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FE modeling of wooden building assemblies
Linnaeus University, Faculty of Science and Engineering, School of Engineering.
Linnaeus University, Faculty of Science and Engineering, School of Engineering.
2010 (English)In: InterNoise 2010-Lisbon Portugal 13-16 June, 2010, 1-10 p.Conference paper, Oral presentation only (Refereed)
Abstract [en]

Residential timber framed buildings have in some cases received complaints from inhabitants due to structure-borne sound at low frequencies, even if the building meets the regulations with respect to impact sound quality. This paper describes FE-analyses to evaluate the test setups of a building assembly and to prepare for the full-scale experimental modal analysis planned. By modal analysis, the dynamic properties of a structure, such as eigen modes and damping characteristics, can be extracted.

 

The test assembly consists of prefabricated wall and floor/roof timber elements. Different assembly and joining methods as well as building element are used. The eigen modes and damping differs between the assemblies investigated which influence the dynamic response in the lower frequencies. The results are carefully evaluated and planned measurements are discussed.

Place, publisher, year, edition, pages
2010. 1-10 p.
Keyword [en]
Structure-borne sound, modal analysis, dynamic response, FE analysis
National Category
Fluid Mechanics and Acoustics Building Technologies
Identifiers
URN: urn:nbn:se:lnu:diva-24561OAI: oai:DiVA.org:lnu-24561DiVA: diva2:607707
Conference
Inter.Noise 2010, 13-16 June, Lisbon
Available from: 2013-03-04 Created: 2013-02-25 Last updated: 2015-09-17Bibliographically approved
In thesis
1. Structural-acoustic vibrations in wooden assemblies:: Experimental modal analysis and finite element modelling
Open this publication in new window or tab >>Structural-acoustic vibrations in wooden assemblies:: Experimental modal analysis and finite element modelling
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
VIBRATIONER OCH STOMBURET LJUD I TRÄKONSTRUKTIONER : Experimentell modalanalys och finit elementmodellering
Abstract [en]

This doctoral thesis concerns flanking transmission in light weight, wooden multi-storey buildings within the low frequency, primarily 20-120 Hz. The overall aim is to investigate how the finite element method can contribute in the design phase to evaluate different junctions regarding flanking transmission.

Two field measurements of accelerations in light weight wooden buildings have been evaluated. In these, two sources; a stepping machine, and an electrodynamic shaker, were used. The shaker was shown to give more detailed information. However, since a light weight structure in field exhibit energy losses to surrounding building parts, reliable damping estimates were difficult to obtain.

In addition, two laboratory measurements were made. These were evaluated using experimental modal analysis, giving the eigenmodes and the damping of the structures. The damping for these particular structures varies significantly with frequency, especially when an elastomer is used in the floor-wall junction. The overall damping is also higher when elastomers are used in the floor-wall junction in comparison to a screwed junction. By analysing the eigenmodes, using the modal assurance criterion, of the same structure with two types of junctions it was concluded that the modes become significantly different. Thereby the overall behavior differs.

Several finite element models representing both the field and laboratory test setups have been made. The junctions between the building blocks in the models have been modeled using tie or springs and dashpots. Visual observation and the modal assurance criterion show that there is more rotational stiffness in the test structures than in the models.

The findings in this doctoral thesis add understanding to how modern joints in wooden constructions can be represented by FE modelling. They will contribute in developing FE models that can be used to see the acoustic effects prior to building an entire house. However, further research is still needed.

Abstract [sv]

Denna doktorsavhandling behandlar flanktransmission i flervåningshus med trästomme, inom det lågfrekventa området, främst 20-120 Hz. Det övergripande målet är att undersöka hur finita elementmetoden kan bidra i konstruktionsfasen för att utvärdera olika knutpunkters inverkan på flanktransmissionen.

Två fältmätningar av accelerationer i trähus har utvärderats. I dessa har två olika lastkällor använts, i den första en stegljudsapparat och i den andra en elektrodynamisk vibrator (shaker). Det visades att shakern kan ge mer detaljerad information, men eftersom vibrationerna även sprider sig till omgivande byggnadsdelar vid fältmätningarna var det svårt att estimera tillförlitliga dämpningsdata även då shaker användes.

Fältmätningarna följdes av två mätningar i laborationsmiljö. Dessa två experiment utvärderades med experimentell modalanalys, vilket ger egenmoder och dämpning hos strukturerna. Dämpningen för dessa trähuskonstruktioner varierar kraftigt med frekvens. Extra stora variationer registreras då en elastomer användes i knutpunkten mellan golv och vägg. Den totala dämpningen är generellt högre när elastomerer används i knutpunkten mellan golv och vägg i jämförelse med då knutpunkten är skruvad. Genom att analysera egenmoder och deras korrelationer (MAC), för samma trästruktur men med olika typer av knutpunkter, drogs slutsatsen att knutpunkten drastiskt förändrar strukturens dynamiska beteende.

Flera finita elementmodeller av både fält- och laboratorieuppställningar har gjorts. I dessa har knutpunkterna mellan byggnadsdelar modellerats helt styvt eller med hjälp av fjädrar och dämpare. Visuella observationer av egenmoder och korrelationen dem emellan visar att det finns mer rotationsstyvhet i försöken än i finita elementmodellerna.

Resultaten i denna doktorsavhandling har gett förståelse för hur knutpunkter i träkonstruktioner beter sig och kan simuleras med finit elementmodellering. Vidare kan resultaten bidra till utvecklingen av FE-modeller som kan användas för att kunna se de akustiska effekterna redan under konstruktionsstadiet. Dock behövs ytterligare forskning inom området.

Place, publisher, year, edition, pages
Växjö, Sweden: Linnaeus University Press, 2013. 100 p.
Series
Linnaeus University Dissertations, 115/2013
Keyword
wooden framed structure, light weight buildings, multi-storey, flanking transmission, junction, vibration distribution, impact noise, damping, elastomers, finite element analysis, experimental modal analysis, FRF, trästomme, träkonstruktion, träbyggnad, flervåningshus, EMA, FEM, flanktransmission, koppling, knutpunkt, vibrationsspridning, stomljud, stegljud, dämpning, elastomerer, finit elementmetod, experimentell modalanalys, accelerationsmätning, frekvensresponsfunktion, modalanalys
National Category
Building Technologies Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:lnu:diva-24562 (URN)978-91-87427-04-6 (ISBN)
Public defence
2013-03-15, Södrasalen, Hus M, Lückligs Plats 1, VÄXJÖ, Sweden, 14:24 (Swedish)
Opponent
Supervisors
Available from: 2013-02-28 Created: 2013-02-25 Last updated: 2013-02-28Bibliographically approved

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