report%28september004

Brobyggnad

KTH Brinellvgen 34, SE-100 44 Stockholm

Tel: 08-790 9084, Fax: 08-21 69 49

www.byv.kth.se/avd/bro

Monitoring of the New Svinesund Bridge

Presentation of some measured data including the lifting of the mid-section of the bridge deck on 25 July

Raid Karoumi & Gerard James

Monitoring of the New Svinesund Bridge KTH/Brobyggnad

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Contents

1 General information & some important events .................................................................. 3

2 Presentation of statistical results ........................................................................................ 4

2.1 Wind and outside air temperature data................................................................... 4 2.2 Strain in the arch .................................................................................................... 6 2.3 Temperature in concrete....................................................................................... 11

3 Presentation of raw data results........................................................................................ 13

3.1 Arch frequencies .................................................................................................. 13 4 Summary and conclusions................................................................................................ 18

Copyright Dept. of Civil and Architectural Engineering KTH Stockholm September 2004


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1 General information & some important events

As the amount of triggered raw data files have increased after erecting the deck of the main span, the trigger criteria for standard deviation for accelerations was increased on the 10th of September from 2 to 10 mm/s2.

25th -27th of July the main span was erected.

During the period June to August 2004, several long stops occurred of the SMHI:s windsensor most certainly due to main 230 V power problems at site. SMHI is informed and will try to solve the problem by installing a battery backup to their system.

Klaus at NGI has investigated the ADSL alternatives and promised to present them during September.

On the 4th of June NGI modified/reconnected the power supply on the Swedish side in Bilfingers 230V supply box for datasystem and SMHI windsensor.

Starting on the 20th of May, wind direction is evaluated correctly in NGI's system. Wind direction data from SMHI agree now with data on BridgeMon..

Starting on the 8th of April, wind direction is evaluated correctly in SMHI's system.

Equipment for power failure alarm have been installed in week 12 for the data systems both on N- and S-side in order to minimize repair time and data logging down-time.

More important details and dates can be found in the diary on the monitoring projects homepage http://www.byv.kth.se/svinesund/diary.htm


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2 Presentation of statistical results

2.1 Wind and outside air temperature data

Figure 2.1 Outside air temperature.

Figure 2.2 Wind direction - wind rose.


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Figure 2.3 Wind speed and direction from SMHI:s system.

0

1

2

3

4

5

6

7

8

9

10

11

12

Feb Mar Apr May Jun Jul Aug

284 WindH.Mean

Figure 2.4 Wind speed from NGI/KTH:s system.


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2.2 Strain in the arch

-400

-300

-200

-100

0

100

200

300

400

Apr2004

May Jun Jul Aug Sep

Channel 74 (StatData 010404-260804.bin)

48 VWS1-T.Mean 290 RSS1-T.Mean (-560.62)

291 VWS1-B.Mean (+100)

Figure 2.5 Comparison of strain readings at segment S1. The above figure show clearly that the two strain signals from vibrating-wire and resistance strain sensors agree well with each other. VWS1-T show signal disturbance in August.


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-250

-200

-150

-100

-50

0

50

100

150

200

250

300

350

Oct2003

Jan 2004 Apr Jul

Channel 74

48 VWS1-T.Mean 292 VWN1-T.Mean (-25)

Figure 2.6 Comparison of strain readings from the top of segment S1 and N1.

This figure show that the top of N1 is in compression compared to S1. The two curves follow each other rather closely until the release of the back-stay cables in March. Possible reasons for the different behaviour of S1 and N1:

different tension in the back-stay cables on the S- and N-side the erection of side span deck sections started earlier on the Norwegian side different support stiffness


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-450

-400

-350

-300

-250

-200

-150

-100

-50

0

50

100

Oct2003

Jan 2004 Apr Jul

Channel 74

293 VWS1-B.Mean (+100) 294 VWN1-B.Mean (+155)

Figure 2.7 Comparison of strains at the bottom of segments N1 and S1. Signal disturbance in VWN1-B.


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-400

-300

-200

-100

0

100

200

300

400

Oct2003

Jan 2004 Apr Jul

Channel 74

48 VWS1-T.Mean 290 VWS6-T.Mean (+140)

293 VWS1-B.Mean (+100) 298 VWS6-B.Mean (+190)

Figure 2.8 Comparison of strains at S1 and S6. At the final stag, approximately zero tension at VWS6-T and VWS1-T is obtained closing the earlier developed cracks.


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-1500

-1000

-500

0

500

1000

Mar2004

Apr May Jun Jul Aug

Channel 74

295 RSS25-B.Mean (-1940) 296 RSS25-T.Mean (-2100)

297 RSS25-W.Mean (+980)

Figure 2.9 Strain readings from RSS25-T, RSS25-B and RSS25-W. As seen from the strain curves, the lifting of the main deck started on the 25th of July. The reinforcement at the top of segment S25 has approximately zero strain at this final stage. Developed cracks on the top of the segment are now closed. The east and west walls of segment S25 are still in tension, possibly due to the two installed steel pressure bars.


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2.3 Temperature in concrete

15

20

25

30

35

40

45

50

100

200

300

400

500

600

700

800

900

1000

Thu 1Jul 2004

Thu 8 Thu 15 Thu 22 Sun 1 Sun 8 Sun 15 Sun 22Channel 74

176 TS25-WO.Mean 184 TS25-WM.Mean

297 RSS25-W.Mean (+980)

25

30

35

40

45

50

400

500

600

700

800

900

Mon 9Aug 2004

Tue 10 Wed 11 Thu 12 Fri 13Channel 74

20

25

30

35

40

45

300

400

500

600

700

800

900

Sat 7Aug 2004

3:00 6:00 9:00 12:00 15:00 18:00 21:00 Sun 8Channel 74

( )

Figure 2.10 This figure illustrates the temperature effect on the strain in section S25. The right Y-axis gives the strain (microstrain) and the left Y-axis the temperature (degrees


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Celsius). As seen a temperature difference of about 9 degrees corresponds to a strain difference of about 260 microstrain.

-10

-5

0

5

10

15

20

25

30

Jan 2004 Feb Mar Apr May Jun Jul Aug Sep

Channel 74

84 TS6-B.Mean 88 TS6-E.Mean 92 TS6-W.Mean 96 TS6-T.Mean

Figure 2.11 This figure illustrates the temperature difference between top, bottom, east and west walls of segment S6.


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3 Presentation of raw data results

3.1 Arch frequencies

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

500

1000

1500PS

D v

ert

Power Spectrum ACCS14(D20040709141040.bin)

1.17

0.77

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

1000

2000

3000

4000

PSD

hor

is

Frequency/Hz

0.43

0.87

1.37

Figure 3.1 The power spectral density from the accelerometers at approximately the quarter point of the arch, S14. The measurements were made on the 9th July 2004.

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

500

1000

1500

PSD

ver

t

Power Spectrum ACCN26(D20040709141040.bin)

1.17

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

0.5

1

1.5

2

x 104

PSD

hor

is

Frequency/Hz

0.43

Figure 3.2 The power spectral density from the accelerometers at the mid-point of the arch, N26. The measurements were made on the 9th July 2004.


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0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

10

20

30

40

PSD

ver

t


0.76

1.16

1.72

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

50

100

PSD

hor

is

Frequency/Hz

1.37

0.85

0.43

Figure 3.3 The power spectral density from the accelerometers at approximately the quarter point of the arch, S14. The measurements were made on the 21st July 2004.

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

100

200

300

PSD

ver

t


1.16

1.72

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

10

20

30

40

50

PSD

hor

is

Frequency/Hz

0.42

1.32 1.37

Figure 3.4 The power spectral density from the accelerometers at the mid-point of the arch, N26. The measurements were made on the 21st July 2004.


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0 0.5 1 1.5 2 2.5 3 3.5 40

2000

4000

6000

PSD

ver

t


0.75

1.5

2.47

0 0.5 1 1.5 2 2.5 3 3.5 40

1000

2000

3000

4000

PSD

hor

is

Frequency/Hz

0.99

0.46

Figure 3.5 The power spectral density from the accelerometers at approximately the quarter point of the arch, S14. The measurements were made on the 25th Aug 2004.

0 0.5 1 1.5 2 2.5 3 3.5 40

500

1000

1500

2000

2500

PSD

ver

t


2.471.5

0 0.5 1 1.5 2 2.5 3 3.5 40

0.5

1

1.5

2

x 104

PSD

hor

is

Frequency/Hz

0.46

1.05

Figure 3.6 The power spectral density from the accelerometers at the mid-point of the arch, N26. The measurements were made on the 25th Aug 2004.


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0 0.5 1 1.5 2 2.5 3 3.5 40

0.05

0.1

0.15

PSD

ver

t


1.50

2.35

3.42

0 0.5 1 1.5 2 2.5 3 3.5 40

0.05

0.1

0.15

PSD

hor

is

Frequency/Hz

0.43

0.94

1.40

Figure 3.7 The power spectral density from the accelerometers at approximately the quarter point of the arch, S14. The measurements were made on the 4th Sept 2004.

0 0.5 1 1.5 2 2.5 3 3.5 40

0.05

0.1

0.15

0.2

0.25

PSD

ver

t


1.49

0 0.5 1 1.5 2 2.5 3 3.5 40

0.1

0.2

0.3

0.4

PSD

hor

is

Frequency/Hz

0.43

1.04

Figure 3.8 The power spectral density from the accelerometers at the mid-point of the arch, N26. The measurements were made on the 4th Sept 2004.


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Table 3.1. A comparison of the measured natural bending frequencies during the construction phase. The 6th of February was before the arch stone was in place. On the 9th and the 21st of July the middle section of the bridge deck was not in place. On the 25th of August and for the September measurements, the bridge deck was complete.

Horizontal Frequency Hz Vertical Frequency Hz Date 1st 2nd 3rd 1st 2nd 3rd 6th Feb 2004 0.34 1.25 0.47 0.98

9th July 2004 0.43 0.87 1.37 0.77 1.17 -

21st July 2004 0.42 0.85 1.37 0.76 1.16 1.72

25th Aug 2004 0.46 1.00 - 0.75 1.5 2.47

4th Sept 2004 0.43 0.94-1.04 1.40 (0.77) 1.49

6th Sept 2004 0.44 0.95 (0.77) 1.49 2.35-2.41 Table 3.1 shows the natural frequencies of the arch during different stages of the construction phase. For the measurement on the 6th of February, the arch stone was not in place and therefore the measurement was for the two halves for the arch acting separately. The mid-section of the bridge deck was lifted into place between the 25th to the 27th of July 2004. At the time of writing this report we lack information regarding the construction methods at different stages such as the manner in which the bridge deck is attached to the arch during these dates and when the mid-section of the bridge deck had been welded to the earlier constructed bridge deck.


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4 Summary and conclusions

This short report presents some measured data including the lifting of the mid-section of the bridge deck on the 25-27 of July. The presented figures show very interesting results, especially those for temperature and concrete strain. Earlier developed cracks at the top wall of the arch are now closed as this part of the arch have no tension at this final stage. The east and west walls of segment S25 are still in tension, possibly due to the two installed steel pressure bars. The strain curves for the part of the Swedish arch do not agree with those of the Norwegian part. This illustrates the influence of the order in which the work on site is done, as it is believed that the construction sequence of the side span decking sections have affected the strains in the arch. Valuable wind data has been lost during the summer period due to main power failures. It was interesting to note that the first horizontal and vertical natural frequencies of the arch do not appear to have changed appreciably after the lifting of the mid-section of the steel bridge deck. Compare a change in the first natural frequencies of 0.42 to 0.46 Hz for the horizontal and unchanged at approximately 0.75 Hz for the first vertical. However, the higher natural frequencies have increased notably.

A great deal of additional information and reports on The New Svinesund Bridge are available on theWorld Wide Web at the following address: www.byv.kth.se/svinesund

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