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21 records – page 2 of 3.

On the Lateral Stability of Multi-Story Mass-Timber Buildings Subjected to Tornado-Like Wind Field

https://research.thinkwood.com/en/permalink/catalogue1972
Year of Publication
2018
Topic
Wind
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Bezabeh, Matiyas
Gairola, Anant
Bitsuamlak, Girma
Tesfamariam, Solomon
Popovski, Marjan
Year of Publication
2018
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Wind
Design and Systems
Keywords
Mass Timber
Lateral Load Resisting Systems
Tornadoes
Dynamic
Wind Loading
Lateral Instability
Enhanced Fujita
Boundary Layer Flow
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
In this paper, we examined the effects of extreme tornadic wind loads on mass-timber buildings. In general, mass-timber buildings utilize pre-engineered wood panels to form their main gravity and lateral load resisting systems. The lightweight nature of timber makes these types of emerging buildings lighter and more flexible than buildings made from concrete, masonry or steel. In general, global lateral instability of buildings can occur when the overturning forces due to wind loads exceed the dead load of the structures. In the present study, wind loads were obtained from laboratory simulations of tornado-like wind field and atmospheric boundary layer flow at Western University, Canada. Tornado wind loads from the laboratory tests were scaled to five Enhanced Fujita wind speeds representing various levels of damage. Dynamic structural analyses were carried out to assess floor level demands. It is shown that extreme tornado wind loads may pose significant damage to mass-timber buildings designed for 1-in-50 wind speed using a load factor of 1.4. Based on the obtained results, design strategies are suggested for mass-timber buildings in tornado-prone areas.
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Reduced and test-data correlated FE-models of a large timber truss with dowel-type connections aimed for dynamic analyses at serviceability level

https://research.thinkwood.com/en/permalink/catalogue3004
Year of Publication
2022
Topic
Mechanical Properties
Serviceability
Acoustics and Vibration
Material
Glulam (Glue-Laminated Timber)
Application
Trusses
Author
Landel, Pierre
Linderholt, Andreas
Organization
RISE Research Institutes of Sweden
Linnaeus University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Application
Trusses
Topic
Mechanical Properties
Serviceability
Acoustics and Vibration
Keywords
Tall Timber Structures
Mechanical Connection
Dowel-type Fastener
Wind-induced Vibration
Modal Testing Properties
Connection Stiffness
FE-Model Reduction
Research Status
Complete
Series
Engineering Structures
Summary
The rise of wood buildings in the skylines of cities forces structural dynamic and timber experts to team up to solve one of the new civil-engineering challenges, namely comfort at the higher levels, in light weight buildings, with respect to wind-induced vibrations. Large laminated timber structures with mechanical joints are exposed to turbulent horizontal excitation with most of the wind energy blowing around the lowest resonance frequencies of 50 to 150 m tall buildings. Good knowledge of the spatial distribution of mass, stiffness and damping is needed to predict and mitigate the sway in lighter, flexible buildings. This paper presents vibration tests and reductions of a detailed FE-model of a truss with dowel-type connections leading to models that will be useful for structural engineers. The models also enable further investigations about the parameters of the slotted-in steel plates and dowels connections governing the dynamical response of timber trusses.
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Risk-Based Wind Design of Tall Mass-Timber Buildings

https://research.thinkwood.com/en/permalink/catalogue1970
Year of Publication
2018
Topic
Wind
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Bezabeh, Matiyas
Tesfamariam, Solomon
Bitsuamlak, Girma
Year of Publication
2018
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Wind
Keywords
Tall Wood
Tall Timber
Wind Loading
Fragility Curves
Dynamic Tests
Conference
The Canadian Society for Civil Engineers Annual Conference
Research Status
Complete
Summary
The rapid growth of urban population and the associated environmental concerns are partly influencing city planners and construction stakeholders to consider “Sustainable Urbanization” alternatives. In this regard, recent urban design strategies are entertaining the use of “tall timber buildings.” Generally, tall mass-timber buildings (MTBs) utilize pre-engineered wood panels to form their main gravity and lateral load resisting systems, which makes them lighter and more flexible than buildings made from concrete, masonry or steel. As a result, frequent exposure to excessive wind-induced vibrations can cause occupant discomfort and possible inhabitability of the buildings. This paper attempts to apply a risk-based procedure to design a 102-meter tall MTB by adapting and extending the Alan G. Davenport Wind Loading Chain as a probabilistic performance-based wind engineering framework. The structural systems of the study building are composed of Cross Laminated Timber (CLT) shear walls, CLT floors, glulam columns, and reinforced-concrete link beams. Initially, aerodynamic wind tunnel tests were carried out at the Boundary Layer Wind Tunnel Laboratory of Western University on the 1:200 scale MTB model to obtain transient wind loads. Subsequently, using the wind tunnel data, the study MTB was structurally designed. In the riskbased performance assessment, uncertainties were incorporated at each step of the Wind Loading Chain, i.e., local wind, exposure, aerodynamics, dynamic effects, and criteria. These uncertainties were explicitly modeled as random variables. Dynamic structural analyses were carried out in the frequency domain to include the amplification due to the resonance component of the excitation. Structural reliability analysis through Monte Carlo sampling was used to propagate the uncertainties through the Wind Loading Chain to quantify the risk of inhabitability and excessive deflection. The results of reliability analysis were used to develop fragility curves for wind vulnerability estimations. Based on the results, the effects of various uncertainties are discussed, and risk-based design decisions are forwarded.
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Scotia Place – 12 Story Apartment Building. A Case Study of High-Rise Construction Using Wood and Steel – WCTE2000

https://research.thinkwood.com/en/permalink/catalogue1852
Year of Publication
2018
Topic
Design and Systems
Acoustics and Vibration
Material
Glulam (Glue-Laminated Timber)
Other Materials
Application
Floors
Author
Moore, Mark
Publisher
New Zealand Timber Design Society
Year of Publication
2018
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Other Materials
Application
Floors
Topic
Design and Systems
Acoustics and Vibration
Keywords
Gravity Loads
Lateral Loads
Wind
Earthquake
Vibration
Acoustics
Moisture Content
Research Status
Complete
Series
New Zealand Timber Design Journal
Summary
This paper describes the design of a 12-story apartment building on a single story basement, which has wood floor diaphragms, and structural steel gravity and lateral load resisting systems. The design objective was to develop the most cost-effective structural system while meeting building functionality goals and adhering to code requirements. The main structural and non-structural design issues considered in this all-wood floor building are reviewed: gravity loads, lateral loads imposed by wind and earthquake, floor vibration, acoustics, and changes in wood moisture content. The lightweight structural form proved to be a practical system to lower construction material cost and enable alternative construction techniques to be employed. A comparison with a concrete floor option is briefly made.
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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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Tall Timber Buildings—A Preliminary Study of Wind-Induced Vibrations of a 22-Storey Building

https://research.thinkwood.com/en/permalink/catalogue2356
Year of Publication
2016
Topic
Wind
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Author
Johansson, Marie
Linderholt, Andreas
Jarnerö, Kirsi
Landel, Pierre
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Wood Building Systems
Topic
Wind
Keywords
Deflection
Dynamic Properties
Stabilisation
Sway
Wind Loads
Tall Timber
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
During the last years the interest in multi-storey timber buildings has increased and several medium-to high-rise buildings with light-weight timber structures have been designed and built. Examples of such are the 8-storey building “Limnologen” in Växjö, Sweden, the 9-storey “Stadthouse” in London, UK and the 14-storey building “Treet” in Bergen, Norway. The structures are all light-weight and flexible timber structures which raise questions regarding wind induced vibrations. This paper will present a finite element-model of a 22 storey building with a glulam-CLT structure. The model will be used to study the effect of different structural properties such as damping, mass and stiffness on the peak acceleration and will be compared to the ISO 10137 vibration criteria for human comfort. The results show that it is crucial to take wind-induced vibrations into account in the design of tall timber buildings.
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A theoretical study of the dynamic response of planar timber frames with semi-rigid moment-resisting connections subjected to wind loads

https://research.thinkwood.com/en/permalink/catalogue2960
Year of Publication
2021
Topic
Wind
Application
Frames
Author
Cao, Alex Sixie
Stamatopoulos, Haris
Organization
Norwegian University of Science and Technology
ETH Zurich
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Application
Frames
Topic
Wind
Keywords
Moment-resisting Timber Frames
Semi-rigid Connection
Wind-induced Vibrations
Time-domain Analysis
Frequency-domain Analysis
Serviceability
Tall Timber Buildings
Research Status
Complete
Series
Engineering Structures
Summary
The dynamic response of semi-rigid timber frames subjected to wind loads is investigated numerically in this paper. The dynamic response of more than one million unique frames with different parameters was assessed with the frequency-domain gust factor approach, which is currently adopted by Eurocode 1, and the time-domain generalized wind load method. In the generalized wind load method, the frames were simulated for three different wind velocities with five simulations per unique combination of parameters, resulting in more than twelve million simulations in total. Qualitative and quantitative observations of the dataset were made. Empirical expressions for the accelerations, displacements, and fundamental eigenfrequency were proposed by the use of nonlinear regression applied to the obtained numerical results and a frequency reduction factor was developed. The wind-induced accelerations obtained by the two methods were compared to the corresponding serviceability criteria according to ISO10137, providing insight about the feasibility of moment-resisting frames as a lateral load-carrying system for mid-rise timber buildings. Comparison between the theoretical gust factor approach and the generalized wind load method showed that the gust factor approach was nonconservative in most cases. Finally, the effect of uniform and non-uniform mass distributions was investigated, with a theoretical reduction in top-floor accelerations of 50% and 25% respectively.
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Wind and Earthquake Design Framework for Tall Wood-Concrete Hybrid System

https://research.thinkwood.com/en/permalink/catalogue2143
Year of Publication
2019
Topic
Seismic
Wind
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Tesfamariam, Solomon
Bezabeh, Matiyas
Skandalos, Konstantinos
Martinez, Edel
Dires, Selamawit
Bitsuamlak, Girma
Goda, Katsuichiro
Year of Publication
2019
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Seismic
Wind
Keywords
Tall Wood
Seismic design factors
Wind tunnel test
Ductility Factors
Timber-reinforced concrete
Force Modification Factors
Probabilistic Model
Wind Load
Overstrength seismic force
Research Status
Complete
Notes
DOI 10.14288/1.0380777
Summary
Advancement in engineered wood products altered the existing building height limitations and enhanced wooden structural members that are available on the market. These coupled with the need for a sustainable and green solution to address the ever-growing urbanization demand, avails wood as possible candidate for primary structural material in the construction industry. To this end, several researches carried out in the past decade to come up with sound structural solutions using a timber based structural system. Green and Karsh (2012) introduced the FFTT system; Tesfamariam et al. (2015) developed force-based design guideline for steel infilled with CLT shear walls, and SOM (2013) introduced the concrete jointed mass timber hybrid structural concepts. In this research, the basic structural concepts proposed by SOM (2013) is adopted. The objective of this research is to develop a wind and earthquake design guideline for concrete jointed tall mass timber buildings in scope from 10- to 40-storey office or residential buildings. The specific objective of this research is as follow: 1. Wind serviceability design guideline for hybrid mass-timber structures. 2. Calibration of design wind load factors for the serviceability wind design of hybrid tall mass timber structures. 3. Guidelines to perform probabilistic modeling, reliability assessment, and wind load factor calibration. 4. Overstrength related modification factor Ro and ductility related modification factor Rd for future implementation in the NBCC. 5. Force-based design guideline following the capacity based design principles.
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Wind Dynamics of the Next Generation of Tall Timber Buildings

https://research.thinkwood.com/en/permalink/catalogue3126
Year of Publication
2021
Topic
Wind
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Fryer, Bridget Kathryn
Organization
University of Cambridge
Year of Publication
2021
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Wind
Keywords
Wind Dynamics
Tall Buildings
Tall Timber Buildings
Skyscrapers
Research Status
Complete
Summary
Despite all being less than 100 metres tall, the world's tallest timber buildings all utilise concrete to increase their mass such that they do not vibrate excessively under wind loading. Wind-induced vibrations must be minimised to ensure that the building's occupants remain comfortable and do not regularly experience motion sickness during high winds. Despite the difficulties with wind dynamics for the current generation of timber towers, numerous concept designs have been announced that propose to build much taller with timber. However, at present, there has been little consideration of how the architecture of timber towers can be suitably designed to help combat the problem. This thesis investigates the effects of different structural typologies on the dynamic performance of timber buildings by studying four iconic skyscrapers; the Gherkin, the Shard, the John Hancock Center and 432 Park Avenue and examining how they would perform if built from timber. First, they are assessed at their existing heights and across a range of shorter heights, with their steel or concrete frames but examining the effect of replacing their concrete floors with CLT. Secondly (and again across a range of heights), the buildings are redesigned with a timber frame to test how their dynamics would change if their steel or concrete beams, columns and walls were replaced with glulam sections and CLT panels. The Shard and 432 Park Avenue, which have concrete cores, have also been examined to see how they perform if they kept their concrete cores, but if the remainder of their structures were built from timber. In total, 144 combinations of building, floor material, height, and frame material are assessed. Retaining their existing steel or concrete frames but replacing their concrete floors with CLT resulted in the buildings' natural frequencies increasing by an average of 30% and the peak accelerations by 47%. These changes are due to the CLT floors being considerably lighter than the original concrete floors. By comparison, the change from a steel or concrete-framed structure to a timber-framed structure (with no change in floor type) made little difference to the peak accelerations, but caused natural frequencies to increase by 11%. If their existing structures were retained, but CLT panels with a thin layer of concrete screed were used for their floors (instead of deep concrete slabs), then the Gherkin at 182 m, the Shard at 200 m, the John Hancock Center at 196 m and 432 Park Avenue at 137 m would have acceptable vibrations (for residential occupancy) if located in a low wind speed environment like London. Across the four buildings, this change in floor type would save an average of 24 kgCO2 per m2 of floorspace if sequestered carbon is excluded, and 170 kgCO2/m2 if sequestered carbon is included. When sequestered carbon is included in the calculation, the net carbon stored in CLT is enough to offset the embodied carbon of the steel and concrete of the Shard (at 200 m) and 432 Park Avenue (at 137 m). When sizing the columns and diagonals of the Gherkin and the John Hancock Center, the strength criteria was the limiting factor (rather than stiffness). This is because both towers have well-braced tubular designs that are inherently stiff, thanks to the majority of their columns and diagonals being located on their perimeters. With strength as the governing criterion, the size of the structural members could be reduced when lightweight CLT floors were used instead of concrete. For example, the columns of the Gherkin would have required 32% less steel if CLT floors had been used instead of concrete decks. Such savings would not be possible for the Shard or 432 Park Avenue, where the stiffness criterion limits the sizes of the sections. If the four skyscraper designs were built with a timber frame, the Gherkin would comfortably be the best performing structure thanks to its inherently stiff diagrid shell and its circular cross-section. It could easily satisfy the ISO 10137 human comfort criterion for residential occupancy in most locations at its full height of 182 metres. Taller versions of the structure are also likely to be viable. If built in London, a fully-timber Shard at 134 m (or 200 m with a concrete core and glulam frame), a timber John Hancock Center at 196 m, and a fully timber 432 Park Avenue at 80 m (or a hybrid at 137 m) could also satisfy the same criterion (all with CLT and screed floors). Across a set of the 135 m versions of the four skyscrapers, the change from a steel or concrete frame to a glulam and CLT structure would result in a saving of 130 kgCO2/m2 (including sequestered carbon) or a saving of 92 kgCO2/m2 for a hybrid (timber beams and columns, but retaining a concrete core). Overall, when different typologies were compared on a like-for-like basis, braced tubular forms like the Gherkin and the John Hancock Center worked the best in timber, producing lower wind-induced vibrations than 432 Park Avenue and the Shard. Furthermore, their tubular structures required smaller column sizes (which occupy a lower percentage of their floor space), have lower material costs per m2 of floor space and would result in less embodied carbon per m2 (if sequestered carbon is ignored) than those which rely on an internal core for lateral stability. The next generation of tall timber buildings looks unlikely to reach some of the super tall heights proposed without significant additional damping, added mass or suitable aerodynamic cross-sections that can minimise wind-induced vibrations. However, this thesis has shown that timber does have the potential to be used in suitably designed tall buildings up to at least 200 m tall, without additional damping or mass, and as the primary structural material in the frame or as an alternative to concrete floors.
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Wind-Induced Dynamic Response of a 22-Storey Timber Building: Options for Structural Design of the Hallonbergen Project

https://research.thinkwood.com/en/permalink/catalogue64
Year of Publication
2015
Topic
Design and Systems
Wind
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Tjernberg, Frida
Organization
KTH royal institute of technology
Year of Publication
2015
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Design and Systems
Wind
Keywords
Residential
Tall Wood
Wind Load
High-Rise
Research Status
Complete
Summary
Folkhem is a Swedish company exclusively building timber residential buildings in the Stockholm area. The company is currently in the planning stages of what would be the world’s tallest timber building, a 22-storey timber residential buiding in Hallonbergen, Sundbyberg. In this master thesis, this proposed building has been analyzed with regards to its wind-induced dynamic response. The work includes studies of stabilization of tall structures, case studies of existing buildings and developed systems for tall timber construction and analyzed options for structural design of the Hallonbergen project. Eleven different structural systems have been investigated with regards to their displacement at the top and their peak acceleration when subject to wind loading. The peak acceleration has been calculated using both Eurocode and ISO 4354. The values have been assessed against ISO 6897 and ISO 10137. The results indicate that it is possible to construct the Hallonbergen project without risk of unacceptable dynamic response, using any of the following options: The Martinson’s system with 259 mm CLT plates The Kauffmann system The structural system presented in “The Case for Tall Wood Buildings” The structural system presented in “The Timber Tower Research Project”
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21 records – page 2 of 3.