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Olsson, J. & Linderholt, A. (2019). Force to sound pressure frequency response measurements using a modified tapping machine on timber floor structures. Engineering structures, 196, Article ID 109343.
Open this publication in new window or tab >>Force to sound pressure frequency response measurements using a modified tapping machine on timber floor structures
2019 (English)In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 196, article id 109343Article in journal (Refereed) Published
Abstract [en]

In recent years, research has shown that the lower frequency portion of impact sound, down to 20 Hz, is of significant importance to residents’ perception in buildings that have lightweight timber floors. At low frequencies, the finite element method is a useful tool for predictive analysis. Impact sound frequency response functions, which are easily calculated using finite element software, are useful as they offer a common ground for studies of correlations between measurements and analyzes. On the measurement side, the tapping machine is well defined and has become the standard excitation device for building acoustics. When using a tapping machine, the excitation force spectrum generated – necessary to achieving experimental frequency force to sound response functions – is unknown. Different equipment may be used for excitation and force measurements and if a structure behaves linearly, the use of any excitation devices should result in the same frequency response functions. Here, an ISO tapping machine hammer is fitted with an accelerometer, enabling estimates of input force spectra. In combination with measurements of the sound in the receiver room, frequency response functions are then achieved using an ISO tapping machine. Various excitation devices have been used on a floor partition in a timber building and on a cross-laminated timber (CLT) lab. floor in order to compare the resulting frequency response functions. Structural nonlinearities are evident, implying that for accurate frequency response measurements in acoustically low frequencies, excitation magnitudes and characteristics that are similar to these which stem from human excitations, should preferably be used.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Frequency response functions, Impact sound, Low-frequency, Measurements, Timber buildings, vibrations, Acoustic waves, Architectural acoustics, Finite element method, Floors, Measurement, Timber, Wooden buildings, Wooden floors, Frequency response
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-39426 (URN)10.1016/j.engstruct.2019.109343 (DOI)2-s2.0-85068054473 (Scopus ID)
Note

Funding details: Energimyndigheten; Funding details: Svenska Forskningsrådet Formas; Funding details: VINNOVA; Funding text 1: We would like to express our gratitude to those that have supported the work. The CLT floors were borrowed from the JSP2 project funded by Akademiska Hus. The measurements of the CLT floors were made within the BioInnovationen project FBBB, financed by VINNOVA, the Swedish Energy Agency, the Swedish Research Council Formas and by the participating organizations. The analyzes here were made within the Intereg Öresund-Kattegat-Skagerak project, Urban Tranquility. The measurements of the M-building were conducted within the ProWOOD research education program, funded by the Swedish Knowledge Foundation, Linænus University and RISE Research Institutes of Sweden. Appendix A

Available from: 2019-07-08 Created: 2019-07-08 Last updated: 2020-01-22Bibliographically approved
Johansson, M., Gustafsson, A., Olsson, J., Ylmen, P., Nord, T., Dorn, M., . . . Brännström, M. (2019). Framtidens biobaserade byggande och boende: Slutrapport.
Open this publication in new window or tab >>Framtidens biobaserade byggande och boende: Slutrapport
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2019 (Swedish)Report (Other academic)
Abstract [en]

The aim

of the project "Biobased building and living for the future" was to create conditions for increased use of bio-based products and services in the construction sector in Sweden and Europe and to increase the competitiveness of the Swedish timber manufacturing industry. The project has shown ways to develop E-commerce, parts of the production where increased digitalization leads to increased capacity and quality, as well as solutions for development of floor systems, external walls and tall timber buildings. The project has shown development opportunities to increase the use of bio-based products that implemented will increase competitiveness.

The project has been divided into eleven sub-projects to study the various aspects of external factors, market conditions and business models, process development and product development. Within each sub-project, several workshops have been carried out to jointly evaluate results and decide the next step in the sub-project. Through joint workshops, the partners have also been able to meet and share results across the sub-projects and spread knowledge and create networks within the industry. The last part is perceived as very valuable by both the companies and the academy / institute.

For the joinery value chain, a current situation analysis has been carried out and shown how the development of E-commerce platforms must be combined with process development in order to have a large effect. The results will be utilized in the companies' strategy work ahead. For the timber building value chain, demonstrators have shown development opportunities for both process and product development. The next step for the companies is to evaluate the various solutions linked to their own production conditions.

Publisher
p. 100
Series
RISE Rapport ; 2019:18
Keywords
Joinery industry, Wood manufacturing, Timber Building, Product development, Process development
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-38177 (URN)978-91-88907-44-8 (ISBN)
Available from: 2019-03-13 Created: 2019-03-13 Last updated: 2020-01-22Bibliographically approved
Olsson, J. (2019). Low Frequency Impact Sound in Timber Buildings: Transmission Measurements and Simulations. (Doctoral dissertation).
Open this publication in new window or tab >>Low Frequency Impact Sound in Timber Buildings: Transmission Measurements and Simulations
2019 (English)Doctoral thesis, monograph (Other academic)
Abstract [en]

An increased share of multi-story buildings that have timber structures entails potential in terms of increased sustainability as well as human-friendly manufacturing and habitation. Timber buildings taller than two stories were prohibited in Europe until the 1990s due to fire regulations. In 1994, this prohibition was removed in Sweden. Thus, being a rather new sector, the multi-story timber building sector lags behind in maturity compared to the multi-story concrete sector. The low-frequency range down to 20 Hz has been shown to be important for the perception of the impact of sound in multi-story apartments with lightweight floors. This frequency range is lower than the one that has traditionally been measured according to standards and regulations. In small rooms, the measurement conditions tend to go from diffuse fields above 100 Hz to modal sound fields dominated by few resonances, below 100 Hz. These conditions lead to new challenges and to new possibilities for measurements and modelling. In the present research, a frequency response functions (FRFs) strategy aimed to simplify simulations and correlations between the simulations and test results was used. Measurements made indicate that, in the low frequencies, the highest sound pressures occur at the floor level opposite the ceiling / floor that is excited. By having an iterative measurement strategy with several microphones and making measurements until a required standard error is obtained, it is possible to gain a desired precision and information about the statistical distribution of both the sound fields and floor insulation performance. It was also found that, depending on the excitation source, the FRF from an excitation point on the floor above to the sound pressure at a microphone position in the room below may differ. This indicates that non-linearities in sound transmissions are present. Thus, the excitation source used in a test should be similar in force levels and characteristics to the real excitation stemming, for instance, from a human footfall, to achieve reliable measurement results. The ISO rubber ball is an excitation source that is close to fulfilling this need. In order to obtain an FRF, the impact force must be known. A rig that enables the impact force from a rubber ball to be measured was developed and manufactured. The results show that the force spectra are the same up to about 55 Hz, regardless of the point impedances of the floors excited in the tests. Similar results have been found by others in tests with human excitations. This means that FRFs up to about 55Hz can be achieved without actually measuring the excitation force. On the calculation side, finite element simulations based on FRFs may offer advantages. FRFs combined with the actual excitation force spectra of interest give the sound transmission. At higher frequencies, it is more important to extract the point mobilities of the floors and relate them to the excitation forces. By using an infinite shaft, sound transmission can be studied without involving reverberation time. The calculation methodology is used in the present research to evaluate different floor designs using FE models.

Keywords
Timber floors, FE-simulations, Light weight floors, Frequency response functions, Building acoustics
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-42366 (URN)
Note

Linnaeus University Press, 2019. s. 162SerieLinnaeus University Dissertations ; 364

Disputation 2019-11-19, Södrasalen, Hus M, Växjö, 09:30 (Svenska)

Opponent: Hopkins, Carl, Professor

Handledare: Linderholt, Andreas, Dr. Nilsson, Börje, Professor

Forskningsfinansiär: KK-stiftelsen

Available from: 2019-12-19 Created: 2019-12-19 Last updated: 2020-01-22Bibliographically approved
Olsson, J. & Linderholt, A. (2018). Low-frequency impact sound pressure fields in small rooms within lightweight timber buildings — Suggestions for simplified measurement procedures. Noise Control Engineering Journal, 66(4), 324-339
Open this publication in new window or tab >>Low-frequency impact sound pressure fields in small rooms within lightweight timber buildings — Suggestions for simplified measurement procedures
2018 (English)In: Noise Control Engineering Journal, ISSN 0736-2501, E-ISSN 2168-8710, Vol. 66, no 4, p. 324-339Article in journal (Refereed) Published
Abstract [en]

Low-frequency impact sound insulation, down to 20 Hz, has a significant effect on humans' dissatisfaction due to noise in timber buildings. Today, the low-frequency procedure of the ISO 16283-2:2015 impact sound measurement standard covers the frequency range down to 50 Hz for the use of an ISO tapping machine, but does not yet cover the use of an ISO rubber ball. Here, microphone grid measurements were made in two small rooms that were excited by an ISO rubber ball from the rooms above. In each grid, 936 microphone positions were used to capture data representing the full spatial fields of impact sound pressures from 10 to 500 Hz for one excitation location for each room. The data show that the positions at the radiating ceiling surfaces have low maximum sound pressure levels compared to the pressure levels at the floors, especially in the floor corners. First, a measurement procedure to predict the maximum exposure of low-frequency sound in a room is proposed It is suggested that the maximum values for each frequency band in the corners opposite to the partition being excited (i.e., the floor corners) be used. Second, a procedure to predict the room average sound pressure level and the prediction's normal distribution is suggested. Iterative measurements with random microphone locations and random excitation locations are used. The advantage of this method is that the required precision and information about the sensitivity due to different excitation points are obtained.

Keywords
Acoustic variables measurement, Acoustic wave transmission, Acoustic waves, Architectural acoustics, Fire alarm systems, Floors, Forecasting, Iterative methods, Location, Microphones, Normal distribution, Rubber, Timber, Wooden buildings, Impact sound insulation, Impact sound measurements, Low-frequency sounds, Measurement procedures, Microphone positions, Random excitations, Required precision, Sound pressure level, Sound insulation
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-35707 (URN)10.3397/1/376628 (DOI)2-s2.0-85052959047 (Scopus ID)
Note

 Funding details: FEDER, European Regional Development Fund;

Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2020-01-22Bibliographically approved
Olsson, J. & Linderholt, A. (2018). Measurements of low frequency impact sound transfer functions of light weight timber floors, utilizing the IsO rubber ball. In: 25th International Congress on Sound and Vibration 2018, ICSV 2018: Hiroshima Calling. Paper presented at 25th International Congress on Sound and Vibration 2018: Hiroshima Calling, ICSV 2018, 8 July 2018 through 12 July 2018 (pp. 476-483). International Institute of Acoustics and Vibration, IIAV
Open this publication in new window or tab >>Measurements of low frequency impact sound transfer functions of light weight timber floors, utilizing the IsO rubber ball
2018 (English)In: 25th International Congress on Sound and Vibration 2018, ICSV 2018: Hiroshima Calling, International Institute of Acoustics and Vibration, IIAV , 2018, p. 476-483Conference paper, Published paper (Refereed)
Abstract [en]

Impact sound below 100 Hz is an important issue for light weight timber buildings. It is also well known that finite element model simulations are more beneficial in the low frequency range than in higher frequencies due to the longer wavelengths allowing the element meshes to be coarser. Utilizing transfer functions to describe impact sound would imply simplifications to correlate data stemming from measurements and low frequency finite element models. If the impact force is known, the simulations become easier since there would not be any need for the modelling of the impact mechanisms, just calculations of the transfer functions which are then combined with the force spectrum to give the resulting sound pressure. The impact ball has shown to be in close resemblance with a human's excitation in the low frequency range which makes it a suitable excitation device. However, when its force spectrum is needed, it may be hard in practice to achieve that during a regular measurement since the ball is not easily equipped with a force gauge. Here, two different methods are investigated. An investigation of the repeatability of the force spectrum of the rubber ball in the low frequency range for floors having different mobilities is made. To enable this, an equipment for field measurements of impact force spectrum and potentially point mobilities using an ISO ball, is designed, manufactured and evaluated. Impact force measurements are made on lightweight timber as well as concrete floors, with different properties for comparisons. Within the lowest frequencies it is potentially possible to use one given force spectrum from the ISO ball together with impact sound measurements for the creation of impact force to sound transfer functions on different floors.

Place, publisher, year, edition, pages
International Institute of Acoustics and Vibration, IIAV, 2018
Keywords
Ball, Impact sound, Low frequency, Acoustic waves, Architectural acoustics, Finite element method, Floors, Force measurement, Rubber, Timber, Wooden buildings, Excitation devices, Field measurement, Higher frequencies, Impact sound measurements, Low frequency range, Low-frequency, Transfer functions
National Category
Civil Engineering
Identifiers
urn:nbn:se:ri:diva-37272 (URN)2-s2.0-85058680787 (Scopus ID)9781510868458 (ISBN)
Conference
25th International Congress on Sound and Vibration 2018: Hiroshima Calling, ICSV 2018, 8 July 2018 through 12 July 2018
Available from: 2019-01-18 Created: 2019-01-18 Last updated: 2020-01-22Bibliographically approved
Linderholt, A. & Olsson, J. (2017). A simulation based study of low frequency transient sound radiation from floors - A concrete vs. a hybrid floor. In: 24th International Congress on Sound and Vibration, ICSV 2017: . Paper presented at 24th International Congress on Sound and Vibration, ICSV 2017, 23 July 2017 through 27 July 2017.
Open this publication in new window or tab >>A simulation based study of low frequency transient sound radiation from floors - A concrete vs. a hybrid floor
2017 (English)In: 24th International Congress on Sound and Vibration, ICSV 2017, 2017Conference paper, Published paper (Refereed)
Abstract [en]

Timber is a renewable and human friendly construction material and thereby a potential solution to achieve life cycle sustainable buildings. However, it is clear that impact sound and vibrations wit hin the low frequency range still are challenges for wooden joist floors. Another challenge is the, mostly, larger building heights of wooden or hybrid floors compared to the heights of concrete floors. Using timber as the structural joist floor material could imply fewer stories due to maximum allowed building heights, which renders in less income in a building project. Accurate simulations of impact sound may decrease the need for prototypes; thus saving money and time in the timber building industry. Here, a hybrid joist floor consisting of wood, sand and steel is compared to a concrete floor in terms of radiated impact sound into a rectangular cavity. The hybrid floor is designed such that its mass distribution and globa l stiffness are close to the same properties of the concrete floor. Finite element models are used for simulations of the radiated transient sound induced by impact forces having the characteristics of human walking. The simulations indicate that similar surface mass and bending stiffness of a floor intersection give similar impact sound transmission properties around the first bending mode, while it is not necessary so at higher frequencies.

Keywords
Impact sound, Simulation, Timber buildings, Acoustic waves, Architectural acoustics, Building materials, Buildings, Concrete construction, Concretes, Construction industry, Finite element method, Intelligent buildings, Life cycle, Stiffness, Timber, Wooden buildings, Wooden floors, Higher frequencies, Impact sound transmissions, Low frequency range, Rectangular cavity, Sustainable building, Floors
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-33134 (URN)2-s2.0-85029438254 (Scopus ID)
Conference
24th International Congress on Sound and Vibration, ICSV 2017, 23 July 2017 through 27 July 2017
Note

 Funding details: National Space Biomedical Research Institute; Funding details: Knowledge Foundation; Funding details: University of Miami

Available from: 2018-01-31 Created: 2018-01-31 Last updated: 2020-01-22Bibliographically approved
Scheepers, G., Olsson, J., Lycken, A., Grahn, T., Lundqvist, S.-O. & Hagman, O. (2017). Hållfasthetsbestämning av virke med en NIR-kamera.
Open this publication in new window or tab >>Hållfasthetsbestämning av virke med en NIR-kamera
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2017 (Swedish)Report (Other academic)
Abstract [sv]

SP, Innventia och Luleås Tekniska Universitet har genomfört en förstudie där man undersökte om nära-infrarött (NIR) data kan bidra till säkrare hållfasthetsbestämning av virke. För att göra det behövdes förutom NIR-data, dels data som konventionellt används i sågverk för att göra hållfasthets-uppskattningar, dels referensdata från mekanisk provning.

Följande data samlades in från 100 granplankor med dimensionen 3600*150*45 mm3:

1. mått, vikt, och därmed densitet,

2. egenfrekvenser via dynamisk excitering,

3. högupplösta NIR-bilder på 2 flatsidor av varje planka,

4. RGB och fibervinkeldata från flat- och kantsidorna,

5. röntgentomografibilder,

6. förstörande böjtestdata, med bestämning av lokal och global E-modul, och

7. kvalitativ inventering av brottyp och kvistposition.

 

Databasen är i sig en värdefull resurs och en god grund för fortsatt forskning och utveckling mot kun-skap och tillämpningar baserat på information som hittills inte utvärderats och nyttjats.

Virkesegenskaper som påverkar hållfasthet, såsom tjurved, kunde identifieras och visualiseras. Andra egenskaper som är viktiga hållfasthetsindikatorer, såsom egenfrekvens och densitet, kunde predikteras med multivariata modeller baserade på NIR-spektraldata. Inledande modellförsök visar att det går att prediktera global E-modul med multivariata modeller baserade på NIR-spektraldata med ungefärlig samma precision som industriell hållfasthetsbedömning med dynamisk excitering. De NIR-data som användes i modelleringen var dock bara medelvärden över hela plankan. Därför finns det god potential för bättre prediktion med mer riktade variabler, som speglar de spatiala variationerna i varje planka, t.ex. runt kvistar, vilket blir ämnet för ett eventuellt fortsättningsprojekt.

Projektet finansierades av Norrskogs Forskningsstiftelse, Stiftelsen Åforsk, Träcentrum Norr, och Södra Skogsägarnas Stiftelse för Forskning, Utveckling och Utbildning. Individer som medverkade i projektet inkluderar Gerhard Scheepers, Jörgen Olsson, Anders Lycken, Sven-Olof Lundqvist och Thomas Grahn (RISE Bioekonomi); och Olle Hagman (LTU). RemaSawco och JGA i Linneryd hjälpte också med insamlingen av fibervinkeldata.

 

Publisher
p. 21
Series
SP Rapport, ISSN 0284-5172 ; 2017:08
Keywords
Near infrared, measurement technology, vision technology, wood, timber, lumber, Nära infrarött, mätteknik, visionteknik, trä, virke
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:ri:diva-28171 (URN)
Available from: 2017-02-13 Created: 2017-02-13 Last updated: 2020-01-22Bibliographically approved
Olsson, J. & Linderholt, A. (2016). Impact evaluation of a thin hybrid wood based joist floor. In: Proceedings of ISMA 2016: International Conference on Noise and Vibration Engineering. Paper presented at International Conference on Noise and Vibration Engineering 2016 (ISMA 2016), September 19-21, 2016, Leuven, Belgium (pp. 589-602).
Open this publication in new window or tab >>Impact evaluation of a thin hybrid wood based joist floor
2016 (English)In: Proceedings of ISMA 2016: International Conference on Noise and Vibration Engineering, 2016, p. 589-602Conference paper, Published paper (Refereed)
Abstract [en]

The purpose of this paper is twofold. The first aim is to develop a numericalanalysis procedure, by combining FRFs from FE-models with analyticalformulas for sound emission and transmission from the ceiling anddownwards within a room with four walls. The aim is to, by applying thisapproach; accomplish a tool which calculates the relative impact soundbetween different joist floors, in the low frequency range. The second aim is tobenchmark a thin hybrid wooden based joist floor with similar thickness,surface weight and global bending stiffness as a concrete hollow core floorstructure. What will be the difference in sound transmission? The question isrelevant since it may be necessary to make thinner wood based joist floors inhigh rise buildings, if wood should stay competitive against concrete. Theresults show that the direct transmissions of impact sound are very similararound the first bending mode. As the frequency increases, the modes in thestructures differ significantly. Below 100 Hz, the concrete floor has 4 modes,while the hybrid joist floor has 9 modes. As the frequency increases the soundradiation characteristics differs. The results show that it is possible to havesimilar sound transmission properties around the first bending modes for ahybrid based joist floor and a hollow core concrete floor structure with similar thicknesses. At the first modes of the structure, the information about thesurface weight and global bending stiffness are useful for prediction of soundtransmission properties but for higher modes, they are not sufficient.

National Category
Building Technologies
Identifiers
urn:nbn:se:ri:diva-36984 (URN)978-1-5108-3591-7 (ISBN)
Conference
International Conference on Noise and Vibration Engineering 2016 (ISMA 2016), September 19-21, 2016, Leuven, Belgium
Funder
Interreg Öresund-Kattegat-Skagerrak
Note

The FE-Model development of the joist floor made within the ProWOOD research education program,funded by the Swedish Knowledge foundation, Linnæus University and SP Technical Research Institute ofSweden. The further sound radiation analysis of the joist floors was made within the Intereg Öresund-Kattegat-Skagerak project Urban Tranquililty.

Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2020-01-22Bibliographically approved
Olsson, J. & Linderholt, A. (2016). Low Frequency Force to Sound Pressure Transfer Function Measurements Using a Modified Tapping Machine on a Light Weight Wooden Joist Floor. In: WCTE 2016: World Conference on Timber Engineering. Paper presented at World Conference on timber engineering (WCTE 2016), August 22-25, 2016, Vienna, Austria (pp. 2888-2895).
Open this publication in new window or tab >>Low Frequency Force to Sound Pressure Transfer Function Measurements Using a Modified Tapping Machine on a Light Weight Wooden Joist Floor
2016 (English)In: WCTE 2016: World Conference on Timber Engineering, 2016, p. 2888-2895Conference paper, Published paper (Refereed)
Abstract [en]

In recent years research has shown that low frequency impact sound is of significant importance for inhabitants´ perception of impact sound in buildings with light weight wooden joist floors. The tapping machine is well defined as an excitation device and is a standard tool for building acoustics. However, the excitation force spectrum generated for each individual floor is unknown when using a tapping machine. In order to increase the possibilities to compare simulations to impact sound measurements, there is a need for improvement of impact sound measurement methods. By measuring the input force spectrum by a modified tapping machine and the sound in the receiver room, transfer functions can be achieved.In the light weight wooden building used for the evaluation test of the proposed method, structural nonlinearities are evident in the frequency response functions stemming from different excitation levels. This implies that for accurate FRF-measurements in low frequencies, excitation magnitudes that are similar to these stemming from human excitations should preferably be used.

Keywords
Low-frequency impact sound, light weight wooden joist floor, tapping machine, frequency response functions
National Category
Building Technologies
Identifiers
urn:nbn:se:ri:diva-36983 (URN)978-3-903024-35-9 (ISBN)
Conference
World Conference on timber engineering (WCTE 2016), August 22-25, 2016, Vienna, Austria
Projects
ProWood
Note

The study was conducted within the ProWOOD researcheducation program, funded by the Swedish Knowledgefoundation, Linnæus University and SP TechnicalResearch Institute of Sweden.

Available from: 2019-01-07 Created: 2019-01-07 Last updated: 2020-01-22Bibliographically approved
Olsson, J. (2016). Low Frequency Impact Sound in Timber Buildings: Simulations and Measurements. (Licentiate dissertation). Linnaeus University
Open this publication in new window or tab >>Low Frequency Impact Sound in Timber Buildings: Simulations and Measurements
2016 (English)Licentiate thesis, monograph (Other academic)
Abstract [en]

An increased share of construction with timber is one possible way of achieving more sustainable and energy-efficient life cycles of buildings. The main reason is that wood is a renewable material and buildings require a large amount of resources. Timber buildings taller than two storeys were prohibited in Europe until the 1990s due to fire regulations. In 1994, this prohibition was removed in Sweden.     Some of the early multi-storey timber buildings were associated with more complaints due to impact sound than concrete buildings with the same measured impact sound class rating. Research in later years has shown that the frequency range used for rating has not been sufficiently low in order to include all the sound characteristics that are important for subjective perception of impact sound in light weight timber buildings. The AkuLite project showed that the frequency range has to be extended down to 20 Hz in order to give a good quality of the rating. This low frequency range of interest requires a need for knowledge of the sound field distribution, how to best measure the sound, how to predict the sound transmission levels and how to correlate numerical predictions with measurements.     Here, the goal is to improve the knowledge and methodology concerning measurements and predictions of low frequency impact sound in light weight timber buildings. Impact sound fields are determined by grid measurements in rooms within timber buildings with different designs of their joist floors. The measurements are used to increase the understanding of impact sound and to benchmark different field measurement methods. By estimating transfer functions, from impact forces to vibrations and then sound pressures in receiving rooms, from vibrational test data, improved possibilities to correlate the experimental results to numerical simulations are achieved. A number of excitation devices are compared experimentally to evaluate different characteristics of the test data achieved. Further, comparisons between a timber based hybrid joist floor and a modern concrete floor are made using FE-models to evaluate how stiffness and surface mass parameters affect the impact sound transfer and the radiation.     The measurements of sound fields show that light weight timber floors in small rooms tend to have their highest sound levels in the low frequency region, where the modes are well separated, and that the highest levels even can occur below the frequency of the first room mode of the air. In rooms with excitation from the floor above, the highest levels tend to occur at the floor levels and in the floor corners, if the excitation is made in the middle of the room above. Due to nonlinearities, the excitation levels may affect the transfer function in low frequencies which was shown in an experimental study. Surface mass and bending stiffness of floor systems are shown, by simulations, to be important for the amount of sound radiated.     By applying a transfer function methodology, measuring the excitation forces as well as the responses, improvements of correlation analyses between measurements and simulations can be achieved

Place, publisher, year, edition, pages
Linnaeus University, 2016
Keywords
Low-frequency, impact sound, light weight floor, timber joist floor, tapping machine, multi-storey timber building, frequency response functions., Stegljud
National Category
Natural Sciences
Identifiers
urn:nbn:se:ri:diva-42365 (URN)
Note

Opponent:Kari, Leif, Professor

Handledare: Linderholt, Andreas, Lektor

ProjektProWoodSilent Timber BuildUrban TranquilityBioInnovation FBBB

Forskningsfinansiär: KK-stiftelsen

Delarbeten:

1. Low frequency measurements of impact sound performance in light weight timber frame office buildings

2. Low frequency sound pressure fields in small rooms in wooden buildings with dense and sparse joist floor spacings

3. Low Frequency Force to Sound Pressure Transfer Function Measurements Using a Modified Tapping Machine on a Light Weight Wooden Joinst Floor4. Impact evaluation of a thin hybrid wood based joist floor

Available from: 2019-12-19 Created: 2019-12-19 Last updated: 2020-01-22Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-0019-4568

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