication
2022
Topic
Mechanical Properties
Connections
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Huo, Liangliang
Zhu, Enchun
Niu, Shuang
Wu, Guofang
Organization
Harbin Institute of Technology
China Academy of Forestry
Editor
Ozarska, Barbara
Monaco, Angela
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Mechanical Properties
Connections
Keywords
Lateral Resistance
European Yield Model
Bolt Connection
Screw Connectors
Emdedment Stress
Research Status
Complete
Series
Forests
Summary
The lateral resistance of dowel-type connections with CLT is related to its lay-up, species of the laminations and even the manufacture method. Treating the CLT as homogeneous material, current methods develop new equations through test results or make use of the existing equations for the embedment strength already used in design codes; thus, the lateral resistance of dowel-type connections of CLT can be calculated. This kind of approach does not take the embedment stress distribution into account, which may lead to inaccuracy in predicting the lateral resistance and yield mode of the dowel-type connections in CLT. In this study, tests of the bolted connections and the screwed connections of CLT were conducted by considering the effects of the orientation of the laminations, the thickness of the connected members, the fastener diameter and strength of the materials. The material properties including yield strength of the fasteners and embedment strength of the CLT laminations were also tested. Using analysis of the dowel-type connections of CLT by introducing the equivalent embedment stress distribution, equations for the lateral resistance of the connections based on the European Yield Model were developed. The predicted lateral resistance and yield modes were in good agreement with the test results; the correctness and the feasibility of the equations were thus validated.
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Mechanical Behavior of GFRP Dowel Connections to Cross Laminated Timber-CLT Panels

https://research.thinkwood.com/en/permalink/catalogue2957
Year of Publication
2022
Topic
Connections
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Almeida, Amanda
Moura, Jorge
Organization
Maringá State University
Londrina State University
Editor
Knapic, Sofia
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Connections
Keywords
GFRP
Dowel-Type Connections
Panel-to-Panel
Design Methodology
Push-Out Tests
Research Status
Complete
Series
Forests
Summary
Sustainability issues are driving the civil construction industry to adopt and study more environmentally friendly technologies as an alternative to traditional masonry/concrete construction. In this context, plantation wood especially stands out as a constituent of the cross-laminated timber (CLT) system, laminated wood glued in perpendicular layers forming a solid-wood structural panel. CLT panels are commonly connected by screws or nails, and several authors have investigated the behavior of these connections. Glass-fiber-reinforced polymer (GFRP) dowels have been used to connect wooden structures, and have presented excellent performance results; however, they have not yet been tested in CLT. Therefore, the objective of this study is to analyze the glass-fiber-reinforced polymer (GFRP)-doweled connections between CLT panels. The specimens were submitted to monotonic shear loading, following the test protocol described in EN 26891-1991. Two configurations of adjacent five-layer panels were tested: flat-butt connections with 45° dowels (x, y, and z axes), and half-lap connections with 90° dowels. The results were evaluated according to the mechanical connection properties of strength, stiffness, and ductility ratio. The results showed higher stiffness for butt-end connections. In terms of strength, the half-lap connections were stronger than the butt-end connections.
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Differential Material Movement in Tall Mass Timber Structures

https://research.thinkwood.com/en/permalink/catalogue2982
Year of Publication
2022
Topic
Moisture
Application
Wood Building Systems
Author
Racine, Josephine
Lumpkin, Bryce
McLain, Richard
Organization
Fast + Epp
WoodWorks
Year of Publication
2022
Format
Report
Application
Wood Building Systems
Topic
Moisture
Keywords
Column Movement
Vertical Movement
Creep
Settlement
Shrinkage
Crushing Perpendicular to Grain
Research Status
Complete
Summary
As the height of mass timber buildings continues to grow, a new set of design and detailing challenges arises, creating the need for new engineering solutions to achieve optimal building construction and performance. One necessary detailing consideration is vertical movement, which includes column shrinkage, joint settlement, and creep. The main concerns are the impact of deformations on vertical mechanical systems, exterior enclosures, and interior partitions, as well as differential vertical movement of timber framing systems relative to other building features such as concrete core walls and exterior façades.
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Experimental Verification of Thermal Insulation in Timber Framed Walls

https://research.thinkwood.com/en/permalink/catalogue3007
Year of Publication
2022
Topic
Moisture
Application
Walls
Author
Michálková, Daniela
Durica, Pavol
Organization
University of Zilina
Editor
Pavlik, Zbyšek
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Application
Walls
Topic
Moisture
Keywords
Timber Framed
Relative Humidity
Thermal Conductivity
Material Properties
Research Status
Complete
Series
Materials
Summary
Current environmental crisis calls for sustainable solutions in the building industry. One of the possible solutions is to incorporate timber-framed constructions into designs. Among other benefits, these structures are well established in many countries, originating in traditional building systems. This paper focuses on experimental timber-frame walls. Different wall assemblies vary in thermal insulation materials and their combinations. We investigated ten experimental wall structures that have been exposed to natural external boundary conditions since 2015. The emphasis was on their state in terms of visual deterioration, mass moisture content, and thermal conductivity coefficient. We detected several issues, including defects caused by inappropriate realization, causing local moisture increase. Material settlement in loose-fill thermal insulation was another issue. Concerning was a significant change in the thermal conductivity of wood fiber insulation, where the current value almost doubled in one case compared to the design value determined by the producer.
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Cross Laminated Timber (CLT) manufactured with European oak recovered from demolition: Structural properties and non-destructive evaluation

https://research.thinkwood.com/en/permalink/catalogue3008
Year of Publication
2022
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Llana, Daniel
González-Alegre, Violeta
Portela, María
Íñiguez-González, Guillermo
Organization
Universidad Politécnica de Madrid
Universidad de Santiago de Compostela
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Cascading
Circular Economy
Non-Destructive Testing
Reclaimed
Recycling
Reuse
Salvaged
Secondary Timber
Research Status
Complete
Series
Construction and Building Materials
Summary
The demolition sector generates a large amount of timber waste that could be directly reused or recycled in other products for structural purposes. Timber should be graded before it is used for structural purposes, and visual strength grading standards designed for new timber do not properly grade recovered timber. Cross Laminated Timber (CLT) is now one of the most common wood products used in construction. CLT would therefore be a good option for recycling timber due to the high quantity of material used in CLT manufacturing. This paper investigates the possibilities of using recovered timber from demolition to manufacture CLT. Twelve CLT panels from recovered and new timber were manufactured and tested. The static modulus of elasticity was found to be the same between recovered and new timber, while the bending strength of CLT from recovered timber was lower than it was for CLT from new timber. Non-destructive testing for the estimation of mechanical properties of boards and CLT panels was successfully developed.
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Free
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Experimental modal analysis of a cross-laminated timber slab

https://research.thinkwood.com/en/permalink/catalogue3009
Year of Publication
2022
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Author
Kawrza, M.
Furtmüller, T.
Adam, C.
Maderebner, R.
Organization
University of Innsbruck
Publisher
Elsevier
Year of Publication
2022
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Topic
Acoustics and Vibration
Keywords
Experimental Modal Analysis
Complex Mode Shapes
Modal Parameter Estimation
Conference
37th Danubia Adria Symposium on Advances in Experimental Mechanics
Research Status
Complete
Series
Materials Today: Proceedings
Summary
This paper presents the results of an investigation of the dynamic response of a point-supported cross-laminated timber (CLT) slab without joists with a column grid of 5.0 × 5.0 m and overall dimensions of 16.0 × 11.0 × 0.2 m. The results are based on a detailed experimental modal analysis, identifying seven modes from the dynamic response of 651 measurement points, including natural frequencies, mode shapes and damping ratios. These modal parameters exhibit a time variance that is due to environmental influences during the measurement period of two days. As a result of this disturbance effect, the determined mode shapes have a non-negligible imaginary part, which is eliminated by correcting each of the 73 measurements individually. The findings presented provide in-depth insight into the dynamic behavior of the large-scale CLT structure with point supports realized with a novel steel connector.
Online Access
Free
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Timber-concrete composite structural flooring system

https://research.thinkwood.com/en/permalink/catalogue3065
Year of Publication
2022
Topic
Mechanical Properties
Design and Systems
Material
Timber-Concrete Composite
Application
Floors
Author
Estévez-Cimadevila, J.
Martín-Gutiérrez, E.
Suárez-Riestra, F.
Otero-Chans, D.
Vázquez-Rodríguez, J. A.
Organization
Universidade da Coruña
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
Timber-Concrete Composite
Application
Floors
Topic
Mechanical Properties
Design and Systems
Keywords
Timber Flooring System
Mixed Beams
Shear Connector
Research Status
Complete
Series
Journal of Building Engineering
Summary
An integrated solution is presented for the execution of building structures using timber-concrete composite (TCC) sections that make efficient use of the mechanical properties of both materials. The system integrates flooring and shaped prefabricated beams composed of a lower flange of glued laminated timber (GLT) glued to one or more plywood or laminated veneer lumber (LVL) ribs and linked to an upper concrete slab poured in situ. The parts may be prefabricated in T shape (only one rib), in p shape (two ribs), or with multiple ribs to create wider pieces, thereby reducing installation operations. The basis of the system is the timber-concrete shear connection in the form of holes through the ribs, which are filled by the in situ-poured concrete. The connection is complemented with the arrangement of reinforcement bars through the holes. Three test campaigns were undertaken. Shear tests of the timber-concrete connection in 12 test pieces. Shear test along the wood-wood glue line (72 planes tested) and wood -plywood (24 planes tested). Delamination test of the glued planes (24 wood-wood planes and 8 wood-plywood planes). The results indicate a high strength joint, with ductile failure and high composite effect. Likewise, the shear test results along the glue line and the delamination tests show section integrity under demanding hygrothermal conditions. Preliminary sizing curves were developed considering the Gamma Method to evaluate the performance of the system. The results show the possibilities of the system, as pouring the upper slab concrete in situ makes it possible to create continuous semi-rigid joints between the elements. This gives rise to slender flooring structures, light and with high stiffness plane against horizontal forces.
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Free
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Recent progresses in wood-plastic composites: Pre-processing treatments, manufacturing techniques, recyclability and eco-friendly assessment

https://research.thinkwood.com/en/permalink/catalogue3069
Year of Publication
2022
Topic
Environmental Impact
Material
Other Materials
Author
Elsheikh, Ammar H.
Panchal, Hitesh
Shanmugan, S.
Muthuramalingam, T.
El-Kassas, Ahmed. M.
Ramesh, B.
Organization
Tanta University
Government Engineering College Patan
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
Other Materials
Topic
Environmental Impact
Keywords
Wood Plastic Composite
Material Recycling
Treatment Techniques
Ecofriendly Manufacturing
Research Status
Complete
Series
Cleaner Engineering and Technology
Summary
Wood-plastic composites (WPCs) have shown promising domestic and industrial applications. Both virgin and waste materials have been used as matrix and reinforcement materials in WPCs manufacturing which enhances the eco-efficiency of WPCs products. This study presents a comprehensive review on the WPCs manufacturing techniques including pre-processing of the composite ingredients and post-processing of the WPCs products. Three main types of pre-processing techniques have been discussed; chemical, mechanical, and thermal treatments. Conventional manufacturing techniques of WPCs such as extrusion molding, injection molding, compression molding, stir casting, and hot-press method have been presented. In addition, advanced manufacturing techniques such as selective laser sintering have been briefly discussed. The recycling of WPC is also discussed. Eco-friendly assessment of WPCs has been also introduced. Important conclusions and the future research trends have been mentioned in the end of the article.
Online Access
Free
Resource Link
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