1. No category

Report 4668-1b
30.10.2010
Measurement report
Sylomer - field test
Report 4668-1b
30.10.2010
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Contest
1 Introduction ......................................................................................................................... 3
1.1 Customer ...................................................................................................................... 3
1.2 The site and purpose of the measurements.............................................................................. 3
2 Measurements ..................................................................................................................... 6
2.1 Attenuation of the noise levels ............................................................................................. 6
2.2 Attenuation on one third octave bands...................................................................................13
3 Conclusions .......................................................................................................................16
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1 Introduction
1.1 Customer
Christian Berner Oy / Getzner Werkstoffe
Tuomas Laitinen
PL 12
01740 VANTAA
1.2 The site and purpose of the measurements
The site is located in southern Finland and the shortest distance between the buildings
and the railway track is about 40 meters. Before starting the planning process of the
building, vibration measurements were carried out at the site. The estimated ground
borne noise level LA,S,max (maximum A-weighted sound pressure level during a train
passing measured using time constant slow) in the building was about 45-48 dB.
In order to attenuate ground borne noise levels induced by the railway traffic a isolator
system was designed and installed in the buildings. The requirements for isolator system
were derived from vibration measurement results by Helimaki Acoustics. The designing
of the system and the calculations for acoustical response of the system were carried
out together by Helimaki Acoustics, Christian Berner and Getzner Werkstoffe.
The field measurements of the Sylomer isolators were carried out at a construction site.
At the time of measurements the building was almost finished and the isolators had
reached approximately at least 90 % of the full loading. The purpose of the measurements was to investigate the real attenuation achieved in the field with the isolators.
The measured building had seven floors. The horizontal Sylomer layers were 18mm
thick and the vertical layers 6mm (figures 1…5).
Figure 1. Building is supported by the concrete piles.
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Figure 2. Below the horizontal Sylomer layer (blue) is an unisolated part of building
foundation and on top of the isolator is the isolated part of building foundation.
Figure 3. In different loading positions a different type of Sylomer was used. Different
Sylomer types have different colors.
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Figure 4. The maintenance space under the building.
Figure 5. The sides of an isolated part of foundation that would be left under the ground
level after finishing the building were covered with vertical layers of 6mm Sylomer that
was protected by an EPS layer.
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2 Measurements
Measurement of the vibration levels was done with measurement unit having eight synchronized channels. Six of the channels were equipped with accelerometers in order to
measure the vibration levels in three directions simultaneously at two points. The upper
measurement point was located at the isolated part of building foundation and the other
measurement point was located underneath the Sylomer at unisolated part of building
foundation. Vibration measurements were done from two different positions (annex 1 &
2 and figure 6). One of the channels was equipped with microphone in order to measure
the sound levels in the reference room. Reference room was located at the other side of
the building than the railroad. The aim was to minimize the effect of the airborne noise.
All measurements were done with the vibration excitation induced by the train passing.
Figure 6. Upper measurement point is on the isolated and the second measurement
point is on the unisolated part of building foundation. The horizontal Sylomer layer separating the building parts is underneath the vertical Sylomer layer. The blue line shows
the location of horizontal layer.
2.1 Attenuation of the noise levels
The measured horizontal groundborne noise levels at the unisolated part of foundation
were 10…14 dB lower than the vertical levels. In the earlier surveys that were done before the start of the building process, all directions were assumed to be critical. Especially low frequency (<12Hz) vibration levels in horizontal direction were considerable. The
reason for horizontal vibration levels being now considerably lower than in planning
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stage is assumed to be because of the different kind of transfer function for the vertical
and horizontal vibration between the ground and foundation. Because the vertical vibration level was considerably higher than the horizontal directions, it is quite safe to assume that the measured noise levels at the reference room were caused by the vertical
component of the vibration.
The measured attenuation values for the Sylomer isolators are shown in the table 1. Attenuation is defined using two different methods. In the first column the attenuation is
defined using the difference between the measured noise level at the reference room
and the calculated ground borne noise level measured from the unisolated part of the
building foundation. Calculation of the ground borne noise level from the measured vibration signal is done according to the recommendation given by VTT (Technical Research Centre of Finland). Calculation method uses reference velocity of 1 nm/s and is
based on calculation models published by Federal Transit Admisnistration of U.S.A.
(http://www.fta.dot.gov/documents/FTA_Noise_and_Vibration_Manual.pdf
and
http://www.fra.dot.gov/downloads/RRDev/final_nv.pdf). When a starting value for calculation is the measured velocity level from building foundation the calculation models
taken into account following parameters: resonance, A-weighting, conversion from
inch/s to m/s, safety margin, floor in which the analysis is made.
In the second column the attenuation is defined using the difference between the calculated ground borne noise level from the measured vibration signal of the isolated and
unisolated part of the foundation. The position numbers in the table correspond to isolator numbering in the isolator plan done in the planning stage.
Table 1. The measured average attenuations in different directions.
Position
Direction
Attenuation between Attenuation between
reference room and isolated and unisounisolated
founda- lated part of foundation [dB] 1)
tion [dB] 2)
vertical
17
10
Position 12 perpendicular to track
- 3)
74)
along the track
- 3)
-5)
vertical
12
6
Position 26 perpendicular to track
- 3)
64)
along the track
- 3)
-5)
1) compare to figures 7…10
2) compare to figures 11…14
3) Noise level in the reference room is caused by the vertical vibration component and therefore the attenuation in
horizontal directions is impossible to define using the measured noise levels.
4) Attenuation was not possible to define from some of the train passings because the measured vibration levels
from the isolated part of foundation were too close to background levels.
5) Attenuation was not possible to define because the measured vibration levels from the isolated part of foundation were equal to background levels.
Theoretically the comparison between the unisolated and isolated part of foundation
should give more accurate results about the achieved attenuation levels for the isolators. In this case the relatively high background vibration levels in the building made it
impossible to measure the real vibration levels induced by the trains. The background
vibration levels in the building were caused by the HWAC equipments. Therefore the attenuation defined using the measured noise level in reference room and calculated
ground borne noise level in unisolated part of foundation is more reliable. Because the
vertical vibration levels in unisolated foundation were dominant compared to horizontal
components, the attenuation was possible to define only in vertical direction.
A train passing measured in vertical direction from the unisolated foundation from posiTämän asiakirjan osittainen julkaiseminen tai kopiointi on sallittua vain Insinööritoimisto Heikki Helimäki Oy:n kirjallisella luvalla.
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tion 12 is shown in figure 7. Ground borne noise levels for the same passing are shown
in figure 8. Taking into account 2dB attenuation/floor assumed in the VTT recommendation, one can define difference between the maximum noise levels in the room and in
the vertical direction in unisolated foundation to be 18 dB. From the figure 8 one can also easily see that the vertical component is dominant.
The corresponding results from position 26 are shown in figures 9 and 10. The vertical
component is again dominant. Comparing the maximum noise level in the reference
room to the vertical ground borne noise level in unisolated part of foundation, difference
of 10 dB can be defined.
mm/s^2
30.0
20.0
10.0
0.0
-10.0
-20.0
-30.0
0.0
5.0
10.0
15.0
s
Figure 7. Linear acceleration signal of a train passing measured from position 12 in vertical direction (unisolated foundation).
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dB(A)
45.0
40.0
35.0
30.0
25.0
20.0
0.0
5.0
10.0
15.0
s
Figure 8. Ground borne noise levels of a train passing are shown in figure 7. From top to
bottom: unisolated foundation vertical direction, unisolated foundation along the track,
unisolated foundation perpendicular to track and measured noise level in reference
room.
mm/s^2
20.0
10.0
0.0
-10.0
-20.0
0.0
5.0
10.0
15.0
s
Figure 9. Linear acceleration signal of a train measured from position 26 in vertical direction (unisolated foundation).
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dB(A)
45.0
40.0
35.0
30.0
25.0
20.0
0.0
5.0
10.0
15.0
s
Figure 10. Ground borne noise levels of the train passing are shown in figure 9. From
top to bottom: unisolated foundation vertical direction, measured noise level in reference room, unisolated foundation along the track and unisolated foundation perpendicular to track.
In the figures 11..14 the attenuation as a function of time during a train passing are
shown. According to figure 12 one can see that in position 12 the maximum attenuation
in vertical direction is 12 dB and the average attenuation is 10 dB. For the position 26
the corresponding values are 7 dB and 6 dB during a train passing. The background vibration levels in the building disturbed the analysis of the attenuation values especially
on the higher frequency bands (see the next chapter). Therefore the attenuation could
be even higher than stated above.
In the figure 13 the corresponding attenuation values are shown when the calculation is
done in the direction perpendicular to track. According to figure 13 on can see that in
position 12 the maximum attenuation perpendicular to track is 9 dB and the average attenuation is 6 dB. For the position 26 the corresponding values are 8 dB and 6 dB during
a train passing. Attenuation was not possible to define from some of the train passings
because the measured vibration levels from the isolated part of foundation were too
close to background levels.
In the figure 14 the corresponding attenuation values are shown when the calculation is
done in the direction along the track. Attenuation was not possible to define because
the measured vibration levels from the isolated part of foundation were equal to background levels. As mentioned earlier the horizontal vibration levels in the unisolated part
of foundation were notably lower than the vertical vibration levels and therefore only
the vertical component was relevant.
The measured ground borne noise levels in the building fulfilled the requirements set in
the planning phase (LA,S,max 30). In the figure 15 measured A-weighted sound pressure
levels on one third octave bands during a train passing in the reference room are
shown.
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mm/s^2
50
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mm/s^2
20.0
18.0
40
16.0
14.0
30
12.0
10.0
20
8.0
6.0
10
4.0
2.0
0
0.0
-2.0
-10
-4.0
-6.0
-20
-8.0
-10.0
-30
-12.0
-14.0
-40
-16.0
-18.0
-50
0.0
5.0
10.0
15.0
-20.0
0.0
5.0
10.0
15.0
s
s
Figure 11. On the left a measured train passing from position 12 is shown and on the
right from the position 26.
dB(A)
15.0
dB(A)
15.0
10.0
10.0
5.0
5.0
0.0
0.0
0.0
5.0
10.0
15.0
0.0
5.0
10.0
s
15.0
s
Figure 12. Attenuation between the unisolated part of foundation and isolated part of
foundation in vertical direction during train passing. Results are derived from the signals
shown in figure 11.
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dB(A)
15.0
dB(A)
15.0
10.0
10.0
5.0
5.0
0.0
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0.0
0.0
5.0
10.0
15.0
0.0
5.0
10.0
s
15.0
s
Figure 13. Attenuation between the unisolated part of foundation and isolated part of
foundation measured perpendicular to track during train passing. Results are derived
from the signals shown in figure 11.
dB(A)
15.0
dB(A)
15.0
10.0
10.0
5.0
5.0
0.0
0.0
0.0
5.0
10.0
15.0
s
0.0
5.0
10.0
s
Figure 14. Attenuation between the unisolated part of foundation and isolated part of
foundation measured along the track during train passing. Attenuations are derived from
the signals shown in figure 11.
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Figure 15. Measured A-weighted sound pressure level in the reference room during a
train passing on one third octave bands.
2.2 Attenuation on one third octave bands
The attenuation on one third octave bands was defined by comparing the vibration levels between the unisolated and isolated part of building foundation. In figure 15 the calculated attenuation values in vertical direction are shown. The HWAC installations/equipments caused relatively high background vibration levels in the building and
therefore the attenuation values could not be defined on the frequencies over 80 Hz. If
the vibration levels caused by the HWAC-equipments effect on the results below 80 Hz,
the real attenuation values are higher than shown in figure 16.
In figures 17 and 18 the corresponding attenuation values are shown in horizontal directions. In the direction perpendicular to track attenuation values were possible to define
only up to 63 Hz. On higher frequencies vibration levels were not possible to separate
reliably from the background levels. In the direction along the track the values are unreliable through the frequency band.
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Figure 16. Attenuation values defined in vertical direction on one third octave bands between the unisolated and isolated part of building foundation. The HWAC installations/equipments caused the high background vibration levels in the building and therefore calculation of attenuation values on the frequencies above 80 Hz was not possible.
Figure 17. Attenuation values defined in the direction perpendicular to track on one third
octave bands between the unisolated and isolated part of building foundation. Above 63
Hz the measured vibration levels were so low that the calculation was not possible.
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Figure 18. Attenuation values defined along the track on one third octave bands between the unisolated and isolated part of building foundation. The measured vibration
levels in this direction were so low that the results are not reliable through the frequency band.
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3 Conclusions
The measured ground borne noise levels in reference room induced by trains fulfilled
the requirement set in the planning phase LA,S,max
30dB. Measured vibration levels
from the unisolated part of building foundation revealed that the vertical component
was dominant. In fact the horizontal vibration levels were so close to the background
levels that it caused problems when the attenuation values were defined in horizontal
directions. All the measurements were carried out using real train passings as an excitation signal. Therefore better and more reliable results especially on higher frequencies
and in horizontal direction might have been achieved, if the man-made excitation would
have been used. However from the noise level measurements of the train passings it
was possible to define that the noise levels in the building fulfilled the requirements set
in the planning phase.
Because the vertical component was clearly dominant, it was possible to define the attenuation value in vertical direction by comparing the measured noise level in reference
room and the calculated ground borne noise level in unisolated part of foundation. Using
this method an average attenuation of 17 dB was achieved in position 12 and 12 dB in
position 26. Variation in results from different positions is not due to different Sylomer
type in different positions. This is because the whole isolated structure forms an integrated system.
In this case the comparison between measured noise level in reference room and calculated groundborne noise level in unisolated part of building foundation correspond better to the achieved total attenuation with the isolators because the comparison between
unisolated and isolated part of foundation was interfered by the vibration caused by the
HWAC equipments inside the building.
According to the measurements achieved attenuation level with the isolation system fulfills the estimations and requirements defined in the planning stage. In order to achieve
better isolation a thicker layer of Sylomer should be used. Results reveal that it is possible to estimate the isolation efficiency with reasonable accuracy in the planning phase if
the vibration levels are measured in advance at the site and if the material properties
are well documented.
Rauma 30.10.2010
Timo Huhtala
M. Sc.
Helimaki Acoustics – Rauma
Lyseokatu 5A3
26100 Rauma, Finland
+358 20 7118 597
[email protected]
Heikki Helimäki
M. Sc.
Helimaki Acoustics - Helsinki
Temppelikatu 6B
00100 Helsinki, Finland
+358 20 7118 591
[email protected]
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INSINÖÖRITOIMISTO HEIKKI HELIMÄKI OY
Temppelikatu 6 B, 00100 Helsinki
Puh. 020-7118 590, fax 09-589 33861
S-posti [email protected]
4688-1b Sylomer - field test
Annex 1
Measurement points
30.10.2010
Vibration measurements were done from two different position: position 12 (Sylomer type I) and
position 26 (Sylomer type II). In both positions the upper vibration measurement point was located
at the isolated part of building foundation and the other measurement point was located underneath
the Sylomer at unisolated part of building foundation. In all measurement points the vibration was
measured in all three directions. Noise levels were measured in the reference room with microphone.
1
805
4 620
8 825
5 700
5 300
6
4
3
2
gk=263 kN/m
qk= 34 kN/m
7
gk=470 kN/m
qk=101 kN/m
1
8
5
13
12
11
10
2
15
14
gk=118 kN/m
qk= 8 k N/m
750
5 400
17
16
gk=320 kN/m
qk= 65 kN/m
900
3
400
4
28
27
26
25
400
700
2185
4 600
gk=93 k N/m
gk=247 kN/m
qk= 47 kN/m
34
33
gk=389 kN/m
qk= 92 kN/m
3 200
44
gk=371 kN/m
qk= 70 kN/m
6
39
37
36
35
49
48
45
46
gk=86 k N/m
qk=55 k N/m
47
2050
5 400
400
2050
900
7
900
1700
ASUINRAKENNUKSESTA
gk=146 kN/m
qk= 8 k N/m
gk=180 kN/m
qk= 69 kN/m
750
900
5
43
42
41
40
38
32
31
5 400
1600
3 200
1600
gk=166 kN/m
qk= 20 kN/m
30
29
3 200
52
51
50
500
54
750
3 810
400 500
3 810
53
gk=152 kN/m
qk= 75 kN/m
gk=496 kN/m
qk=114 kN/m
8
58
60
59
1700
1600
57
56
55
3 600
3 600
450
750
9
750
gk=152 kN/m
qk= 75 kN/m
65
64
300
66
63
62
61
68
67
69
5 510
750
5 510
70
74
72
10
1600
73
71
79
4 600
gk=166 kN/m
qk= 20 kN/m
78
4 600
77
76
75
gk=93 k N/m
gk=118 kN/m
qk= 8 k N/m
80
750
11
84
83
82
81
3 530
3 530
89
gk=33 9 kN/m
qk= 66 kN/m
90
12
86
85
88
87
300 500
500
24
23
750
4 600
1600
22
21
20
19
18
3 200
900
3 890
gk=93 k N/m
9
750
5 400
1700
2 200
3 890
gk=337 kN/m
qk= 56 kN/m
gk=247 kN/m
qk= 47 kN/m
gk=412 kN/m
qk= 68 kN/m
900
gk=383 kN/m
qk= 59 kN/m
1700
gk=34 5 kN/m
qk= 56 kN/m
900
gk=458 kN/m
qk=161 kN/m
300 500
800
4 090
INSINÖÖRITOIMISTO HEIKKI HELIMÄKI OY
Temppelikatu 6 B, 00100 Helsinki
Puh. 020-7118 590, fax 09-589 33861
S-posti [email protected]
4688-1b Sylomer - field test
Annex 2
Measurement points
30.10.2010
Measurement points marked in the building foundation plan. Position numbers correspond to isolator
numbering in the calculations done in the planning stage of the building.
800
1700
gk=376 kN/m
qk= 95 kN/m
700
1340
2189
900
1700
500
gk=258 kN/m
qk= 58 kN/m