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42 records – page 1 of 5.

Innovative solutions to improved sound insulation of CLT floors

https://research.thinkwood.com/en/permalink/catalogue3339
Year of Publication
2023
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Ljunggren, Fredrik
Organization
Luleå University of Technology
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Sound Insulation
Low Frequencies
Impact Sound
Compressed Wood
Research Status
Complete
Series
Developments in the Built Environment
Summary
Building with cross laminated timber (CLT) has gain increased interest over the last years, but in common to other wood-based building systems, inadequate low-frequency sound insulation is seen as a problem. This paper deals with two methods to improve the sound insulation of CLT panels, normally made from spruce: 1) heavy CLT, introducing compressed, i.e. densified, spruce as well as alternative wood species, and 2) elastic layer based upon shear motion. In addition to a series of laboratory measurements, a full-scale CLT floor made of two 60 mm birch panels with a 12 mm elastic layer in between was tested in a two-room test mock-up. The results from the acoustical measurements showed that the floor has about 7 dB greater airborne and impact sound insulation for one-third octave bands, 50–3150 Hz, compared to a standard CLT floor of the same total height.
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Effects of building height on the sound transmission in cross-laminated timber Buildings – Airborne sound insulation

https://research.thinkwood.com/en/permalink/catalogue3342
Year of Publication
2023
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Author
Nilsson, Erik
Ménard, Sylvain
Bard, Delphine
Hagberg, Klas
Organization
University of Québec at Chicoutimi
Publisher
Elsevier
Year of Publication
2023
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Topic
Acoustics and Vibration
Keywords
Building Height
Viscoelastic Interlayer
Airborne Sound Insulation
Research Status
Complete
Series
Building and Environment
Summary
Buildings constructed with cross-laminated timber (CLT) are increasing in interest in several countries. Since CLT is a sustainable product, it can help the building industry to reduce greenhouse gas emissions. Furthermore, buildings constructed with CLT are increasing in building height, thereby increasing the load on the junctions and structural building elements further down in the building. Several studies have investigated how the load impacts the sound transmission between apartments. The majority found that an increasing load could have a negative effect on the vertical sound insulation. However, the findings are limited to a few measurements or building elements, and the studies only investigate junctions with resilient interlayers. This article aims to investigate if the building height, and thereby the load, affect the vertical airborne sound insulation between apartments on different stories in different cross-laminated timber buildings, with or without the presence of viscoelastic interlayers, and to quantify the effect. Four CLT buildings with different building systems, building heights, and the presence of viscoelastic interlayers in the junctions were measured. The airborne sound insulation between different apartment rooms was measured vertically for stories on the lower and higher levels. The difference in airborne sound insulation was calculated separately for each building, and the measurements indicate that the vertical airborne sound insulation reduces further down in the buildings. Therefore, results show that increasing load, by an increasing number of stories, has a negative effect on the vertical airborne sound insulation.
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Experimental and numerical modal analysis of a cross laminated timber floor system in different construction states

https://research.thinkwood.com/en/permalink/catalogue3145
Year of Publication
2022
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Kawrza, Michael
Furtmüller, Thomas
Adam, Christoph
Organization
University of Innsbruck
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Floor Construction
Footfall Sound Insulation
Modal Analysis
Optimization
Research Status
Complete
Series
Construction and Building Materials
Summary
This paper addresses the vibration characteristics of a cross laminated timber (CLT) floor in a residential building during three construction states. Experimental modal analyses are carried out on the blank CLT slab, on the slab with added drywall ceiling, and on the slab with drywall ceiling and added floating screed. A reliable numerical model of the system is created with the means of a finite element model updating procedure. This model shows that some experimentally determined modes can be attributed to the dynamic interaction with the shaker used for excitation during the tests. In the finite element model, this effect can subsequently be eliminated. Based on the validated numerical model, the impact of various parameters of the floor construction on the low-frequency footfall sound insulation is investigated.
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Evaluating Laboratory Measurements for Sound Insulation of Cross-Laminated Timber (CLT) Floors: Configurations in Lightweight Buildings

https://research.thinkwood.com/en/permalink/catalogue3157
Year of Publication
2022
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Vardaxis, Nikolaos-Georgios
Hagberg, Delphine Bard
Dahlström, Jessica
Organization
Lund University
Editor
Park, Junhong
Publisher
MDPI
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Airborne Sound
Impact Noise
Sound Insulation
Research Status
Complete
Series
Applied Sciences
Summary
Cross-laminated timber (CLT) floors with supplementary layers or floating floors comprise a common solution in new multistory timber structures. However, bare CLT components provide poor sound insulation, especially in low frequencies during structure-borne sound propagation. Thus, floor configurations in wooden buildings deploy more layers for improved acoustic behavior. Twelve contemporary CLT floors were analyzed after laboratory measurements of airborne sound reduction and impact sound transmission utilizing the following indicators: Rw, Rw, 100, Rw, 50, Ln,w, Ln,w,100, and Ln,w,50 (per ISO 10140, ISO 717). An increase in sound insulation was achieved thanks to added total mass and thickness, testing layers of the following: elastic mat for vibration isolation, wool insulation, gypsum boards, plywood, concrete screed, and wooden parquet floor. The results indicate that multilayered CLT floors can provide improvements of up to 22 dB for airborne sound and 32 dB for impact sound indicators compared with the bare CLT slab. Floating floor configurations with dry floor solutions (concrete screed) and wooden parquet floors stand out as the optimal cases. The parquet floor provides a 1–2 dB improvement only for impact sound indicators in floating floor setups (or higher in three cases).
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Simulation of impact force generated by an ISO tapping machine on a wooden slab using explicit dynamics analysis

https://research.thinkwood.com/en/permalink/catalogue3256
Year of Publication
2022
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Lietzén, Jesse
Sormunen, Juho
Pajunen, Sami
Kylliäinen, Mikko
Organization
Tampere University
Publisher
Elsevier
Year of Publication
2022
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Impact Sound Insulation
Impact Force
FEM
Explicit Time Integration
LS-DYNA
Tapping Machine
Wooden Floor
Research Status
Complete
Series
Engineering Structures
Summary
Application of simulation tools to compute impact sound insulation properties of wooden floors has raised interests in recent decades. To achieve accurate results from the prediction models, information from force excitation generated by impact sound sources is required. The purpose of our study was to present a validated procedure to determine the non-linear impact force excitation generated by an ISO tapping machine. The method comprised use of finite element method (FEM) and explicit time integration to compute impact force pulse generated by a hammer of the tapping machine. With a post-processing procedure, the force pulses can be converted to present point forces describing the continuous operation of the tapping machine on the floor. To demonstrate the applicability of the method, the finite element model was applied to imitate an experimental situation on a cross-laminated timber (CLT) slab. The model validation showed that the computational model closely predicts the force pulse generated on the CLT slab. Findings from a sensitivity analysis revealed that local properties of the slab were the most important to the simulated impact force pulse. The findings of the analysis are helpful for those developing simulation tools to compute the impact force generated by the tapping machine on wooden floors.
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Cyclic Response of Insulated Steel Angle Brackets Used for Cross-Laminated Timber Connections

https://research.thinkwood.com/en/permalink/catalogue2765
Year of Publication
2021
Topic
Seismic
Acoustics and Vibration
Connections
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Author
Kržan, Meta
Azinovic, Boris
Publisher
Springer
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Floors
Topic
Seismic
Acoustics and Vibration
Connections
Keywords
Angle Bracket
Sound Insulation
Insulation
Monotonic Test
Cyclic Tests
Wall-to-Floor
Stiffness
Load Bearing Capacity
Shear
Tensile
Research Status
Complete
Series
European Journal of Wood and Wood Products
Summary
In cross-laminated timber (CLT) buildings, in order to reduce the disturbing transmission of sound over the flanking parts, special insulation layers are used between the CLT walls and slabs, together with insulated angle-bracket connections. However, the influence of such CLT connections and insulation layers on the seismic resistance of CLT structures has not yet been studied. In this paper, experimental investigation on CLT panels installed on insulation bedding and fastened to the CLT floor using an innovative, insulated, steel angle bracket, are presented. The novelty of the investigated angle-bracket connection is, in addition to the sound insulation, its resistance to both shear as well as uplift forces as it is intended to be used instead of traditional angle brackets and hold-down connections to simplify the construction. Therefore, monotonic and cyclic tests on the CLT wall-to-floor connections were performed in shear and tensile/compressive load direction. Specimens with and without insulation under the angle bracket and between the CLT panels were studied and compared. Tests of insulated specimens have proved that the insulation has a marginal influence on the load-bearing capacity; however, it significantly influences the stiffness characteristics. In general, the experiments have shown that the connection could also be used for seismic resistant CLT structures, although some minor improvements should be made.
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The influence of flexible sound insulation layers on the seismic performance of cross laminated timber walls

https://research.thinkwood.com/en/permalink/catalogue2882
Year of Publication
2021
Topic
Mechanical Properties
Seismic
Material
CLT (Cross-Laminated Timber)
Application
Walls
Author
Azinovic, Boris
Pazlar, Tomaž
Kržan, Meta
Organization
ZAG Ljubljana
Publisher
Elsevier
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Walls
Topic
Mechanical Properties
Seismic
Keywords
Angle Bracket
Elastomer Sound Insulation
Racking Test
Lateral Load-bearing Capacity
Research Status
Complete
Series
Journal of Building Engineering
Summary
This paper presents the results of an experimental campaign investigating the seismic behaviour of full-size cross laminated timber (CLT) wall systems with sound-insulated shear-tension angle brackets. The main aim of the study was to investigate the influence of more and less flexible soundproofing bedding under the CLT wall. The paper shows a comparison of lateral load-bearing capacity, displacement capacity, ductility and stiffness obtained from racking tests on uninsulated specimens and specimens with various types of bedding insulation and levels of vertical load. Moreover, an analytical procedure to estimate the lateral load-displacement response of CLT walls with bedding insulation is proposed. This model is verified by direct comparison to the experimentally determined lateral load-displacement backbone curves. The results show that the elastomeric bedding does not have a significant effect on the bearing capacity of the wall system tested, but it reduces the stiffness and increases the displacement capacity. Due to the large decrease in stiffness, the insulation causes an overall reduction in ductility. The analytical estimation proposed was able to capture the reduction in lateral stiffness and adequately predict the load-bearing capacity.
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The Influence of Floor Layering on Airborne Sound Insulation and Impact Noise Reduction: A Study on Cross Laminated Timber (CLT) Structures

https://research.thinkwood.com/en/permalink/catalogue2894
Year of Publication
2021
Topic
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Application
Floors
Author
Bettarello, Federica
Gasparella, Andrea
Caniato, Marco
Organization
University of Trieste
Free University of Bozen
Editor
Piana, Edoardo
Bonfiglio, Paolo
Rychtarikova, Monika
Publisher
MDPI
Year of Publication
2021
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Floors
Topic
Acoustics and Vibration
Keywords
Impact Noise Transmission
Sound Insulation
Rubber Ball
Tapping Machine
Sustainable
Research Status
Complete
Series
Applied Sciences
Summary
The use of timber constructions recently increased. In particular, Cross Laminated Timber floors are often used in multi-story buildings. The development of standardization processes, product testing, design of details and joints, the speed of construction, and the advantages of eco-sustainability are the main reasons why these structures play a paramount role on the international building scene. However, for further developments, it is essential to investigate sound insulation properties, in order to meet the requirements of indoor comfort and comply with current building regulations. This work presents the results obtained by in field measurements developed using different sound sources (tapping machine, impact rubber ball, and airborne dodecahedral speaker) on Cross Laminated Timber floors, changing different sound insulation layering (suspended ceiling and floating floors). Results clearly show that the influence on noise reduction caused by different layering stimulated by diverse noise source is not constant and furthermore that no available analytical model is able to correctly predict Cross Laminated Timber floors acoustic performances.
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Calculation of Sound Insulation for Hybrid CLT Fabricated with Lumber and LVL and Comparison with Experimental Data

https://research.thinkwood.com/en/permalink/catalogue2216
Year of Publication
2019
Topic
Acoustics and Vibration
Material
LVL (Laminated Veneer Lumber)
CLT (Cross-Laminated Timber)
Author
Ju, Zehui
Zhang, Haiyang
Zhan, Tianyi
Hong, Lu
Lin, Yangfan
Lu, Xiaoning
Organization
Nanjing Forestry University
Publisher
EDP Sciences
Year of Publication
2019
Format
Conference Paper
Material
LVL (Laminated Veneer Lumber)
CLT (Cross-Laminated Timber)
Topic
Acoustics and Vibration
Keywords
Sound Insulation
Research Status
Complete
Series
MATEC Web of Conferences
Summary
The insulated predictions were carried out for LVL, CLT and HCLT in order to evaluate their sound properties, in which the theoretical value of sound insulation was predicted by regarding the substances in wood cell wall as equivalence to specific medium based on Biot model, and the wood anatomical characteristics, such as the length and diameter of tracheid, diameter of pit, and porosity, were taken into account for determining the equivalent density and bulk modulus of elasticity of wood cell wall. By comparing the tested and predicted values of sound insulation, the conclusion were drawn as follows: the predicted values of sound insulation were significantly correlated with the tested values for LVL, CLT and HCLT. As for Masson pine and Southern pine, the adjacent of earlywood and latewood was considered as sandwich structure for the calculation of sound insulation. Meanwhile, the bonding interface was creatively introduced to improve the accuracy of sound insulation prediction. The transfer function involved in sound insulation prediction provide an effective method to characterize the sound insulation volume of wood composite in construction and decoration areas.
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The ASTC Ratings of Mid-rise Wood Constructions Using CertainTeed SilentFX® QuickCut Gypsum Board [3rd edition]

https://research.thinkwood.com/en/permalink/catalogue2615
Year of Publication
2019
Topic
Design and Systems
Acoustics and Vibration
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Walls
Floors
Author
Mahn, Jeffrey
Organization
National Research Council of Canada. Construction
Publisher
National Research Council of Canada. Construction
Year of Publication
2019
Format
Report
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Walls
Floors
Topic
Design and Systems
Acoustics and Vibration
Keywords
Mid-Rise
Residential Buildings
Acoustic Performance
Sound Insulation
Gypsum
Fiberglass Insulation
Research Status
Complete
Summary
The 2015 edition of the National Building Code of Canada (NBCC) includes significant changes to the acoustic requirements for residential constructions. The 2015 edition defines the acoustic requirements in terms of the Apparent Sound Transmission Class (ASTC) rating which includes contributions from flanking transmission and therefore is a better descriptor of how well the sound insulation of a building will actually protect the inhabitants of the building from unwanted noise than the STC rating which was used in earlier editions of the NBCC. The 2015 NBCC requires an ASTC rating = 47 for constructions between dwelling units. The ASTC rating that a construction will achieve depends on the design of the building elements including the gypsum board, the framing and the thermal insulation as well as the design of the junctions between the building elements. Changes to the building elements or the junctions will change the ASTC rating. Fifty five examples of the calculation of the ASTC rating for typical mid-rise wood constructions (single and triple staggered wood stud walls and floors constructed of I-joists) with 15.9 mm (5/8”) SilentFX® QuickCut gypsum board, 15.9 mm CertainTeed Type X gypsum board and CertainTeed Sustainable fiberglass insulation are presented. All of the constructions shown in the examples have an ASTC rating which is greater than 47. In addition to the examples for mid-rise wood framing, an example using 15.9 mm SilentFX® QuickCut gypsum board as a lining on a cross laminated timber (CLT) construction is also presented.
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42 records – page 1 of 5.