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10 records – page 1 of 1.

The 200 m timber tower - A study on the possibilities of constructing a 200 meter tall timber building

https://research.thinkwood.com/en/permalink/catalogue3127
Year of Publication
2020
Topic
Wind
Application
Wood Building Systems
Author
Gyllensten, Sebastian
Modig, Axel
Organization
Chalmers University of Technology
Year of Publication
2020
Format
Thesis
Application
Wood Building Systems
Topic
Wind
Keywords
Aerodynamics
Tall Timber Structure
Wind Load
Acceleration
Research Status
Complete
Summary
As the interest in timber buildings is increasing, more attention is pointed towards highrise timber buildings. Partly because it is one of the main areas pushing the development within the field of timber structures. As the current tallest timber building, Mjöstornet in Brumunddal is approximately 10 times shorter than the world’s tallest building, Burj Khalifa, the intuition says that there is room for major improvements regarding tall timber structures. The aim of this thesis is therefore to investigate the possibilities to build a 200 m tall timber tower while still fulfilling the requirements for strength, stability and dynamics. In order to anchor the project in reality, the assumed building location is Gothenburg with the ground conditions of solid rock. Early in the study it was concluded that in order to push the height limits, the building design had to be improved compared to the existing timber buildings. The main geometries of interest turned out to be the circular shape thanks to its aerodynamical benefits. This base shape was applied in various ways, generating five different concepts ready for evaluation. Each of the five concepts were modelled and preliminary sized using Grasshopper and Karamba 3D, whereafter they were evaluated based on their dynamic performance, global stiffness, and a few other evaluation criteria. The evaluation was primary made with structural performance in mind and secondary with regard to comfort, quality and economical aspects. The results show that one of the concepts have great potential of reaching 200 m despite the uncertainties regarding joint stiffness and structural damping. Also, a few of the other concepts might be able to reach 200 m if subject to some structural and dynamical improvements.
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Acoustic performance of junctions in cross laminated timber constructions

https://research.thinkwood.com/en/permalink/catalogue3097
Year of Publication
2019
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Author
Hörnmark, Jesper
Organization
Chalmers University of Technology
Year of Publication
2019
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Topic
Acoustics and Vibration
Keywords
Mass Timber
Vibration Reduction Index
Flanking Transmission
Research Status
Complete
Summary
With the emergence of cross laminated timber (CLT) as a structural material on the global market, the need to understand the acoustical behavior of buildings constructed with the material grows. CLT faces a set of challenges that concrete or masonry do not; being low density, high in stiffness, sometimes isotropic and sometimes orthotropic depending on the composition. Flanking sound transmission often becomes an issue in the acoustic performance of mass timber buildings. While direct sound transmission can be treated with conventional methods e.g. additional layers, the flanking paths are more complicated to treat since they need to transfer loads over the length of the element. This master’s thesis aims to investigate the flanking paths in cross laminated timber buildings by measuring the structure-borne vibration reduction index (Kij) in realized buildings. The in-field measurements are compared to standardized estimation models and lab measurements published in past research. This thesis finds that standardized estimations underestimate the performance of the examined junctions in low frequencies. The lab measurements are closer to the in-field performance but exaggerate the influence of metal connections and mass-spring behavior of junctions with elastic interlayers. Additionally the theory and results indicates that external loads on the junction play a major role in the resulting performance. Elastic interlayers are not as effective in low levels as in the high levels of any given building, presenting a challenge as mass timber structures are increasingly being built taller.
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Assessment and Optimisation of CFRP Reinforced Glulam Beams - A Feasibility Study in Design Stage Reinforcement Configurations for Pedestrian Bridge Applications

https://research.thinkwood.com/en/permalink/catalogue2458
Year of Publication
2019
Topic
Mechanical Properties
Material
Glulam (Glue-Laminated Timber)
Application
Bridges and Spans

Designing Pedestrian Stress-Laminated Timber Bridges for Multiple Spans: Parameters Related to Dynamic Response

https://research.thinkwood.com/en/permalink/catalogue2576
Year of Publication
2019
Topic
Design and Systems
Application
Bridges and Spans

Designing timber connections for ductility – A review and discussion

https://research.thinkwood.com/en/permalink/catalogue2949
Year of Publication
2021
Topic
Connections
Application
Wood Building Systems
Author
Ottenhaus, Lisa-Mareike
Jockwer, Robert
Drimmelen, David
Crews, Keith
Organization
The University of Queensland
Chalmers University of Technology
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Application
Wood Building Systems
Topic
Connections
Keywords
Ductility
Design Codes
Performance-based Design
Research Status
Complete
Series
Construction and Building Materials
Summary
This paper discusses the design principles of timber connections for ductility with focus on laterally-loaded dowel-type fasteners. Timber connections are critical components of timber structures: not only do they join members, but they also affect load capacity, stiffness, and ductility of the overall system. Moreover, due to the brittle failure behaviour of timber when loaded in tension or shear, they are often the only source of ductility and energy dissipation in the structure in case of overloading, much like a fuse in an electrical circuit. This paper addresses current challenges in connection design for ductility, reviews selected best-practice design approaches to ensure ductility in timber connections, suggests simple performance-based design criteria to design connections for ductility, and aims to stimulate a discussion around potential solutions to implement safe design principles for ductile connections in future design codes and connection testing regimes.
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Dynamic Response in Tall Timber Structures

https://research.thinkwood.com/en/permalink/catalogue3098
Year of Publication
2018
Topic
Acoustics and Vibration
Application
Wood Building Systems
Author
Fredrik, Ivarsson
Joel, Sjöholm
Organization
Chalmers University of Technology
Year of Publication
2018
Format
Thesis
Application
Wood Building Systems
Topic
Acoustics and Vibration
Keywords
Multi Storey Structure
Wind Load
Acceleration
Research Status
Complete
Summary
Modern building tend to strive towards more slender and lightweight constructions. That is to be more provident with space and materials as well as for aesthetic reasons. The effect of these lightweight slender buildings is an increased sensitivity to lateral loads with regard to the dynamic behaviour of the structure. Since the european union changed to more function based standards, the development of timber and timber products have increased during the past 20 years. It is now both in the interest of and feasible to build taller and larger buildings with the primary load bearing system made of timber. Timber have a relatively low mass compared to other construction materials which can result in larger deformations and discomfort if the dynamic response in the structure is too large. The purpose of this report is to make a parametric study on how mass, stiffness and damping affect the feasible building height of a tall timber structure with regard to dynamic effects caused by wind. This is performed via simulations and analyses of a planned timber structure above 10 floors. The general design parameters are modified in order to fulfill the acceleration requirements for a structure with an increasing number of floors. The initial structure is composed of load bearing Cross Laminated Timber (CLT) walls and floors that acts in diaphragm action. A FE-model is used to determine the eigenfrequencies of the structure and the swedish Annex, EKS 10, is used to calculate the peak acceleration. The determined eigenfrequency and acceleration curve is compared with the requirements of horizontal acceleration according to ISO 10137. If the structure fulfills the requirements, the structure is successively increased with 2 storeys at the time. If the structure does not fulfill the demands, it is improved with mass, stiffness and/or damping in an iteration process until it fulfills the requirements. The result of this study is divided into a "general behaviour" and a "structural behaviour" chapter, to make it possible to understand the impact of each individual parameter separately and the combined impact on the structure. The improvements of adding mass and stiffness separately did not result in dramatic improvements of the acceleration. But by combining mass, damping and stiffness, considerable improvements with respect to the dynamic response is achieved and a building height of 26 storeys was feasible. Improvements of mass and damping combined made it possible to fulfill the demands on a 22 storey timber structure. This study conclude that the most feasible solution is to add mass and damping in forms of a concrete top storey (floor and walls) together with a TMD (Tuned Mass Damper) on the top floor.
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A holistic framework for designing for structural robustness in tall timber buildings

https://research.thinkwood.com/en/permalink/catalogue2853
Year of Publication
2021
Topic
Design and Systems
Material
Other Materials
Application
Wood Building Systems
Author
Voulpiotis, Konstantinos
Köhler, Jochen
Jockwer, Robert
Frangi, Andrea
Organization
ETH Zurich
National Technical University of Norway
Chalmers University of Technology
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
Other Materials
Application
Wood Building Systems
Topic
Design and Systems
Keywords
Robustness
Tall Timber Buildings
Disproportionate Collapse
Reliability
System Effects
Research Status
Complete
Series
Engineering Structures
Summary
With the ever-increasing popularity of engineered wood products, larger and more complex structures made of timber have been built, such as new tall timber buildings of unprecedented height. Designing for structural robustness in tall timber buildings is still not well understood due the complex properties of timber and the difficulty in testing large assemblies, making the prediction of tall timber building behaviour under damage very difficult. This paper discusses briefly the existing state-of-the-art and suggests the next step in considering robustness holistically. Qualitatively, this is done by introducing the concept of scale, that is to consider robustness at multiple levels within a structure: in the whole structure, compartments, components, connections, connectors, and material. Additionally, considering both local and global exposures is key in coming up with a sound conceptual design. Quantitatively, the method to calculate the robustness index in a building is presented. A novel framework to quantify robustness and find the optimal structural solution is presented, based on the calculation of the scenario probability-weighted average robustness indices of various design options of a building. A case study example is also presented in the end.
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Long-term deformation behaviour of timber columns: Monitoring of a tall timber building in Switzerland

https://research.thinkwood.com/en/permalink/catalogue2881
Year of Publication
2021
Topic
Serviceability
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Columns
Author
Jockwer, Robert
Grönquist, Philippe
Frangi, Andrea
Organization
Chalmers University of Technology
ETH Zurich
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
LVL (Laminated Veneer Lumber)
Application
Columns
Topic
Serviceability
Keywords
Creep
Rheological Material Behaviour
Long-term Behaviour
Research Status
Complete
Series
Engineering Structures
Summary
Knowledge on the short and long term deformation behavior of highly loaded components in tall timber buildings is important in view of improving future design possibilities with respect to serviceability, both in the construction and in the operational state. In this paper, we present the results of a monitoring case-study on a tall timber-hybrid building in Switzerland, a 15 storey and 60 m high office building completed in 2019. A fibre-optic measuring system showed an increase of the deformation with increasing load during the construction phase of highly stressed spruce-GLT and beech-LVL columns. However, the highest strain values were not reported in the columns themselves but at the ceiling transitions and in the area near their supports. The measurements on the columns were compared with model calculations for long-term deformation of timber elements in order to differentiate single components of the total deformation caused by load, time, and changes in climate during the construction. Over a monitoring period of a year, good agreement of the modelled deformations could be confirmed, which indicates that such models could be well suited for future usage in serviceability design of tall timber buildings.
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Risk Assessment Framework to Avoid Serial Failure for New Technical Solutions Applied to the Construction of a CLT Structure Resilient to Climate

https://research.thinkwood.com/en/permalink/catalogue2893
Year of Publication
2021
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Tengberg, Charlotte
Hagentoft, Carl-Eric
Organization
Chalmers University of Technology
Editor
Lacasse, Michael
Publisher
MDPI
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Keywords
Risk Assessment
Serial Failure
Moisture
Mold
New Technical Solutions
Research Status
Complete
Series
Buildings
Summary
Design-build contractors are challenged with the task of minimizing failure risks when introducing new technical solutions or adapting technical solutions to new conditions, e.g., climate change. They seem to have a disproportional trust in suppliers and their reference cases and might not have adequate resources or methodologies for sufficient evaluation. This creates the potential for serial failures to spread in the construction industry. To mitigate this, it was suggested that a predefined risk assessment framework should be introduced with the aim of providing a prequalification and requirements for the use of the technical solution. The objectives of this paper are to develop a comprehensive risk assessment framework and to explore the framework’s potential to adequately support the design-build contractor’s decisions. The framework uses qualitative assessment, relying on expert workshops and quantitative assessments, with a focus on simulation and probabilities. Tollgates are used to communicate risk assessments to the contractor. The framework is applied to a real-life case study of construction with a CLT-structure for a Swedish design-build contractor, where exposure to precipitation during construction is a key issue. In conclusion, the chosen framework was successful in a design-build contractor context, structuring the process and identifying difficulties in achieving the functional requirements concerning moisture. Three success factors were: documentation and communication, expert involvement, and the use of tollgates. Recommendations to the design-build contractor on construction of CLT structure are to keep construction period short and to use full weather protection on site.
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Stability and Dynamic Properties of Tall Timber Structures - A parametric study of the structural response due to wind action

https://research.thinkwood.com/en/permalink/catalogue3096
Year of Publication
2019
Topic
Wind
Author
Alalwan, Ahmad
Larsson, Joakim
Organization
Chalmers University of Technology
Year of Publication
2019
Format
Thesis
Topic
Wind
Keywords
Dynamic Response
Human Occupancy
Tall Timber Structure
Wind-induced Vibration
Research Status
Complete
Summary
The interest in building taller structures in timber is increasing in the building sector. However, the high strength-to-weight ratio of timber leads to a relatively light structure which is often associated with vibrations. The dynamic properties are essential in the design of tall timber structures, where wind-induced vibrations of the building in service state is addressed. The dynamic response is influenced by mass, stiffness and damping. These parameters influence the acceleration of the building which can be perceived as a discomfort for human occupancy. The aim is to find a structural concept that makes a taller structure than the usual today feasible. The objective is to make a parametric study and investigate how a multi-storey residential building of timber can be optimized with respect to dynamic wind loading. With a combination of numerical and analytical methods, accelerations are calculated and evaluated against the criteria for human comfort according to ISO 10137 and ISO 6897. An analytical calculation sheet is set up according to SS-EN-1991-1-4 and EKS 10 to define wind-induced acceleration. Starting from a beam-column structure with a central core, the effect of adding inner walls and exterior bracing is studied to see what limits the number of storeys for an open plan building. Analysis of the dynamic response due to wind shows the fundamental mode shape in torsion before exterior bracing is added. Results have shown that the structure can reach 5-storeys with inner walls of cross-laminated timber and 4-storeys with no walls. Moreover, it’s found that diagonal bracing in the facades improves the torsional stiffness significantly and the fundamental mode becomes a transversal mode. An outrigger bracing system has been found to be the most efficient, leading to a structure of 12-storeys. The parameters mass and stiffness are modified by adding concrete floors and assigning larger sections to the structure. Results show that the building can achieve 15-storeys with pure timber and 21-storeys when concrete floors are added. Secondary parametric action i.e. adding another outrigger generates a gain of one-storey and modifying the truss-work to steel gives a structure of 23-storeys.
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10 records – page 1 of 1.