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Evaluation of Timber-Concrete Floor Performance under Occupant-Induced Vibrations using Continuous Monitoring

https://research.thinkwood.com/en/permalink/catalogue131
Year of Publication
2013
Topic
Acoustics and Vibration
Serviceability
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Floors
Author
Omenzetter, Piotr
Kohli, Varun
Desgeorges, Yohann
Publisher
Scientific.net
Year of Publication
2013
Country of Publication
Switzerland
Format
Journal Article
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Floors
Topic
Acoustics and Vibration
Serviceability
Keywords
Damping
Frequencies
Lightweight
Long Span
Office Buildings
Language
English
Research Status
Complete
Series
Key Engineering Materials
Summary
This paper describes the design of a system to monitor floor vibrations in an office building and an analysis of several months worth of collected data. Floors of modern office buildings are prone to occupant-induced vibrations. The contributing factors include long spans, slender and flexible designs, use of lightweight materials and low damping. As a result, resonant frequencies often fall in the range easily excited by normal footfall loading, creating potential serviceability problems due to undesirable levels of vibrations. This study investigates in-situ performance of a non-composite timber-concrete floor located in a recently constructed innovative multi-storey office building. The floor monitoring system consists of several displacement transducers to measure long-term deformations due to timber and concrete creep and three accelerometers to measure responses to walking forces, the latter being the focus of this paper. Floor response is typically complex and multimodal and the optimal accelerometer locations were decided with the help of the effective independence-driving point residue (EfI-DPR) technique. A novel approach to the EfI-DPR method proposed here uses a combinatorial search algorithm that increases the chances of obtaining the globally optimal solution. Several months worth of data collected by the monitoring system were analyzed using available industry guidelines, including ISO2631-1:1997(E), ISO10137:2007(E) and SCI Publication P354. This enabled the evaluation of the floor performance under real operating conditions.
Online Access
Free
Resource Link
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Modal Vibration Testing of an Innovative Timber Structure

https://research.thinkwood.com/en/permalink/catalogue1494
Year of Publication
2016
Topic
Acoustics and Vibration
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Hybrid Building Systems
Author
Leyder, Claude
Frangi, Andrea
Chatzi, Eleni
Year of Publication
2016
Country of Publication
Austria
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Timber-Concrete Composite
Application
Hybrid Building Systems
Topic
Acoustics and Vibration
Keywords
Beech
Post-Tensioned
Modal Vibration Tests
Eigenfrequencies
Damping Ratios
Mode Shapes
Language
English
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 177-185
Summary
This research paper deals with the evaluation of the dynamic modal vibration tests conducted on an innovative timber structure, the ETH House of Natural Resources. The building serves as a demonstrator of several innovative structural systems and technologies relating to timber. The main load-bearing structure comprises a posttensioned timber frame, which was subjected to modal vibration tests, firstly in the laboratory and, subsequently on the construction site. In this paper, the modal characteristics (eigenfrequencies, damping ratios and mode shapes), obtained from the laboratory testing campaign are presented. The modal vibration data is evaluated using polynomial and subspace identification techniques. The obtained results reveal that the structure exhibits pure translational, beam and column modes, as well as mixed beam-column modes. The bottom connection of the columns delivers significant influence on the modal characteristics, whereas the level of post-tensioning force yields no substantial influence in the modal characteristics obtained from low amplitude modal vibration tests.
Online Access
Free
Resource Link
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Study to Validate the Floor Vibration Design of a New Mass Timber Building

https://research.thinkwood.com/en/permalink/catalogue2634
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Organization
KPFF
Country of Publication
United States
Material
CLT (Cross-Laminated Timber)
Timber-Concrete Composite
Application
Floors
Topic
Acoustics and Vibration
Keywords
Vibration Performance
Damping
Span Length
Prediction
Research Status
In Progress
Notes
Project contact is Jacob McCann at KPFF
Summary
As interest has grown in using mass timber for commercial building projects, so too has the need to better understand the vibration characteristics of mass timber floor systems. Vibration requirements typically drive the spans and thicknesses of mass timber floors. Our team has a unique opportunity to close several crucial knowledge gaps while designing the new Health Sciences Education Building (HSEB) at the University of Washington, which is under design and is scheduled to start construction in the summer of 2019. Case Study for Design Guide – The HSEB will be designed using the U.S. Mass Timber Floor Vibration Design Guide. Vibration performance will be measured to further validate or refine the model calibration suggestions put forth in the Design Guide. Damping Measurements – The HSEB will contain a wide variety of program spaces with varying damping characteristics that will be measured and correlated. Stiffness Measurements – Laboratory and in situ testing will be performed on a several floor framing systems. This will include a variety of span lengths and member depths. It will also include composite behavior of concrete and CLT floors with different connection types. The results of this study will allow for more accurate predictions of floor vibrations. This will significantly reduce the cost of mass timber systems in way that is repeatable and scalable for future architects and engineers.
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