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Ambient and Forced Vibration Testing and Finite Element Model Updating of a Full-Scale Posttensioned Laminated Veneer Lumber Building

https://research.thinkwood.com/en/permalink/catalogue1103
Year of Publication
2012
Topic
Seismic
Wind
Acoustics and Vibration
Material
LVL (Laminated Veneer Lumber)
Application
Wood Building Systems
Shear Walls
Author
Worth, Margaret
Omenzetter, Piotr
Morris, Hugh
Year of Publication
2012
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
Application
Wood Building Systems
Shear Walls
Topic
Seismic
Wind
Acoustics and Vibration
Keywords
Post-Tensioned
Full Scale
In Situ
Finite Element Model
Dynamic Performance
Conference
New Zealand Society for Earthquake Engineering Conference
Research Status
Complete
Notes
April 13-15, 2012, Christchurch, New Zealand
Summary
The Nelson Marlborough Institute of Technology Arts and Media building was completed in 2011 and consists of three seismically separate complexes. This research focussed on the Arts building as it showcases the use of coupled post-tensioned timber shear walls. These are part of the innovative Expan system. Full-scale, in-situ dynamic testing of the novel building was combined with finite element modelling and updating to obtain an understanding of the structural dynamic performance within the linear range. Ambient testing was performed at three stages during construction and was combined with forced vibration testing for the final stage. This forms part of a larger instrumentation program developed to investigate the wind and seismic response and long term deformations of the building. A finite element model of the building was formulated and updated using experimental modal characteristics. It was shown that the addition of non-structural elements, such as cladding and the staircase, increased the natural frequency of the first mode and the second mode by 19% and 24%, respectively. The addition of the concrete floor topping as a structural diaphragm significantly increased the natural frequency of the first mode but not the second mode, with an increase of 123% and 18%, respectively. The elastic damping of the NMIT building at low-level vibrations was identified as being between 1.6% and 2.4%
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Ambient Vibration Tests of a Cross-Laminated Timber Building

https://research.thinkwood.com/en/permalink/catalogue313
Year of Publication
2015
Topic
Wind
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Shear Walls
Author
Reynolds, Thomas
Harris, Richard
Chang, Wen-Shao
Bregulla, Julie
Bawcombe, Jonathan
Publisher
ICE Publishing
Year of Publication
2015
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Shear Walls
Topic
Wind
Keywords
Damping
Dynamic Movement
In Situ
Multi-Storey
Stiffness
Modal Properties
Ambient Vibration Method
Research Status
Complete
Series
Proceedings of the Institution of Civil Engineers - Construction Materials
Summary
Cross-laminated timber has, in the last 6 years, been used for the first time to form shear walls and cores in multi-storey buildings of seven storeys or more. Such buildings can have low mass in comparison to conventional structural forms. This low mass means that, as cross-laminated timber is used for taller buildings still, their dynamic movement under wind load is likely to be a key design parameter. An understanding of dynamic lateral stiffness and damping, which has so far been insufficiently researched, will be vital to the effective design for wind-induced vibration. In this study, an ambient vibration method is used to identify the dynamic properties of a seven-storey cross-laminated timber building in situ. The random decrement method is used, along with the Ibrahim time domain method, to extract the modal properties of the structure from the acceleration measured under ambient conditions. The results show that this output-only modal analysis method can be used to extract modal information from such a building, and that information is compared with a simple structural model. Measurements on two occasions during construction show the effect of non-structural elements on the modal properties of the structure.
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Effect of Flexible Supports on Vibration Performance of Timber Floors

https://research.thinkwood.com/en/permalink/catalogue190
Year of Publication
2012
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Floors
Author
Jarnerö, Kirsi
Bolmsvik, Åsa
Brandt, Anders
Olsson, Anders
Organization
Euronoise
Year of Publication
2012
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Residential
Multi-Storey
Noise
Prefabrication
In Situ
Vibration
Damping
Interlayer
Conference
Ninth European Conference on Noise Control (Euronoise)
Research Status
Complete
Notes
June 10-13, 2012, Prague, Czech Republic
Summary
In residential multi-storey buildings of timber it is of great importance to reduce the flanking transmission of noise. Some building systems do this by installing a vibration-damping elastic interlayer, Sylomer or Sylodyn , in the junction between the support and the floor structure. This interlayer also improves the floor vibration performance by adding damping to the structure. In the present work the vibration performance of a floor with such interlayers has been investigated both in laboratory and field tests. A prefabricated timber floor element was tested in laboratory on rigid supports and on supports with four different types of interlayers. The results are compared with in situ tests on a copy of the same floor element. The effect on vibration performance i.e. frequencies, damping ratio and mode shapes is studied. A comparison of the in situ test and the test with elastic interlayer in laboratory shows that the damping in situ is approximately three times higher than on a single floor element in the lab. This indicates that the damping in situ is affected be the surrounding building structure. The achieved damping ratio is highly dependent on the mode shapes. Mode shapes that have high mode shape coefficients along the edges where the interlayer material is located, result in higher modal damping ratios. The impulse velocity response, that is used to evaluate the vibration performance and rate experienced annoyance in the design of wooden joist floors, seems to be reduced when adding elastic layers at the supports.
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Guidelines Definition for In-Situ Vibration Measurements of Buildings

https://research.thinkwood.com/en/permalink/catalogue1980
Year of Publication
2018
Topic
Acoustics and Vibration
Material
Timber-Concrete Composite
Application
Floors
Author
Lanata, Francesca
Boudaud, Clément
Amouzou, Kodzo Vioto
Year of Publication
2018
Format
Conference Paper
Material
Timber-Concrete Composite
Application
Floors
Topic
Acoustics and Vibration
Keywords
Vibrations
TCC
Guidelines Definition
Users' Comfort
In-Situ Measurements
Conference
World Conference on Timber Engineering
Research Status
Complete
Summary
As an attempt to find a correlation between dynamic response of timber and timber-concrete composite floors and users’ comfort feeling, an in-situ measurements campaign will be carried out within the framework of a research project started at ESB, France. A large variability of buildings typology, as multi-unit housing, open-space offices and long-span offices with partition walls will be tested. The first experimental experience has shown that choices of means of excitation, type and positioning of sensors, data acquisition device, data analyses methods, depend on the floor configuration. Using in-situ test campaign as a database to compare different measurement protocols and assess the influence of different in-situ conditions, the paper will propose some guidelines for the measurement architecture, the equipment choice and the data analysis to be performed according to each building configuration.
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Improving the Sound Absorption of Cross-Laminated Timber Panels Using Resonant Absorbent Layer

https://research.thinkwood.com/en/permalink/catalogue1265
Year of Publication
2017
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Rooms
Author
Logawa, Banda
Organization
University of British Columbia
Year of Publication
2017
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Rooms
Topic
Acoustics and Vibration
Keywords
Sound Absorption
In Situ
Reverberation Time
Speech Intelligibility Index
Research Status
Complete
Summary
Developed in the mid-1990s in Austria and Germany, Cross Laminated Timber (CLT) is an innovative wood product known for its strength in both orthogonal directions, and its dimensional stability, making it a sustainable alternative to concrete slabs. CLT is created through the cross-lamination process, which glues together odd number of layers of wood planks placed in orthogonally alternating directions. With the growing interest in the application of CLT in North America, numerous studies has been conducted to characterize the acoustical properties of CLT panels. However, most of them focused on the sound-transmission aspect of CLT, very few on the sound absorption. This thesis will explore the sound-absorption characteristics of CLT, the effect on overall room-acoustical conditions, the utilization of resonant sound-absorbing layers on CLT to make it more sound-absorptive, and proposed solutions to improve this performance aspect. To demonstrate the low sound absorption and poor acoustical conditions in rooms with exposed and untreated CLT panels, several in-situ reverberation-time (RT) measurements were conducted in multiple buildings in British Columbia. Average sound-absorption coefficients and estimated Speech Intelligibility Indices (SII) were calculated as baseline performance measures for this study. Based on the results from five different buildings, involving 8 rooms configurations, average sound-absorption coefficients for exposed CLT panels are approximately between 0.02 to 0.13, resulting in barely acceptable conditions for verbal communication. To optimize the sound-absorption characteristics of prototype CLT panels, a transfer-matrix model has been developed to predict the performance of multi-layered CLT panels. This theoretical model was then validated by using three different sound-absorption measurement methods (impedance tube, spherical decoupling, and reverberation chamber) for multiple HR array configurations. After identifying the important parameters of an HR system and their effects on performance, a final prototype configuration with Helmholtz Resonator Array was then created with the goal of improving the room- acoustical performance of CLT, as well as responding to input from the CLT manufacturers and experts. Both the theoretical and experimental results confirmed that the proposed solution has the required sound-absorption performance and achieves all research objectives.
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Obstacles Preventing the Off-Site Prefabrication of Timber and MEP Services: Qualitative Analyses from Builders and Suppliers in Australia

https://research.thinkwood.com/en/permalink/catalogue3160
Year of Publication
2022
Topic
General Information
Author
Lopez, Robert
Chong, Heap-Yih
Pereira, Conrad
Organization
Curtin University
Nanjing Audit University
Editor
Santos, Paulo
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Topic
General Information
Keywords
Construction
Collaboration
Coordination
MEP
Off-site
On-Site
In Situ
Prefabrication
Builder
Supplier
Australia
Research Status
Complete
Series
Buildings
Summary
Limited empirical and qualitative studies focus on the detailed processes and obstacles for coordinating off-site prefabrication between builders and suppliers. This research aims to identify and address the obstacles that currently prevent the further expansion of off-site prefabrication, with a research scope on timber and mechanical/electrical/plumbing (MEP) services in construction projects. The focal point of this research is to highlight their obstacles. A total of forty interviews were conducted and analyzed from four builders’ organizations and four suppliers’ organizations to ascertain their obstacles in coordinating the practice of off-site prefabrication. The results found the builder’s obstacles were sustainability, quality assurance (QA), mass production, CAD/BIM, technological support, commercial arrangements, system building, buffering in supply, schedule monitoring, productivity, flexibility, engagement, risks, and multiple supply arrangements. The supplier’s obstacles were design, financing and subcontracting, coordination, recognized practices, risks, multiple supply arrangements, and constraints. Moreover, the builders and suppliers had identified some ways to harmonize off-site prefabrication of timber. Some examples of timber prefabrication technology include joinery, doors and/or windows, structural floor/wall/roof frames, partitions, trusses, stairs, balustrades, and others. MEP services with in situ construction comprise the use of power sources and working coordination. The most important outcome of this investigation is that these obstacles can be addressed through collaboration and coordination. This is because there is a traditionally a lack of collaboration amongst builders and their suppliers. Furthermore, there is a lack of coordination between them in general. The research contributes to the improved timber and MEP services collaboration and coordination in off-site prefabrication, which can be referred to by other approaches of modular construction.
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Prediction of the mechanical properties of timber members in existing structures using the dynamic modulus of elasticity and visual grading parameters

https://research.thinkwood.com/en/permalink/catalogue3059
Year of Publication
2022
Topic
Mechanical Properties
Author
Arriaga, Francisco
Osuna-Sequera, Carlos
Bobadilla, Ignacio
Esteban, Miguel
Organization
Universidad Politécnica de Madrid
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Topic
Mechanical Properties
Keywords
Bending Strength
Existing Structures
In-situ Assessment
MOE
MOR
Research Status
Complete
Series
Construction and Building Materials
Summary
The modulus of elasticity and bending strength of 45 structural Salzmann pine timber pieces with nominal dimensions of 150x200x5400 mm3 from an existing 18th century structure were estimated by semi-destructive density estimation probing method (drilling chips extraction) and acoustic wave velocity (stress and ultrasound wave). Bending strength, modulus of elasticity and density were obtained according to the EN 408 European standard, and visual grading singularities were recorded. Visual grading methods are highly ineffective for existing timber structures. Sample mechanical properties show a typical profile of material from existing structures, and this was compared with the results of similar works. MOE and MOR predictive models were proposed with determination coefficients r2 of 66–68% and 51–52%, respectively, using dynamic MOE, relative edge knot diameter and slope of grain as independent variables. MOR prediction improved when these grading parameters were included.
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Study of Moisture Conditions in a Multi-Story Mass Timber Building through the Use of Sensors and WUFI Hygrothermal Modeling

https://research.thinkwood.com/en/permalink/catalogue1429
Year of Publication
2018
Topic
Moisture
Site Construction Management
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Kordziel, Steven
Organization
Colorado School of Mines
Year of Publication
2018
Format
Thesis
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Moisture
Site Construction Management
Keywords
Production
Construction
Moisture Content
Drying Rate
Hygrothermal
In Situ
Research Status
Complete
Summary
Mass timber products have shown promise as an innovative alternative to conventional framing systems for use in tall wood buildings, but this new trend in design and construction poses concerns for the long-term durability of the products. A major challenge that classically faces timber products is the threat of moisture-induced mold and decay fungi, which are a heightened concern in mass timber buildings exposed to the environment for extended duration during construction. Consequently, it is important to understand the hygric and thermal (hygrothermal) conditions that mass timber products can experience in multi-story constructions and to be able to quantify the behavior of the products for their suitable design and implementation. An eight-story mass timber building located in Portland, Oregon was chosen for this study and was instrumented for moisture content monitoring through its production, construction, and in-situ use. Record breaking precipitation levels occurred during the building’s construction and while dimension lumber and glulam products subsequently dried to acceptable levels, cross laminated timber products (CLT) dried more slowly. These measurements have an observed bias and the decay risk for the products is inconclusive. Samples of CLT used in the building were characterized for hygrothermal properties and integrated into WUFI, a simulation software, for analysis of the building. The software showed limitations for correctly simulating the behavior of CLT in isolated lab experiments and therefore a re-calibration was performed for accurate simulation. Preliminary on-site simulation results provide a decent approximation of observed data despite its high variance, but drying rate predicted by the program is lower than what was measured.
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Vibrational Behaviour of Cross Laminated Timber Floors in Residential Buildings

https://research.thinkwood.com/en/permalink/catalogue1738
Year of Publication
2016
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Zimmer, Severin
Augustin, Manfred
Year of Publication
2016
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Boundary Conditions
Serviceability Limit State
Elastomers
Frequency
In Situ
Laboratory Tests
Residential
Conference
World Conference on Timber Engineering
Research Status
Complete
Notes
August 22-25, 2016, Vienna, Austria p. 4835-4844
Summary
This paper will discuss the relevancy of different boundary conditions that relates to the dynamic behaviour of CLT floors to show the opportunities of adopting the findings for the verification of the serviceability limit state. Based on a literature research and measurements in the laboratory and in situ in different objects the evaluated boundary conditions are different static systems, supporting conditions, non-load bearing internal walls, flexible carriers, joints between CLT elements, elastomers and floor constructions. Furthermore a theoretical investigation on the low frequency behaviour of floating screeds was conducted. Abstracted from the results it can be stated that elastomers can generally be neglected in their influence on low frequency vibration modes except when the partial clamping due to the load of superimposed storeys at the supports should be taken into account. The effect of partial clamping on low frequency vibration can be calculated adequately but is lowered if elastomers are used to improve the building physics. A big influence was observed at non-load bearing internal walls as they are able to change the eigenmodes of a floor into ones with higher frequency. Overall the laboratory measurements agreed well with the analytic solutions while differences in comparison of calculations with in situ measurements rise with the complexity of the boundary conditions.
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Vibration Serviceability of Footbridges Made of the Sustainable and Eco Structural Material: Glued-Laminated Wood

https://research.thinkwood.com/en/permalink/catalogue2977
Year of Publication
2022
Topic
Acoustics and Vibration
Material
Glulam (Glue-Laminated Timber)
Author
Hawryszków, Pawel
Biliszczuk, Jan
Organization
Wroclaw University of Science and Technology
Editor
Li, Fengming
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
Glulam (Glue-Laminated Timber)
Topic
Acoustics and Vibration
Keywords
Footbridges
Dynamic Behaviour
In situ Measurement
Research Status
Complete
Series
Materials
Summary
In this paper, dynamic analyses of two untypical, modern footbridges made of glued-laminated timber are presented. One of them is among the longest cable-stayed bridges for pedestrians in the world, made of such a structural material. Both structures are qualified as having low sensitivity to vibrations. The results of numerical modal analysis using FEM and non-destructive experimental dynamic tests of investigated footbridges are compared. Important differences in obtained results are captured, which are identified as the positive effect in relation to design aspects. Moreover, the same in situ measurements confirm the high level of damping in footbridges made of glued-laminated wood, which is a very significant and distinguishing feature not commonly recognized. The study also calls attention to the choice of timber as an advisable material for footbridges. This is not only because of environmentally friendly and aesthetic reasons, but also due to providing highly satisfying vibration comfort for pedestrians.
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10 records – page 1 of 1.