Floating Floor System Research Articles

Impact sound insulation of cross-laminated timber/massive wood floor constructions: Collection of laboratory measurements and result evaluation

Wooden building systems, including cross-laminated timber elements, are becoming more common. The last few years have seen new developments and documentation of innovative types of cross-laminated timber floor assemblies. Regarding impact sound associated to walking persons, running or jumping children, such floor assemblies can be regarded as a weak part. So far, there are no reliable standardized calculation models available, for prediction of impact sound in the entire frequency range. Therefore the design is always based upon previous experiences and available measurements. This article presents the results of a number of well controlled sound insulation measurements of cross-laminated timber/massive wood floor constructions conducted in laboratories. The collection of data and results analysis highlight some basic phenomena. For instance, how structural differences related to the grouping of the constructions change the frequency distribution of the impact sound level and the single number quantities. Another significant result is the influence of the dynamic stiffness of the resilient interlayer of floating floor systems and the mass per unit area of the floors. Based on this analysis, the aim is to identify similarities and carry out simplifications. The data will be further processed and used in the development of prediction models and optimization process of cross-laminated timber floor assemblies.

Effect of Changes in Temperature on Resilient Materials Dynamic Stiffness and Floor Impact Sound

Floor impact sound is one noise in apartment houses that cannot be avoided. In order to reduce floor impact sound, a floating floor system using resilient materials has been generally applied. Floor impact sound insulation performance of the floating floor system is dependent on the physical property (dynamic stiffness) of resilient materials. This study investigated the effect of temperature changes on resilient materials used in the floating floor system and on dynamic stiffness. Ethylene vinyl acetate (EVA) and expanded polystyrene (EPS) were used as resilient materials, and dynamic stiffness was measured during three stages of temperature change condition. The measurement result showed that as the temperature decreased, dynamic stiffness also increased. This study also analyzed the effect of changes in outdoor temperature on the heavyweight impact sound level with respect to concrete buildings with wall slabs. The floor impact sound level tended to increase during the winter season, when the outdoor temperature was low.

Evaluation of the long-term sound reduction performance of resilient materials in floating floor systems

Building multi-dwelling units is one of the practical engineering solutions to housing shortage in urban areas with high population density. However, noise from upstairs is a major issue. The use of resilient materials in floating floor structures is recognized as an effective method to reduce such noise. In general, soft materials are considered as better resilient materials due to their superior performance in impact sound reduction. However, it is often overlooked that the sound reduction performance of soft resilient materials is susceptible to being degraded over time when subjected to a long-term load. In this study, the long-term performance of eight resilient materials is evaluated by monitoring their dynamic stiffness for 270 days under the two sustained load conditions: 250N and 500N. According to the experimental study, the dynamic stiffness increases consistently with loading time for all resilient materials. This leads to a decrease in the sound reduction performance. More rapid reduction in the dynamic stiffness and hence in the sound reduction performance is observed when a larger sustained load is applied. A greater decrease in the sound reduction performance is found in soft resilient materials.

공동주택 바닥완충재의 재하시간에 따른 손실계수 변화 및 환경조건에 따른 장기 처짐 평가

Installing damping layer in the floating floor system is a good way to reduce noises transferred from the houses above so that a number of researchers have studied on the damping materials. This research effort focused especially on the loss factor and deflection of floor sound reduction materials. The experimental program was divided into three sections: the loss factor, deflection of damping materials included in the floating floor system, and the deflection of damping materials submerged completely. Three main parameters were considered in the experimental investigation: the weight of load, the eight types of damping materials and loading periods. Specifically, this experimental test was intended to evaluate the loss factor of damping materials changed subjected to long-term load and also the effect when casting lightweight concrete and finishing mortar and submerged completely throughout the comparative evaluation of deflection of damping materials. The results indicated the loss factor of damping materials was changed time depending subjected to load in the several specimens and flowing the mortar in the damping materials affected their deflections but the submergence of specimens wasn't related to the deflection. Finally, this research results would be valuable references for predicting the noises causing from the upstairs or nearby in the apartment houses.

Time-depending performance of resilient layers under floating floors

In the floating floor system the performance of resilient layers, in terms of impact sound pressure level reduction, is of paramount importance. In the present study in order to evaluate the time-depending performances, a comprehensive characterization of twenty different layers was carried out, evaluating dynamic stiffness, compressibility and compressive creep. The aim of this work was to find out a possible correlation among these parameters and the effect of service time on mechanical and acoustical properties. Results indicated that a general rule couldn’t be defined. Furthermore, the presence of a coating, as well as different density and/or contact shape, has proved to influence the final acoustical performances.

뜬바닥구조의 균열강도 평가

이 연구에서는 층간소음을 억제하기 위하여 사용되는 뜬바닥구조의 구조거동을 실험을 통하여 평가하였다. 최근 층간소음을 억제하기 위하여 연질의 완충재가 사용되며, 이로 인하여 마감모르타르나 기포콘크리트에 균열이 발생할 가능성이 높아지고 있다. 이 연구에서는 완충재의 강성, 하중가력 위치, 바닥 구성층을 변수로 하는 16개의 2방향 뜬바닥구조를 실험하였다. 실험에 의하면 완충재의 강성은 뜬바닥구조의 균열강도에 큰 영향을 미치며 완충재의 할선계수가 0.2MPa인 경우에 낮은 강도에서 균열이 발생하였다. 또한 슬래브의 단부나 모서리에 하중이 가력될 경우에 균열강도가 감소하였다. 뜬바닥구조를 이루고 있는 마감모르타르는 균열강도에 영향을 주었지만 기포콘크리트는 균열강도에 영향을 주지 않았다. This paper reports the test results of the floating floor system used to reduce the floor noise of apartment buildings. Recently, many soft resilient materials placing between the reinforced concrete slab and finishing mortar are used. The resilient material should not only reduce the floor impact sound vibration from the floor but also support the load on the floor. Thus, even if soft resilient materials satisfy the maximum limitation of light-weight impact sound and heavy-weight impact sound, these materials may not support the load on the floor. The experimental program involved conducting sixteen sound insulation floating floor specimens. Three main parameters were considered in the experimental investigation: resilient materials, loading location, and layers of floor. Experimental results indicated that the stiffness of resilient material significantly influenced on the structural behavior of floating floor system. In addition, the deflection of the floating concrete floor loaded at the side or coner of the specimen was greater than that of the floor loaded at the center of the specimen. However, the aerated concrete did not effect on the cracking strength of floating floor system.

The impact of CrossFit training—Weight drops on floating floors

CrossFit training is a popular fitness training method. Some facilities install lightweight plywood floating floor systems as a quick, inexpensive method to mitigate impact generated noise and vibration into adjoining spaces. Part of the CrossFit training regimen involves lifting significant weight overhead, and then dropping the weight on the floor. The energy transferred to the floor system can cause severe damage to floor surfaces and structures; and, when using a lightweight floating floor system, even the isolators can be damaged. This paper describes a spreadsheet based analytical model being used to study the effects of such impacts on various floor systems. This study is a prelude to experiments that will be performed on a full scale model test floor. The results of those experiments will be used to verify the model so that it can be used as a design tool for recommending solutions for mitigating the noise and vibration in adjoining spaces due to floor impact problems. Also discussed in this paper are the qualitative results of some preliminary tests performed in order to better understand the mechanics of impacts on floating floor assemblies.

Effects of vibration characteristics on the walking discomfort of floating floors on concrete slabs.

In the present study, the vibration characteristics of floating floor systems and the discomfort in walking upon them have been studied in concrete slab structures through mock-up floors experiments. Seven types of floor systems, with panels of various sizes and supporting beams with different joist spacings, were constructed based on actual conditions. For the vibration measurement, an ISO rubber ball dropped from a height of 20 cm was used as an impact source to reproduce human walking. The vibration characteristics were evaluated by calculating the vibration acceleration values and the autocorrelation function parameters for the floor structures. Finally, a human walking experiment was conducted to investigate subjective responses to the vibration characteristics of floating floors. From the results, it was found that the vibration acceleration values and walking discomfort varied with the supporting conditions of the floors and that these were highly correlated with each other. It was also found that more than 75% of subjects accepted the floors when the vibration value of the floor in terms of vibration does value (VDV) is below 4.8 ms(-1.75). In addition, a practical regression of the VDV was obtained and design guidelines for floating floors were suggested.

Experimental and numerical analysis of floating floor resonance and its effect on impact sound transmission

This paper is concerned with the analysis of the dependence of low frequency impact sound transmission through floating floor systems on in situ matched resonances. The evidence for the floating floor matched resonances has been found previously considering laboratory and numerical tests for one concrete slab and floating floor with varying resilient layers. In the present paper, considering laboratory and field tests for concrete slabs and floating floors with different plan configurations, this evidence is strengthened as differences between laboratory and field measurements of the impact sound level were negligible for the bare concrete slab but not with the floating floor installed. These results were also confirmed numerically. The analysis indicates that the dependence of low frequency impact sound transmission through floating floor systems on in situ matched resonances should be considered in addition to the conventional single degree of freedom models in order to improve accuracy.

Vibro-acoustic characteristics of floating floor system: The influence of frequency-matched resonance on low frequency impact sound

The low frequency vibro-acoustic characteristics of a massive floating floor with continuous resilient layer are investigated with experimental measurements and numerical simulations using a hybrid FEA–SEA method. The results of the study indicate the occurrence of the in situ resonance of the floating floor system, which could be explained by the frequency matching between bending modes of the floating plate and the vibration isolator. The in situ frequency-matched resonance is considered to result in a sharp rise of the low frequency transmissibility of the vibration isolator and the impact sound. The difference between the in situ and the apparent natural frequency of the vibration isolator is assumed to be due to a reduced mass behavior of the floating floor in association with the base floor. It is inferred in the present work that contributing factors in the in situ frequency-matched resonance such as floating plate dimensions, elastic properties of the plate, and the location of an impact might affect the conventional regime of the single degree-of-freedom vibration isolation model for floating floors. The influence of floating plate dimensions on the occurrence of the in situ frequency-matched resonance might be considered as one of the factors affecting the differences in the low frequency impact sound of massive floating floors between laboratory and field measurements.

Effects of upper surface layers on the vibration characteristics of floating floor systems in concrete slab structures

The effect of materials with supporting conditions on the vibration characteristics of the floating floor systems have been studied in concrete slab structures. Total 10 types of floor systems which have various sizes of panels and supporting beams with different joints were made based on actual conditions. In the measurement of vibration, ISO rubber ball was used as an impact source in order to reproduce human walking. The vibration characteristics were evaluated through calculating the vibration dose value (VDV) and autocorrelation function (ACF) parameters for the vibrations of the floor surface layers. Finally, a human walking experiment was conducted to investigate the subjective responses to the effect of vibration characteristics of the floating floors. As results, the correlation coefficients between physical parameters and subjective responses were derived and a perception model was obtained.

A study on the thermal conductivity of resilient materials

The floor system of apartments must have a certain level of floor impact sound performance (light-weight impact sound is 58 dB or less, heavy-weight impact sound is 50 dB or less), and comply with the building energy code to prevent energy loss in residential buildings in Korea. In this study, expanded polystyrene (EPS), expanded polypropylene (EPP), ethylene-vinyl acetate copolymer (EVA), polyethylene (PE) and urethane foam, which are widely used in Korea as resilient materials for floating floor system of apartments, were measured. Their thermal conductivity and apparent density were measured to analyze their thermal properties and their relation was analyzed by material. In case of resilient materials made of EPS and EPP, thermal conductivity tended to decrease as apparent density increased, whereas in case of resilient materials made of EVA and PE, as apparent density increased, thermal conductivity tended to increase as well.

Control of radiated noise from a ship’s cabin floor using a floating floor

In order to develop the noise control design for a ship's cabin, a series of acoustic tests were carried out in a large scale noise test facilities with two reverberation rooms and deckhouse mock-up. From the tests, it was found that the combined noise level of a cabin was dominated by the radiated noise from the floor structure, which is a combination of a stiffened steel deck and deck covering. In this paper, the dynamic characteristics of floor structure are firstly identified through the structure-borne noise transmission test in the deckhouse mock-up. Based on the result, multi-layer floating floor systems were applied on the steel deck to reduce the radiated noise from the floor structure. Before the application, numerical simulations using assumed modes and structure-borne noise transmission tests are carried out for the floating floor itself to extract the optimum structure. Finally, the considered floating floor systems were applied in the cabin of deckhouse mock-up and the cabin noise reductions are compared. Through a series of numerical simulations and structure-borne noise transmission tests, it is found that the cabin noise reduction of a multi-layer floating floor can be greatly improved over the entire frequency range if the visco-elastic deck covering is installed between the steel deck and the mineral wool of floating floor

Development of thermoacoustic floating floors for use between parking and dwellings

The French thermal regulation (RT2005) is favoring thermal floating floor between spaces such as parking or stores, and dwelling units. However, these solutions do not fulfill the French acoustic regulation with regards to airborne noise. This paper discusses the development of solutions allowing fulfilling both the thermal and the acoustic regulation. To achieve this goal, a mixed approach combining measurements and numerical predictions is used. Furthermore, the laboratory characterization of such floating systems usually involves a concrete base floor 140 mm in thickness (following the NF EN 140‐8 standard) and a floating concrete layer 40 mm in thickness. However, in situ the concrete base floor as well as the floating concrete layer can be thicker. Therefore, some laboratory measurements are performed on a thermal floating floor system combining a 200 mm thick concrete base floor, a thermal insulation layer (polystyrene or polyurethane based foam for example) and a 60 mm thick floating concrete layer. The prediction method shows that this type of thermal floating systems is not acceptable with respect to the acoustic regulation. The behaviour of such multilayered systems is investigated using a wave approach based prediction tool in order to develop solutions allowing fulfilling the acoustic regulation.

Willmott Dixon Isolates Hereford College Technology Block with Kinetics RIM-C Floating Floor System

Willmott Dixon Isolates Hereford College Technology Block with Kinetics RIM-C Floating Floor System

Laboratory Sound Insulation Measurements of Improved Timber Floor Constructions: A Parametric Survey

An extensive measurement survey of timber floor constructions has been carried out by the acoustics laboratory of the Belgian Building Research Institute [1]. The basis of this study was the airborne and structure-borne sound insulation measured on a bare joist floor with OSB (Oriented Strand Board) sub floor. By adding different floor toppings and gypsum board ceilings to the basic floor construction, gradual improvements were recorded. A large number of floors are evaluated in the laboratory and formed a database for parametric studies. Improvements due to cavity absorption, floating floors and suspended ceilings were quantified and ranked by effectiveness. Measurement results revealed remarkable differences between floating floor systems. In addition, sound insulation measurements have been performed on joist floors with concrete toppings. The so-called mixed concrete-timber floors provide a higher mechanical resistance. The effect of the bonding and topping type on the airborne and structure borne sound insulation has been examined in the laboratory. The results of this additional research are briefly compared to traditional floor systems and compared with the (future) Belgian standard values. An overall evaluation of the acoustic relevance of timber floor partitions in and between dwellings is also made.

Floor impact noise reduction in ship cabins by means of a floating floor

Floating floors are widely used to reduce the floor impact noise in ship cabins as well as in multi-dwelling buildings. The most common material for impact absorption in floating floor structure is mineral wool, where high density and sufficient thickness is also needed for fire-resistant requirement in ships. For proper design of floating floors, it is essential to understand how the performance of floating floor is affected by the design parameters such as changes of the mineral wool thickness, density, fiber direction and the use of viscoelastic layer. In this paper, noise reduction performance of the floating floor for use in cruise ship cabin is studied. A mock-up is built by using 6 mm steel plate, and two identical cabins are made of 25 mm sandwich panel inside the steel structure. Various floating floor systems are tested by employing the mock-up. The measurements show that viscoelastic layer is effective when it is used to form a constrained layer. However, viscoelastic layer becomes insignificant when mineral wool is present. It is found that impact noise becomes quieter by 7 dB when fiber direction of the mineral wool is changed from vertical to horizontal, and increasing density of mineral wool from 140 kg/m 3 to 240 kg/m 3 results in an increase of 9 dB. It is also observed that floor SBN (Structure-Borne Noise) is greater than side wall SBN by 10-15 dB up to 2000 Hz, which means that side wall SBN can be neglected in evaluating floor impact noise of ship cabin at frequencies up to 2000 Hz.

뜬바닥구조를 이용한 선실 바닥충격음 저감에 관한 연구

In this paper, floor impact noise reduction in cruise ship cabin is studied. A mock-up is built by using 6t steel plate, and two identical cabins are made where 25t panel is used to construct wall and ceiling inside the steel structure. Various floating floor systems are tested for which normalized impact noise is measured according to ISO 140-7. In addition, floor SBN (Structure-borne Noise) and floor damping are measured to study the effect of floating floor structure. It is shown that VL(Visco-elastic Layer) is more effective when hard plates are added above the VL.

A reduction effect of the floor impact sound after installation of the sound insulation for SMT factory

This study aims to examine some kinds of plans to solve the ploblem of noise and vibration transmitted to adjacent rooms, especially to the downstairs, when using SMT (surface mount technology) equipment. To achive this, a kind of system for preventing noise and vibration was applied, and the effects of sound insulation performance for that were tested and analyzed. To reduce floor impact noise, a floating floor system using a plastic pallet and rubber was applied. The applied plastic pallet is 30 cm wide, 60 cm deep, and 6 cm high and designed to array on a concrete slab. Above this plastic pallet, a 14-cm-thick concrete slab was constructed. After installation of this system the floor impact sound was reduced about 7 dB(A). For more reduction, a ceiling with a 5-cm-thick glass wool and twofold of 0.9-cm-thick plywood was constructed at the directly below downstairs. According to this, 4 dB(A) was additionally reduced.

System development to reduce floor impact sound in apartment houses

The floating floors used to reduce floor impact sound in European countries are not as compatible with Korean style floors because every residential floor in Korea is heated up by the floor heating method. In this case, considering the floor heat radiation effect, the cement screen is constructed to be about 40 to 50 mm thick. So constructing the low-density damping materials, such as glasswool, under the cement screen over 20 mm definitely makes some cracks. To prevent this kind of floor crack and to improve the impact insulation performance, the floating floor system using a plastic pallet and rubber was developed. The developed plastic pallet is 30 cm wide ×60 cm deep ×4 cm high and is designed to array on a concrete slab; above this plastic pallet, a 2-cm thick thermal insulator is constructed. On this, the insulator heating coil is installed, and finally the 4-cm-thick cement screen is constructed over that. The test results of impact insulation performance for the developed system show good improvement, about 15 dBa between before and after installation of the system.