| 1. |
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| 2. |
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| 3. |
- Blomqvist, Lars, 1962-, et al.
(författare)
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Framtidens resurseffektiva KL-trä – en spaning
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Korslimmat trä (KL-trä) för byggnadsändamål är en produkt som togs fram i Centraleuropa i mitten av 1990-talet. Syftet med förstudien är att i samverkan utforska förslag för hur en framtida resurseffektivare KL-träprodukt kan utformas. Målet är att ta fram underlag för utveckling och genera en samling kring frågan. Det finns en medvetenhet för de omvärldsfaktorer som påverkar byggandet med KL-trä. Det finns en ökad efterfrågan på trä i byggsektorn och det finns ett dynamiskt tänkesätt för att ersätta betong med KL-trä. Ökad användning av skogsråvara, global uppvärmning och minskad tillgång via begränsningar i skogsbruk väcker frågor. Vilken råvara har vi i framtiden, vilka trädslag och hur ser tillgången ut? Det resulterande materialet har analyserats utifrån de olika perspektiven som representeras av intressentgrupperna i värdekedjan för byggande med KL-trä. Rapporten avslutas med projektidéer som framkom under arbetet med förstudien.
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| 4. |
- Bolmsvik, Åsa, 1975-, et al.
(författare)
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FE modeling of a lightweight structure with different junctions
- 2012
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Ingår i: Proceedings of EURONOISE 2012. - : European Acoustics Association. - 9788001050132 ; , s. 162-167
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Konferensbidrag (refereegranskat)abstract
- In lightweight structures it is common to use damping material in junctions to decrease sound transmission. In field measurements, the damping properties of the structure are easily overestimated due to the omnipresent energy losses to the surroundings. Thus, reliable estimates of structural properties cannot be guaranteed. Vibrational tests were done on a full scale wooden construction, consisting of a floor and supporting beams, representing walls, to investigate the effect of different junctions. Totally seven different setups were made using the same building components. In one setup the floor and the walls were screwed together, in five setups different elastomers was positioned between the floor and the walls and in the last setup the floor was resting free on top of the walls. A shaker, with pseudorandom excitation, was used for the excitation of the structure and accelerometers were used for response measurements. The effect of the junction was investigated by studying the acceleration levels in the edge part of the floor-wall junction in different directions. Modal data, extracted from test data using experimental modal analysis, form input and validation data for the following finite element (FE) analysis. Two FE models; modeling one elastomer and the screwed setup, are used for the studies. The aim was to study if the eigenmodes rendering the acceleration levels are similar in test and in analysis, using common material properties. The results from correlation between test and analytical results show that the material properties of the wood need to be known better; more sophisticated models are needed to fully simulate the dynamic behavior of the structure. Anyhow, with the used properties the mode shapes are captured fairly well in the lower frequencies. Furthermore, the experiment shows that the damping properties of the junction material have a major influence on the behavior of the structure.
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| 5. |
- Ditlevsen, Ove, et al.
(författare)
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Variation of bending strength along structural timber members
- 1997
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I denna rapport presenteras tre konferensbidrag om variationen i böjhållfasthet längs konstruktionsvirke. Samtliga bidrag behandlar ett pågående forskningsprojekt där den andra fasen nyligen avslutats.
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| 6. |
- Hongisto, Valtteri, et al.
(författare)
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PERCEPTION OF IMPACT SOUNDS THROUGH WOODEN FLOORS WAS EXPLAINED BY FREQUENCIES 100-3150 Hz - PSYCHOACOUSTIC EXPERIMENT ON ANNOYANCE
- 2023
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Ingår i: <em>Proceedings of Forum Acusticum </em>2023. - : European Acoustics Association, EAA.
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Konferensbidrag (refereegranskat)abstract
- The most popular single-number quantities (SNQs) of impact sound insulation in Europe are L’n, w and L’nT, w. They are based on measurements within 100-3150 Hz. Recently, it was proposed that the measurements should be extended down to 25 Hz for wooden floors, and L’nT, w+CI, 25 should replace L’nT, w. The purpose of this study is to analyze which of the two SNQs, Ln, w or LnT, w+CI, 25, predicts the annoyance of natural impact sounds better for wooden floors. We conducted a psychoacoustic experiment, where 52 participants rated the annoyance of 75 impact sounds. As stimuli, five types of natural impact sounds were used. They were recorded for 15 different wooden floors built in an impact sound insulation laboratory, where also their SNQs were measured. Based on correlation analysis, Ln, w explained annoyance of natural impact sounds equally well or better than Ln, w+CI, 25, depending on impact sound type Therefore, based on perception, it seems to be sufficient to conduct measurements within 100-3150 Hz for wooden floors and assess their sound insulation using L’nT, w or L’n, w © 2023 First author et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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| 7. |
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| 8. |
- Hongisto, Valtteri, et al.
(författare)
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Sound insulation dataset of 30 wooden and 8 concrete floors tested in laboratory conditions
- 2023
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Ingår i: Data in Brief. - : Elsevier Inc.. - 2352-3409. ; 49
-
Tidskriftsartikel (refereegranskat)abstract
- In a Finnish-Swedish consortium project, a large amount of sound insulation tests was conducted for several intermediate floors in laboratory conditions to serve various scientific research questions. The dataset contains 30 wooden and 8 concrete constructions which are commonly used between apartments in multistorey buildings. Impact sound insulation was determined according to ISO 10140-3 standard using both tapping machine and rubber ball as standard sound sources. Airborne sound insulation was determined according to the ISO 10140-2 standard. The data are special since they have a broad frequency range: 20−5000 Hz. Data are reported in 1/3-octave frequency bands and the single-number values of ISO 717-1 and ISO 717-2 are also reported. Detailed construction drawings are available for all reported constructions. The data are highly valuable for research, education, and development purposes since all data were obtained in the same laboratory (Turku University of Applied Sciences, Turku, Finland), and all the constructions were built by the same installation team. © 2023 The Authors
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| 9. |
- Hongisto, Valtteri, et al.
(författare)
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Suitability of standardized single-number ratings a of impact sound insulation for wooden floors : Psychoacoustic experiment
- 2023
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Ingår i: Building and Environment. - : Elsevier. - 0360-1323 .- 1873-684X. ; 244
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Tidskriftsartikel (refereegranskat)abstract
- Wooden floors usually have worse impact sound insulation (ISI) at low frequencies than concrete floors having the same rating level. Rating level is usually expressed by single-number quantities (SNQs), such as weighted impact sound pressure level Ln,w. Psychoacoustic research among wooden floors is very limited although a controlled laboratory experiment is the strongest method to point out the most adequate SNQs to be declared for the floors. The purpose of our study was to determine how four standardized SNQs of ISO 717-2, Ln,w, Ln,w +CI, Ln,w +CI,50, and LiA,Fmax,V,T, and a recently proposed SNQ, Ln,w +CI,25, are associated with the annoyance of natural impact sounds transmitted through wooden floors. Fifteen floors were built in the laboratory based either on cross laminated timber (heavy) or open box wood (light) slabs. Different coverings and suspended ceilings were applied on these slabs. The ISI was tested within 25-3150 Hz using both tapping machine and rubber ball. Thereafter, five natural impact sounds were recorded for each floor: rubber ball drops, steel ball drops, walking, jumping, and chair pushing. Fifty-two people rated the annoyance of these 75 recorded natural impact sounds in psychophysics laboratory. Annoyance was best associated with Ln,w for all the five impact sound types. That is, measurement of ISI within 100-3150 Hz is sufficient from subjective point of view. All four SNQs based on tapping machine explained annoyance better than the SNQ based on rubber ball. Our results can significantly guide the future research, development, and regulations of wooden floors.
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| 10. |
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| 11. |
- Jarnerö, Kirsi, et al.
(författare)
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Bjälklagsvibrationer – Vad innebär den nya EK5?
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Floor vibrations – Implications of the new EC5? This report presents the design methodology principles for the revised section for the control of vibrations in wooden floors, as well as the proposal for dividing timber floors into performance levels and quality selection, as found in Eurocode 5 With the aim of presenting how different floors commonly used in Sweden performs with respect to the new methodology, the results from a limited parameter study are presented. A total of eight different floor types were examined, including floor structures with load-bearing beams made of structural timber, glulam, LVL, and I-joists. The study also looked at rib joists with T-beams made of glulam combined with an LVL board, as well as floor structures with a load bearing CLT board. The following parameters were varied to study effect on the stiffness of the structures: • the centre distance between beams • the web height of the beam cross-section for rib-floor slabs, • thickness of load bearing CLT board. The maximum span for each floor structure was decided by finding the maximum span for each floor structure which meets the ultimate limit state and the serviceability limit state conditions, both with respect to deformations and vibrations for residential and office buildings set by the new EC5. The stiffness of each floor was then increased to study the effect of stiffness on the performance levels. Response factors were calculated for each case. Note! Direct comparison of the floor structures is not possible since the calculations are based on different span widths for each floor type. Since the calculations are based on each floor type’s unique conditions, it is not possible to compare the floor structures directly. Instead, comparisons must be made based on how a variation in stiffness affects the performance level of each individual floor type. The parameter study shows that for the light floor structures with discrete beams, spacing the beams closer changes the response factor slightly but it typically stays within the values for performance level V, i.e. between 24 and 36. For the other floor structures, rib floor and CLT, increasing the stiffness resulted in a larger change in performance and some floors changed floor performance level. The performance levels and quality choices introduced in the new methodology for checking vibrations in timber floors, makes it easier and clearer for clients and builders to achieve a consensus on what vibration comfort to expect in the finished building. This is an opportunity to reduce the risk of complaints and avoid having to take action to correct a perceived lack of quality. The current advice in the national annex for the Eurocode EKS12 specifies that the deflection for a 1 kN point load is limited to 1.5 mm, which corresponds to the upper deflection limit for performance level V. Performance level V is the worst performance level allowed for the quality choice ‘Economy’ for offices and homes in multi-family buildings. This means that the proposal on quality choice does not provide any tightening compared to the Swedish requirement in EKS12. However, the fact that performance level VI is allowed for dwellings in single-family houses with an upper limit value for deflection of 2.0 mm suggests that the proposal mitigates the requirement contained in EKS12.
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| 12. |
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| 13. |
- Jarnerö, Kirsi, et al.
(författare)
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Effect of flexible supports on vibration performance of timber floors
- 2012
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Ingår i: Euronoise, Prague 2012, 10-13 June, 2012. - : European Acoustics Association (EAA). - 9788001050132 ; , s. 214-219
-
Konferensbidrag (refereegranskat)abstract
- In residential multi-storey buildings of timber it is of great impor-tance to reduce the flanking transmission of noise. Some buildingsystemsdothisbyinstallingavibration-dampingelasticinterlayer,Sylomerror Sylodynr, in the junction between the support andthefloorstructure.Thisinterlayeralsoimprovesthefloorvibrationperformance by adding damping to the structure. In the presentwork the vibration performance of a floor with such interlayershas been investigated both in laboratory and field tests. A pre-fabricated timber floor element was tested in laboratory on rigidsupports and on supports with four different types of interlayers.Theresultsarecomparedwithin situtests on a copy of the samefloorelement.Theeffectonvibrationperformancei.e.frequencies,damping ratio and mode shapes is studied. A comparison of theinsitutestandthetestwithelasticinterlayerinlaboratoryshowsthatthe dampingin situis approximately three times higher than on asingle floor element in the lab. This indicates that the dampinginsituisaffectedbethesurroundingbuildingstructure.Theachieveddamping ratio ishighly dependent onthe mode shapes. Mode sha-pes that have high mode shape coefficients along the edges wherethe interlayer material is located, result in higher modal dampingratios. The impulse velocity response, that is used to evaluatethe vibration performance and rate experienced annoyance in thedesign of wooden joist floors, seems to be reduced when adding elastic layers at the supports.
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| 14. |
- Jarnerö, Kirsi, et al.
(författare)
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Effect of flexible supports on vibration performance of timber floors
- 2012
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Ingår i: Proceedings of EURONOISE 2012. - : European Acoustics Association. ; , s. 214-219
-
Konferensbidrag (refereegranskat)abstract
- 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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| 15. |
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| 16. |
- Jarnerö, Kirsi, et al.
(författare)
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In situ testing of timber floor vibration properties
- 2010
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Ingår i: <em>Proceedings of the 11th World Conference on Timber Engineering</em>.
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Konferensbidrag (refereegranskat)abstract
- In the present work the change in natural frequencies, damping and mode shapes of a prefabricated timber floor element have been investigated when it was integrated into a building structure. The timber floor element was first subjected to modal testing in laboratory with ungrounded and simply supported boundary conditions, and then in situ at different stages of building construction. The first five natural frequencies, damping ratios and mode shapes of the floor element and the entire floor were extracted and analysed. It may be concluded that the major change in natural frequencies occur as the floor element is coupled to the adjacent elements and when partitions are built in the studied room, the largest effect is on those modes of vibration that largely are constrained in their movement. Thein situ conditions have a great influence on the damping, which probably depends on the damping characteristics of the supports, but also on the fact that the floor is integrated into the building and interacts with it. There is a slight increase of damping in the floor over the different construction stages and the damping values seem to decrease with ascending mode order. The relative change also seems to decrease with increasing number of storeys built.
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| 17. |
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| 18. |
- Jarnerö, Kirsi
(författare)
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Ljudisolering i trähus : översättning av finsk handbok
- 2007
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Rapport (refereegranskat)abstract
- Syftet med denna handbok är att ge en bakgrund till byggnadsakustiken i trähus med råd och anvisningar om vad man måste tänka på vid projektering och produktion samt exempel på detaljlösningar som i praktiken visat sig fungera bra. Handboken grundar sig på forskning och utveckling vid VTT i Finland och på litteratur om ljudisolering. Trots att det finns nationella skillnader i val av byggnadstekniska lösningar och i bygglagstiftning, ger handboken värdefull information och kunskap om byggnadsakustiska frågor i trähus och exempel på nya lösningar som kan användas även i svenska byggprojekt.
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| 19. |
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| 20. |
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| 21. |
- Jarnerö, Kirsi
(författare)
-
Träbjälklag för långa spännvidder – En förstudie av olika material och konstruktionslösningar
- 2003
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- En ökad användning av trä kräver utveckling av nya byggsystem och byggprodukter. Väl utvecklade byggsystem finns i konkurrerande material som stål och betong för både bostäder och offentliga byggnader, som kontor. För att trä ska kunna konkurrera med betong i bjälklagssystem krävs bland annat att träalternativet ska klara längre spännvidder än det gör idag. En lång spännvidd för bostadsbjälklag är 7-10 m medan den för kontorslokaler är 12 m eller mer. De olika krav som beställare, nyttjare, myndigheter och byggnadsentreprenörer ställer på bjälklag beskrivs och diskuteras. Dimensionering av bjälklag av trä är först och främst ett deformationsproblem och inte ett hållfasthetsproblem. Ju längre spännvidd desto svårare är det att uppfylla nedböjnings-, svikt- och vibrationskrav.
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| 22. |
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| 23. |
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| 24. |
- Jarnerö, Kirsi, et al.
(författare)
-
Vibration properties of a timber floor assessed in laboratory and during building construction
- 2010
-
Ingår i: <em>Proceedings of INTER-NOISE</em>.
-
Konferensbidrag (refereegranskat)abstract
- In the present work the change in natural frequencies, damping and mode shapes of a prefabricated timber floor element have been investigated when it was integrated into a building structure. The timber floor element was first subjected to modal testing in laboratory with ungrounded and simply supported boundary conditions, and then in situ at different stages of building construction. The first five natural frequencies, damping ratios and mode shapes of the floor element and the entire floor were extracted and analysed. It may be concluded that the major change in natural frequencies occur as the floor element is coupled to the adjacent elements and when partitions are built in the studied room, the largest effect is on those modes of vibration that largely are constrained in their movement. The in situ conditions have a great influence on the damping, which depends on the damping characteristics of the supports, but also on the fact that the floor is integrated into the building and interacts with it. There is a slight increase of damping in the floor over the different construction stages and the damping values seem to decrease with ascending mode order.
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| 25. |
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| 26. |
- Jarnerö, Kirsi, et al.
(författare)
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Vibration properties of a timber floor assessed in laboratory and during construction
- 2015
-
Ingår i: Engineering structures. - : Elsevier BV. - 0141-0296 .- 1873-7323. ; 82, s. 44-54
-
Tidskriftsartikel (refereegranskat)abstract
- Natural frequencies, damping ratios and mode shapes of a prefabricated timber floor element have been assessed experimentally in laboratory with different boundary conditions and in situ (in field) at different stages of construction. In laboratory the change in modal parameters was studied with free-free boundary conditions and simply supported on two sides. Three different simply supported tests with changes in boundary conditions were carried out; the floor placed on the support without any fastening or interlayer between support and floor, the floor screwed to the supports and the floor placed on an elastic interlayer between support and floor. The in situ tests were carried out first on the single floor element and then on the entire floor of the room into which the floor element was built in. The damping ratio of the floor increased from 1% to 3% when simply supported in laboratory to approximately 5% when placed upon a polyurethane interlayer (Sylodyn®) in situ, and to approximately 6% when fully integrated in the building. Thus the in situconditions have considerable influence on the damping and the values assessed are very high in comparison with damping values suggested in design codes. Regarding natural frequencies it was concluded that the major change in these occur as the floor element is coupled to the adjacent elements and when partitions are built in the studied room, the largest effect is on those modes of vibration that are largely constrained in their movement.
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| 27. |
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| 28. |
- Jarnerö, Kirsi
(författare)
-
Vibrations in timber floors : Dynamic properties and human perception
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Springiness and vibrations of timber floors are familiar to many as a ‘live’ feelwhen walking on them, especially if living in single family housing with timberframework. Since the building regulations in Sweden changed to performancedependentrequirements in 1994 the use of timber in multifamily housing hasincreased. New timber building systems have been developed and increasedbearing capacity of floors has made it possible to build with longer spans. Thelow mass of timber floors makes them more sensitive to dynamic loading byhuman activities, such as walking, running and jumping, compared to heavyfloors e.g. concrete floors. To improve vibration performance it is possible tochange the structural properties of the floors by increasing mass, stiffness ordamping properties. The most practicable solution is to increase the stiffness.Improved damping is also highly effective, but is difficult estimate and designaccurately since it originates from many sources in the finished building. In thepresent thesis the effects on dynamic properties from increased stiffnesstransverse to the load bearing direction of a floor have been assessed from testsin laboratory. The effect on dynamic performance of a timber floor fromelastic/damping interlayers (polyurethane elastomers) installed in the junctionsbetween walls and floors have been assessed in laboratory and in situ. Also thechange in dynamic properties of an in situ floor has been investigated atdifferent stages of construction and compared with results from laboratory tests.The present criteria for design of timber floors with respect to vibrationperformance were developed at a time when timber floors were mainly used insingle-family housing. The traditional timber joist floors differ in structuralbehaviour from the new types of floors developed recently. The experiencedvibration annoyance by residents in single- and multifamily housing differs asthe source of vibration disturbance and those who become disturbed aredifferent. The changed conditions give cause for a review of present designcriteria. A laboratory and field study on vibration performance was conductedwith questionnaires and dynamic performance measurements. The subjectiveand objective results were correlated and indicators for vibration acceptabilityand annoyance were assessed and new vibration performance criteria andvibration performance classes were suggested.
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| 29. |
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| 30. |
- Johansson, Marie, 1973-, et al.
(författare)
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Building higher with light-weight timber structures - The effect of wind induced vibrations
- 2015
-
Ingår i: INTER-NOISE 2015 - 44th International Congress and Exposition on Noise Control Engineering. - : The Institute of Noise Control Engineering of the USA, Inc..
-
Konferensbidrag (refereegranskat)abstract
- During the last years the interest in multi-storey timber buildings has increased and several medium-to-high-rise buildings with light-weight timber structure have been designed and built. Examples of such are the 8-storey building Limnologen in Växjö, Sweden, the 9-storey Stadthaus in London, UK and being constructed at the moment, the 14-storey building Treet in Bergen, Norway. These are all light-weight and flexible structures which raise questions regarding the wind induced vibrations. For the building in Norway, the calculated vibration properties of the top floor are on the limit of being acceptable according to the ISO 101371 vibration criteria for human comfort. This paper will give a review of building systems for medium-to-high-rise timber buildings. Measured vibration properties for some medium-to-high-rise timber buildings will also be presented. These data have been used for calculating the peak acceleration values for two example buildings for comparison with the ISO standards. An analysis of the acceleration levels for a building with double the height has also been performed showing that designing for wind induced vibrations in higher timber buildings is going to be very important and that more research into this area is needed. © 2015 by ASME.
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| 31. |
- Johansson, Marie, 1973-, et al.
(författare)
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Tall timber buildings : a preliminary study of wind-induced vibrations of a 22-storey building
- 2016
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Ingår i: Proceedings of the World Conference on Timber Engineering (WCTE 2016). - Vienna : Vienna University of Technology. - 9783903039001
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- 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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| 32. |
- Negreira, Juan, et al.
(författare)
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Determination of vibration acceptability and annoyance design indicators for human response to wooden-floor vibrations
- 2014
-
Ingår i: 3rd International Congress on Noise Control Engineering: Improving the World Through Noise Control, INTERNOISE 2014. - 9780909882037
-
Konferensbidrag (refereegranskat)abstract
- The vibrational response of wooden floor systems is an issue that needs to be dealt with more adequately. Notably, studies addressing human response to vibrations are needed in order to better estimate what level of vibrations in dwellings can be seen as acceptable. In this investigation, measurements on five different floors were performed in a laboratory environment at two locations in Sweden. Acceleration measurements were carried out while a person either was walking on a particular floor or was seated in a chair placed there, as the test leader was walking on the floor. These participants filled out a questionnaire regarding their perception and experiencing of the vibrations. Independently of the subjective tests, acceleration measurements were also carried out, using a shaker as excitation source, with the aim of determining the dynamic characteristics of the floors. In addition, static load tests were performed using displacement gauges so as to measure the floor deflections. The ultimate aim was to develop indicators of human response to floor vibrations, specifically those regarding vibration acceptability and vibration annoyance, their being drawn based on relationships between the questionnaire responses obtained and the parameter values determined on the basis of the measurements carried out.
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| 33. |
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| 34. |
- Negreira, Juan, et al.
(författare)
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Psycho-vibratory evaluation of timber floors - Towards the determination of design indicators of vibration acceptability and vibration annoyance
- 2015
-
Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 0022-460X .- 1095-8568. ; 340, s. 383-408
-
Tidskriftsartikel (refereegranskat)abstract
- In timber housing constructions, vibrations can be a nuisance for inhabitants. Notably, the vibrational response of wooden floor systems is an issue in need of being dealt with more adequately in the designing of such buildings. Studies addressing human response to vibrations are needed in order to be able to better estimate what level of vibrations in dwellings can be seen as acceptable. In the present study, measurements on five different wooden floors were performed in a laboratory environment at two locations in Sweden (SP in Växjö and LU in Lund). Acceleration measurements were carried out while a person either was walking on a particular floor or was seated in a chair placed there as the test leader was walking on the floor. These participants filled out a questionnaire regarding their perception and experiencing of the vibrations in question. Independently of the subjective tests, several static and dynamic characteristics of the floors were determined through measurements. The ultimate aim was to develop indicators of human response to floor vibrations, specifically those regarding vibration acceptability and vibration annoyance, their being drawn based on relationships between the questionnaire responses obtained and the parameter values determined on the basis of the measurements carried out. To that end, use was made of multilevel regression. Although the sample of floors tested was small, certain clear trends could be noted. The first eigenfrequency (calculated in accordance with Eurocode 5) and Hu and Chui׳s criterion (calculated from measured quantities) proved to be the best indicators of vibration annoyance, and the Maximum Transient Vibration Value (computed on the basis of the accelerations experienced by the test subjects) to be the best indicator of vibration acceptability.
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| 35. |
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| 36. |
- Olsson, Jörgen, 1975-, et al.
(författare)
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Evaluation of AkuLite measurements of buildings : a comparison between sound pressure stemming from tapping machine and impact ball excitations
- 2015
-
Ingår i: Proceedings of the Forum Wood Building Nordic Conference 2015. - Växjö.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The impact ball has shown to give excitations in close resemblance with the excitation from a human step. However due to practice and practical measurement reasons, it is interesting to use the tapping machine in low-frequency measurements. Here, the two excitation techniques; the tapping machine and the impact ball, are compared in terms of statistical dispersion. In the AkuLite project light weight apartment buildings were measured using a tapping machine and a (Japanese) impact ball in the low frequency range down to 20 Hz. The results showed that the tapping machine gives more narrow/better confidence interval in the test compared to the test using one excitation point together with the impact ball. The t-test of the consistency of the difference between the impact ball and tapping machine for the same measurement objects shows weak correlation, which implies that the results from the tapping machine are not normally possible to be interchanged with impact ball results and vice versa, without using a correction factor.
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| 37. |
- Olsson, Jörgen, 1975-, et al.
(författare)
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Incremental use of FFT as a solution for low BT-product reverberation time measurements
- 2023
-
Ingår i: Applied Acoustics. - : Elsevier Ltd. - 0003-682X .- 1872-910X. ; 203
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Tidskriftsartikel (refereegranskat)abstract
- The limitations in performance of band-pass filters to accurately process rapid decaying signals in lower frequency bands is an obstacle for some measurements within building acoustics. For instance, it would be beneficial to be able to accurately measure reverberation times down to the 20 Hz one-third octave band for impact sound in timber buildings. Here, it is tested whether calculations with FFT with small incremental steps may be a way to achieve discrete frequency time signals with faster performance than traditional band-pass filters. The tests show that incremental FFT gives accurate estimations of the reverberation time corresponding down to 0.1 s at 20 Hz with a spectral resolution of 2 Hz. Using the one-third octave limits it is possible to form approximate one-third octave band results. It is seen that accurate estimations of reverberation time are achievable for BT⩾0.5 (T=0.1 seconds for the 20 Hz one-third octave band) and possibly even lower, if the dynamic range in the interrupted noise signal is sufficient. The higher one-third octave results show to work as well. A disadvantage with the method is that during short reverberation times (0.1 s) there is a severe spectral leakage to the side bands. Also, the method requires higher dynamic range decay signals compared to band-pass filtered signals. If a one-third octave resolution is requested, a dynamic range of 50 dB or greater is preferable. With a coarse resolution of e.g., 10 Hz and having no averaging into one-third octave bands, it is possible to measure short reverberation times (0.1 s) with signals having close to the same dynamic range used in classical band-pass filtered reverberation time measurements. © 2022 The Author(s)
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| 38. |
- Olsson, Jörgen, 1975-, et al.
(författare)
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Incremental use of FFT as a solution to measure short reverberation times in low one-third octave bands
- 2023
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Ingår i: Forum Acusticum Convention of the European Acoustics Association, Torino, 11-15 September 2023. - : European Acoustical Association.
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Konferensbidrag (refereegranskat)abstract
- Measurements of reverberation time is often used to obtain information about sound absorption of rooms within building acoustics. A limitation of the common method used today is the performance of band-pass filters to process rapidly decaying signals in the low frequency range. This occurs when the reverberation time (T) and bandwidth (B) product is less than 16. This is a limitation infor instance multi-story timber buildings where low frequency range, below 50 Hz is of interest for impact sound performance. Here, an alternative method is tested. Using incremental short time steps between each FFT calculation creates “moving average” signals, one for each frequency spectral line. A disadvantage is that the methodrequires a high dynamic range of the interrupted noisesignals, which increases with frequency resolution. Here itis tested to fit in the frequency resolution to the one-thirdoctave band frequency limits with as small errors as possible. It is shown that the dynamic range can be decreased a bit compared to a previously presented version. Two disadvantages with just one spectral line for each third octave band is that the signals are less stable and to produce the different frequency resolutions for each one-third octave requires more calculations.
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| 39. |
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| 40. |
- Olsson, Jörgen, et al.
(författare)
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Low frequency measurements of impact sound performance in light weight timber frame office buildings
- 2012
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Ingår i: Proceedings of EURONOISE 2012. - : European Acoustics Association. - 9788001050132 ; , s. 191-196
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Konferensbidrag (refereegranskat)abstract
- There is little data available of low frequency impact sound response of light weight wooden buildings. The ISO 140-7, 717-2 standards normally used of impact sound is limited down to 50 Hz. The response in low frequency area is of interest for human comfort. In the present work low-frequency impact sound measurements were carried out in two modern office buildings with lightweight timber frame. The purpose was to assess the levels of impact sound transmission below 50 Hz in these construction types. The low frequency impact sound levels are compared to the higher. Both the tapping machine and the impact ball are used for excitation. It is seen that the present constructions have their highest levels below or close to 50 Hz when excited by the impact ball. From the office rooms sharing joist floor with corridor there is seen increased levels of low frequency impact sound. Up to 10-15 dB higher impact sound was detected compared to room with joist floor separated from corridor.
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| 41. |
- Olsson, Jörgen, 1975-, et al.
(författare)
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Low frequency sound pressure fields in small rooms in wooden buildings with dense and sparse joist floor spacings
- 2015
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Ingår i: Proceedings of the Internoise 2015 conference. - : The Institute of Noise Control Engineering of the USA. ; , s. 652-663
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Konferensbidrag (refereegranskat)abstract
- Using wood as the main construction material is a potential solution to achieve sustainable buildings. Previous research has shown that frequencies below 50 Hz are of significant importance for the perception of impact sound by residents living in multi-story buildings having light weight wooden frameworks. The standards used for impact sound measurements today are developed for diffuse fields above 50 Hz. For instance due to requirements concerning wall reflections, these methods are not applicable for low frequencies within small rooms. To improve measurement methods, it is important to know the nature of the full sound distribution in small rooms having wooden joist floors. Here, impact sound measurements with microphone arrays are made in two small office rooms having the same dimensions. The rooms represent two extremes in design of joist floors; one with closely spaced wood joists and the other with widely spaced joists. An impact ball is used for excitation the room being measured from the room above. The results show that there are significant variations in the sound pressure, especially in the vertical direction. Here, measurement techniques of impact sound in the low frequency range in small rooms in wooden buildings are evaluated and potential improvements are proposed.
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| 42. |
- Rosenkilde, Anders, et al.
(författare)
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Flervåningshus med trästomme – Uppföljning av Kv Limnologen och Kv Rya, Rydebäck
- 2008
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Rapport (refereegranskat)abstract
- The aim has been to observe, evaluate and as far as possible support two large wooden multi-storey building projects. The building projects have been observed during the different stages of the building process. The first building project is Limnologen in Växjö, that includes four seven-storey residential buildings, of which the first building has been observed from the early stages of planning to finished erection of the wooden frame. The second building project is located in Rydebäck close to Helsingborg. It comprises several buildings, of which a five-storey residential building was observed from finished planning to user stage. Equipment was installed in Rydebäck to measure the climate in several locations in the construction and the strain in the tie-rods that tie the building to the foundation. The results are presented in this report and also in abundant photos and comprehensive separate reports with further technical data. In addition, the great experiences achieved by the involved participants will most likely influence, and have partially already influenced, future larger wooden frame building projects. It is concluded that it is possible to carry out large-scale wooden frame building projects. The continued challenge is to improve especially the building process with lean thinking strategies. There are also several details that have to be improved further, e g improved sound insulation at low frequencies (20-200 Hz). Efforts are also needed to make it easier for building system suppliers and designing consultants to design correctly with regard to fire requirements and to increase compatibility in fire safety issues between participants on the market and within the country.
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| 43. |
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| 44. |
- Sjökvist, Lars-Göran, et al.
(författare)
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Subjective response to vibrations in timber floors
- 2011
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Ingår i: Proceedings of Forum Acusticum 2011. - : Danish Acoustical Society.
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Konferensbidrag (refereegranskat)abstract
- For timber floors in residential buildings the vibrations can be annoying. In order to have a better understanding of the expected level of vibrations, more studies are needed where human response to vibration is evaluated. In the present study five wooden floors have been built in a laboratory hall. Test persons evaluated the vibrations for two situations, first by own walking on the floor and thereafter by sitting on a chair while a second person walked. The floors deflection and input accelerans were measured. The results from the measurements are compared to the test person’s answers. This test indicates that the first eigenfrequency is a better indicator for vibration discomfort than the broadband input accelerance.
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| 45. |
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| 46. |
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| 47. |
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| 48. |
- Ågren, Anders, et al.
(författare)
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Flanking transmission in light weight timber houses with elastic flanking isolators
- 2012
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Ingår i: 41st International Congress and Exposition on Noise Control Engineering, INTER-NOISE 2012. - : AtlasBooks / Institute of Noise Control Engineerin. ; , s. 2289-2300, s. 2289-2300
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Konferensbidrag (refereegranskat)abstract
- There is a strong trend to industrially produce multi-storey light weight timber based houses. This concept allows the buildings to be manufactured to a more or less prefabricated extent. Most common types are volume/room modules or flat wall and floor modules. When assembling the modules at the building site, elastomer isolators are used in several constructions to reduce flanking transmission. The sound insulation demands in the Nordic countries are relatively high and therefore the flanking transmission must be well controlled, elastomer isolators is one choice. Decoupled radiation isolated walls is another. There are though no working studies or mathematical models of the performance of these isolators. They are only treated as simple mass-springs systems that operate vertically. In this paper there is a first approach of an analysis of the structure borne sound isolating performance of elastomer isolators that are separating floors and walls. The performance dependence of structure type is also presented. An empirically based regression model of the insertion loss is derived. The model will be based on measurements of more than ten field installations. In this paper the first three are presented. A goal is that the model can be used for input in future SEN prediction models for modeling of sound insulation.
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| 49. |
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