PROCEEDINGS of the23rd International Congress on Acoustics
9 to 13 September 2019 in Aachen, Germany

Continuing Prediction of Heavy/Hard Impacts on Resilient SportsFloors in Existing Buildings
Matthew GOLDEN1; Faiz MUSAFERE2
1,2Pliteq, Inc, Canada

ABSTRACTPreviously we have presented a method to predict the acceleration from heavy/hard impacts in existingbuildings to replace more traditional methods. The traditional methods for the assessment of noise andvibration due to heavy/hard impacts in an existing building can be cumbersome and time consuming, have
low repeatability, and does not allow for evaluation of additional solutions not present at the time of testing.
The new method consists of measuring on-site vibrational transfer functions, measuring a force pulse that agiven weight will exert onto a resilient floor and then combining those elements to predict the vibration. Thismethod can predict the acceleration or vibration in a building due to any arbitrary combination of impact
source and resilient flooring. The new measurements obtained for this paper were conducted in a true field
application in both narrow and one-third octave bands. The predictions obtained are compared to on-siteweight drop measurements in order to qualify the predictive model.
Keywords: Vibration, Impact, Prediction

1. INTRODUCTION
The issue of heavy/hard impacts in buildings has been an issue for a number of years1,2,3,4,5,8 .
Currently, the assessment of the noise and vibration due to heavy/hard impacts in an existing building
can be quite cumbersome. All of the potential floor coverings and the heavy/hard source need to be
shipped to the site. Often impact sources are not sent to the site whatever type of mass happens to bepresent at the site is used to generate the heavy/hard impacts. Therefor there is often little
reproducibility between measurements.
Overall, this testing regimen is quite arduous, time consuming, and not very repeatable. In
recent years, the authors have built a drop tower to repeatedly test fitness flooring performance in acontrolled environment4,5 and presented a method to combine the results from the drop tower withon-site measured transfer functions to predict the vibration in buildings 8 .
This paper shows that the method works in real field conditions. The method was previously
shown to use a narrow band analysis, but it has now been shown to work as a one-third octave bandanalysis similar to what others6 have suggested. That analysis used a method similar to the Delta IIC in
ASTM E21797 but presented method using one-third octave band “transfer functions”. Previously,
only locally reacting fitness flooring was used. This paper shows that the method has some success forhybrid systems that combine locally reacting fitness floors with light weight floating floors.

2. Experimental Setup
2.1 Samples Tested
For this experiment, a total of five different fitness flooring systems were used that consisted of twodifferent manufactures fitness flooring tiles, alone and in combination with the same light-weightfloating floor systems. The combination fitness tiles and light-weight floating floors are referred to as
hybrid solution. All solutions are summarized in Table 1.

12mgolden@pliteq.com
fmusafere@pliteq.com

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Table 1 – Summary of test specimens used in experiment.
ID

Product name

Material/specimenthickness

1GenieMat® FIT7070 mm (2 ¾”)•

Recycled rebounded crumb rubber tile

2ApolloTM

38 mm (1 ½”)•

Recycled rebounded crumb rubber tile••

Recycled rebounded crumb rubber tile
Patented recycled rebounded crumb rubber
sheet with bilateral sinusoidal surface
Double plywood floating floor tile with low
dynamic modulus isolators.

GenieMat® FIT70
3GenieMat® FF25
GenieMat® FF70LDM

165 mm (6 ½”)•••

ApolloTM
4GenieMat® FF25
GenieMat® FF70LDM

133 mm (5 ¼”)

GenieMat® FIT70
GenieMat® FF70LDM

140 mm (5 ½”)

5Material/specimen type•••

Recycled rebounded crumb rubber tile
Patented recycled rebounded crumb rubber
sheet with bilateral sinusoidal surface
Double plywood floating floor tile with low
dynamic modulus isolators.
Recycled rebounded crumb rubber tile
Double plywood floating floor tile with low
dynamic modulus isolators.

2.2

Force Pulse
The force pulse was measured on the five different fitness flooring solutions with Pliteq’s
proprietary drop tower shown in Figure 1. Two carriages are supported on low friction rails as to only
allow one axis of motion. The upper carriage lifts the lower carriage to a selected height and releasesit so that the lower carriage will impact the test specimen with close to free-fall like conditions. The
lower carriage can be fitted with various load plates to adjust the mass of the lower carriage and impact
foot shape can be changed to simulate different types of weight impacts. A load cell measures theimpact force pulse. Narrow and one-third octave band analyses were conducted on the time signals.
For this experiment, the drop height was set to 0.5 m (19.7 in) and the mass was 22.7 kg (50 lbs).

Upper CarriageLower Carriage
Force GaugeImpact FootTest Specimen

Figure 1 – Heavy/Hard Impact Drop Tower at Rest.
2.3 Field Measurements
The same type of fitness flooring tiles were installed on the 8th floor of the field location in Toronto,
ON. A machined, semi-spherical mass was lifted to the same initial height above the fitness floor as it
was when tested with the drop tower. It was released from rest and allowed to impact once before it
was caught. (Figure 2)

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Three accelerometers were placed on the same concrete slab as the fitness tiles as shown in Figure 3.
The vibration at each accelerometer was measured due to drops on each of the different fitness flooring
solutions.
Accel. Loc. 2
Drop Location

0.82 m3.12 m
Accel. Loc. 1

6.85 m

Accel. Loc. 3

Figure 2 – Field testing of fitness tiles withmachined heavy/hard source

Figure 3 – Plan view of field-testing locations.

2.4

Transfer Function Measurement
An impact sledge hammer was used to impact the same locations as the heavy/hard impacts on
the concrete slab. The force impulse and the resulting accelerations were measured, and narrow and
one-third octave band analyses were conducted on the signals. The impact hammer input force andresulting vibration were used to calculate a transfer function in narrow band and one-third octave
bands. These transfer functions were combined with the force pulses obtained from the drop tower toderive an estimated acceleration that can be compared to the actual measured vibration.

3. RESULTS AND ANALYSIS
3.1

Force Pulse Measurements
First, the force pulse on the five types of fitness flooring were measured with the heavy/hard
impact drop tower, described above, with a lower carriage mass approximately equal to the machined
heavy/hard source used in the field testing. Figure 4 shows the performance of three of the five

Figure 4 - Time and frequency response of the force pulse on three of the five fitness floors.

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flooring solutions. Since the other two hybrid solution force pulses are very similar to hybrid
solution force pulse shown they are left out of the analysis due to the limited scope of the paper. Thelower the maximum force and longer the pulse width the better the fitness flooring does indecreasing noise and vibration. The frequency response of the fitness flooring solutions also changes
such that the 3dB cutoff frequency of the apparent low pass filter decreases for solution with wider
force pulse widths.
3.2 Field Measurement of Heavy/Hard Impacts
Figure 5 shows the data collected at location 3 for several consecutive impacts for three of thefloor coverings. The figure shows the time history, narrow band and one-third octave band analysis
for each floor covering. The data collected for the locally reacting tiles is very repeatable. Whilethe data collected for the hybrid system shows slightly less repeatability. As expected, the amplitudedecreased significantly as the impacts were on successively higher performing fitness flooring. Thepeak amplitude of the vibration response at location 3 on the GenieMat® FIT70, Apollo, and theGenieMat® FIT70 on GenieMat® FF70LDM was approximately 0.02 m/s 2 , 0.07 m/s2 , and 0.013 m/s2
respectively. This is approximately in proportion to the relative levels for maximum force measured
on the drop tower. Both the narrow band and one-third octave analysis show the peak of acceleration
occurred in the 10 to 200 Hz range.

Figure 5 – Vibration response in time, (top row) narrow band (middle row) and one-third octave bands(bottom row) at location 3 due to heavy/hard impacts on GenieMat® FIT70 (left column), Apollo 38 mm(center column), and GenieMat® FIT70 on GenieMat® FF70LDM (right column).

3.3

Measurement of Transfer Function
The transfer functions were measured using an impact sledge hammer and several
accelerometers. The sensors are listed in Table 2. The signal from the impact sledge hammer wasused as the input signal to calculate the transfer function. The signals from the accelerometers wereused as the output. The coherence of several impacts, along with the narrow and one-third octave
band transfer function magnitude are shown in Figure 6.

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Table 2 – Summary of sensors used.
Sensor Type

Sensor Make and Mode

Sensitivity

Impact Hammer

PCB065D50

0.23 mV/N (1 mV/lbf)

Accelerometer 1

PCB 353B03

10 mV/g

Accelerometer 2

Dytran 3055D2

100 mV/g

Accelerometer 3

PCB 393B05

10 V/gFigure 6 – Coherence, narrow and one-third octave band transfer functions for location 3.

Figure 7 – Predicted results on top of measured data in time, (top row) narrow band (middle row) andone-third octave bands (bottom row) at location 3 due to heavy/hard impacts on GenieMat® FIT70 (leftcolumn), Apollo 38 mm (center column), and GenieMat® FIT70 on GenieMat® FF70LDM (right column).

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3.4 Prediction of vibration due to heavy/Hard Impacts
The transfer functions were then combined with the force pulse data to calculate an estimatedtime history, narrow and one-third octave band vibration levels for each floor covering. Theprediction results and measured values at location 3 for each flooring solutions discussed above areshown in Figure 7. In the frequency range when coherence is high (10 to 200 Hz) very good
agreement is shown for the locally reacting flooring solutions. The predictions results for the hybrid
flooring solutions are not quite as good but still show general agreement with measured values. The
results can also be numerically converted into velocity as is more commonly used in building
vibration. (Figure 8)
Below 10 Hz and above 200 Hz, the results do not match well. If techniques are developed toincrease the coherence of the field measured transfer functions, the agreement between predicted andmeasured results would likely increase.

Figure 8 – Velocity prediction results in narrow band (middle row) and one-third octave bands (bottom row)
at location 3 due to heavy/hard impacts on GenieMat® FIT70 (left column), Apollo 38 mm (center column),and GenieMat® FIT70 on GenieMat® FF70LDM (right column).

4. CONCLUSIONAs previously shown, the force pulse of a heavy/hard impact source on fitness flooring can bemeasured in a controlled laboratory environment. A transfer function between the impact force at one
location and the acceleration at a several other locations can be measured. This transfer function canthen be combined with the laboratory measured force pulse to obtain an estimated time andfrequency response. The analysis can be conducted in narrow or one-third octave bands. This
calculated estimate shows good agreement with the in situ measured time and frequency response
due to a heavy/hard impacts in the range of 10 to 200 Hz. Further work is needed to improve themethodology to include a greater frequency range. Addition work should be performed to test themethodology over larger distances and building types, and to extend the predictions to sound.
ACKNOWLEDGEMENTS
The authors would like to thank the many of the engineers at Pliteq who have assisted with fieldmeasurements, drop tower testing, and maintenance, and equipment design including but not limited toWil Byrick, Paul Gartenburg, Colin Bradley, Alex White and Mark Carli. We would also like to thankPliteq management for allowing us to take time to conduct this research and build the neededequipment.
REFERENCES
1. Paul Gartenburg and Paul Downey, “Comparing various fitness flooring assemblies using heavy/softand heavy/hard impact”, Internoise 2015, San Francisco, CA, US.
2. Paul Gartenburg and Tony Nash, “Fitness Noise Control Products – Should we be Measuring System
or Material Properties?”, NoiseCon 2016, Providence, RI, US.

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3. Matthew V. Golden and Paul Gartenburg, “The effectiveness of resilient sports flooring on noise fromcrossfit activities”, The Journal of the Acoustical Society of America 139, 2038 (2016); Presentation
4. Paul Gartenburg and Matt Golden, “Comparing force impulses for various fitness flooring assemblies”,
NoiseCon 2017, Grand Rapids, MI US.
5. Matthew V. Golden, “ Drop Tower Testing—The next step in heavy weight impact testing”, The
Journal of the Acoustical Society of America 143, 1726 (2018); Presentation
6. John LoVerde, Rich H. Silva, Wayland Dong and Samantha Rawlings, “Investigation into aStandardized Test Method for Measuring and Predicting Heavy Weight Impact Noise Transmission”.
Internoise 2015, San Francisco, CA, US.
7. ASTM E2179-03, Standard Test Method for Laboratory Measurement of the Effectiveness of Floor
Coverings in Reducing Impact Sound Transmission Through Concrete Floors, ASTM International,West Conshohocken, PA, 2016, www.astm.org
8. Matthew V. Golden and Paul Gartenburg, “Prediction of Heavy Weight Drops on Resilient Sports
Floors in Existing Buildings”, Internoise 2018, Chicago, IL, US.

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