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11 records – page 1 of 2.

Assessment of Connections in Cross-Laminated Timber Buildings Regarding Structural Robustness

https://research.thinkwood.com/en/permalink/catalogue1948
Year of Publication
2018
Topic
Connections
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Huber, Johannes
Ekevad, Mats
Berg, Sven
Girhammar, Ulf
Year of Publication
2018
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Connections
Mechanical Properties
Keywords
Finite Element Method
Deformation
Multi-Storey
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 20-23, 2018, Seoul, Republic of Korea
Summary
Cross-laminated timber makes timber buildings with an increasing number of storeys achievable. With more storeys, structural robustness needs more attention to make a building survive unforeseen events (e.g. accidents, terrorism) and save lives. For steel and concrete buildings, design methods for robustness focus on connection details. The assessment of joints in cross-laminated timber buildings regarding robustness is rather limited in the literature. The objective of this paper is to conduct an initial assessment of the connectors after the removal of a wall in a platform cross-laminated timber building. We used the finite element method and the component method for the analysis of a case building. The results indicate that the wall-to-wall and the floor-to-floor connectors may fail at low deflection levels leading to high shear loads in the floor panel above the removed wall, which might induce cracking. The removal analysis was only partially completed, but we identified an indication of the deformation behaviour of the case building. Testing and refined modelling of the connections is needed in the future to verify the results. This study may facilitate future investigations regarding robustness of multi-storey cross-laminated timber buildings.
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Diaphragm shear and diagonal compression testing of cross-laminated timber

https://research.thinkwood.com/en/permalink/catalogue2858
Year of Publication
2021
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Sharifi, Jonas
Sharifi, Zahra
Berg, Sven
Ekevad, Mats
Organization
Luleå University of Technology
Publisher
Springer
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Mechanical Properties
Keywords
Diagonal Compression Test
Diaphragm Shear Test
Shear Modulus
Research Status
Complete
Series
SN Applied Sciences
Summary
To learn the characteristics of a cross-laminated timber (CLT) panel, it is crucial to perform experimental tests. This study presents two experimental test methods to measure the in-plane shear modulus of CLT panels. This characteristic can be measured by multiple methods such as the picture frame test, the diagonal compression test, and the diaphragm shear test. In this study, the same CLT panels are tested and evaluated in the diaphragm shear test and the diagonal compression test to see if more reliable results can be achieved from the diaphragm shear test. This evaluation is done by experimental tests and finite element simulations. The theoretical pure shear simulation is used as a reference case. Finite element simulations are made for both edge glued and non-edge glued CLT panels. Nine CLT panels are tested in the diaphragm shear test and the diagonal compression test. During ideal conditions (uniform material properties and contact conditions), all three simulated methods result in an almost equal shear modulus. During the experimental testing, the diagonal compression test gives more coherent results with the expected shear modulus based on finite element simulations. Based on the diaphragm shear test results, the CLT panels behave like edge glued, but this situation is dismissed. However, during ideal conditions, the diaphragm shear test is seen as a more reliable method due to the higher proportion of shear in the measured area.
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Finite element analysis of alternative load paths to prevent disproportionate collapse in platform-type CLT floor systems

https://research.thinkwood.com/en/permalink/catalogue2901
Year of Publication
2021
Topic
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Huber, Johannes
Bita, Hercend
Tannert, Thomas
Berg, Sven
Organization
Luleå University of Technology
University of Northern British Columbia
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Design and Systems
Keywords
Mass Timber
Structural Robustness
High Fidelity Model
Progressive Collapse
Structural Integrity
Component Model
Research Status
Complete
Series
Engineering Structures
Summary
Multi-storey buildings require mitigation of consequences of unexpected or accidental events, to prevent disproportionate collapse after an initial damage. Cross-laminated timber (CLT) in platform-type construction is increasingly used for multi-storey buildings, however, the collapse behaviour and alternative load paths (ALPs) are not fully understood. A 3D non-linear component-based finite element model was developed for a platform-type CLT floor system to study the ALPs after an internal wall loss, in a pushdown analysis. The model, which accounted for connection failure, timber crushing and large displacements, was calibrated to experimental results and then adapted for boundary conditions corresponding to typical residential and office buildings. Subsequently, five parameters (floor span, connection type, vertical location of the floor, tying level, horizontal wall stiffness) were varied, to study their effects on the ALPs in 80 models. The results showed that three ALPs occurred, of which catenary action was the most dominant. Collapse resistance was mainly affected by the floor span, followed by the axial strength, stiffness and ductility of the floor-to-floor connection, the weight of the level above and the floor panel thickness. This study provides an approach to model ALPs in a platform-type CLT floor system to design disproportionate collapse resistant multi-storey CLT buildings.
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Finite Element Analysis of Bending Stiffness for Cross-Laminated Timber with Varying Board Width

https://research.thinkwood.com/en/permalink/catalogue2455
Year of Publication
2019
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Berg, Sven
Turesson, Jonas
Ekevad, Mats
Huber, Johannes
Organization
Luleå University of Technolog
Publisher
Taylor&Francis Online
Year of Publication
2019
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Finite Element Analysis
Board Width
Out-of-Plane Load
Research Status
Complete
Series
Wood Material Science & Engineering
Summary
Cross laminated timber (CLT) is a wood panelling building system that is used in construction, e.g. for floors, walls and beams. Because of the increased use of CLT, it is important to have accurate simulation models. CLT systems are simulated with one-dimensional and two-dimensional (2D) methods because they are fast and deliver practical results. However, because non-edge-glued panels cannot be modelled under 2D, these results may differ from more accurate calculations in three dimensions (3D). In this investigation, CLT panels with different width-to-thickness ratios for the boards have been simulated using the finite element method. The size of the CLT-panels was 3.0 m × 3.9 m and they had three and five laminate layers oriented 0°–90°–0° and 0°–90°–0°–90°–0°. The thicknesses of the boards were 33.33, 40.0, and 46.5 mm. The CLT panel deformation was compared by using a distributed out-of-plane load. Results showed that panels with narrow boards were less stiff than wide boards for the four-sided support setup. The results also showed that 2D models underestimate the displacement when compared to 3D models. By adjusting the stiffness factor k88, the 2D model displacement became more comparable to the 3D model.
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Finite Element Simulation of Nailed Glulam Timber Joints

https://research.thinkwood.com/en/permalink/catalogue333
Year of Publication
2015
Topic
Connections
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Author
Ekevad, Mats
Berg, Sven
Year of Publication
2015
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Beams
Topic
Connections
Mechanical Properties
Keywords
Finite Element Model
Joints
Nails
Steel Plate
Research Status
Complete
Series
Pro Ligno
Summary
This paper presents a finite element modeling method for a certain type of nailed joint between glulam beams. The joint in question is a traditional arrangement of a horizontal beam and a vertical pillar but here there is also a nailed steel plate inserted on the two sides in order to strengthen the joint. Experimental results and a comparisons of simulated and experimental results are made. The model includes the elastic and plastic orthotropic behaviour of wood and the elastic and plastic behaviour of nails. The nail joint between the steel plate and the wood is modelled as an elastic-plastic surface to surface connection with elastic-plastic properties. Also the reinforcing effect of nails in the nail-affected volume of wood is taken into consideration by raising rolling shear yield limit in the affected wood volume.The comparisons show that the model works well and give results that are comparable to experimental results.
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Impact of Board Width on In-plane Shear Stiffness of Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue2272
Year of Publication
2019
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Turesson, Jonas
Berg, Sven
Ekevad, Mats
Publisher
Elsevier
Year of Publication
2019
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
In-Plane Shear Modulus
In-Plane Shear Stiffness
Finite Element Method
Board Width
Layer Thickness
Board Gap
Research Status
Complete
Series
Engineering Structures
Summary
Board width-to-thickness ratios in non-edge-glued cross laminated timber (CLT) panels influence the in-plane shear stiffness of the panel. The objective is to show the impact of board width-to-thickness ratios for 3- and 5-layer CLT panels. Shear stiffnesses were calculated using finite element analysis and are shown as reduction factors relative to the shear stiffnesses of edge-glued CLT panels. Board width-to-thickness ratios were independently varied for outer and inner layers. Results show that the reduction factor lies in the interval of 0.6 to 0.9 for most width-to-thickness ratios. Results show also that using boards with low width-to-thickness ratios give low reduction factors. The calculated result differed by 2.9% compared to existing experimental data.
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Influence of laminate direction and glue area on in-plane shear modulus of cross-laminated timber

https://research.thinkwood.com/en/permalink/catalogue2857
Year of Publication
2020
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Author
Turesson, Jonas
Sharifi, Zahra
Berg, Sven
Ekevad, Mats
Organization
Luleå University of Technology
Publisher
Springer
Year of Publication
2020
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Walls
Topic
Mechanical Properties
Keywords
Diagonal Compression Test
Laminate Direction
Shear Modulus
Research Status
Complete
Series
SN Applied Sciences
Summary
The use of cross-laminated timber (CLT) in constructing tall buildings has increased. So, it has become crucial to get a higher in-plane stiffness in CLT panels. One way of increasing the shear modulus, G, for CLT panels can be by alternating the layers to other angles than the traditional 0° and 90°. The diagonal compression test can be used to measure the shear stiffness from which G is calculated. A general equation for calculating the G value for the CLT panels tested in the diagonal compression test was established and verified by tests, finite element simulations and external data. The equation was created from finite element simulations of full-scale CLT walls. By this equation, the influence on the G value was a factor of 2.8 and 2.0 by alternating the main laminate direction of the mid layer from the traditional 90° to 45° and 30°, respectively. From practical tests, these increases were measured to 2.9 and 1.8, respectively. Another influence on the G value was studied by the reduction of the glue area between the layers. It was shown that the pattern of the contact area was more important than the size of the contact area.
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In-plane Shear Modulus of Cross-laminated Timber by Diagonal Compression Test

https://research.thinkwood.com/en/permalink/catalogue2420
Year of Publication
2019
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Walls
Beams
Floors

Picture Frame and Diagonal Compression Testing of Cross-laminated Timber

https://research.thinkwood.com/en/permalink/catalogue2402
Year of Publication
2019
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Application
Walls
Wood Building Systems
Floors

Shear Modulus Analysis of Cross-Laminated Timber Using Picture Frame Tests and Finite Element Simulations

https://research.thinkwood.com/en/permalink/catalogue2692
Year of Publication
2020
Topic
Mechanical Properties
Material
CLT (Cross-Laminated Timber)
Author
Turesson, Jonas
Berg, Sven
Björnfot, Anders
Ekevad, Mats
Publisher
Springer
Year of Publication
2020
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Topic
Mechanical Properties
Keywords
Shear Modulus
Finite Element Simulation
Picture Frame Test
Research Status
Complete
Series
Materials and Structures
Summary
Determining the mechanical properties of cross-laminated timber (CLT) panels is an important issue. A property that is particularly important for CLT used as shear walls in buildings is the in-plane shear modulus. In this study, a method to determine the in-plane shear modulus of 3- and 5-layer CLT panels was developed based on picture frame tests and a correction factor evaluated from finite element simulations. The picture frame test is a biaxial test where a panel is simultaneously compressed and tensioned. Two different testing methods are simulated by finite elements: theoretical pure shear models as a reference cases and picture frame models to simulate the picture frame test setup. An equation for calculating the shear modulus from the measured shear stiffnesses in the picture frame tests is developed by comparisons between tests and finite element simulations of the CLT panels. The results show that pure shear conditions are achieved in the central region of the panels. No influence from the size of the tested panels is observed in the finite element simulations.
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11 records – page 1 of 2.