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Roctest /SMARTEC Webinar Series June 06, 2012. Lessons learned: ten-year structural health monitoring of high-rise buildings. Branko Glišić 1 , Daniele Inaudi 2 , Joo Ming Lau 3 , and Chor Cheong Fong 3 1 Princeton University, USA (speaker) 2 SMARTEC SA, Switzerland - PowerPoint PPT Presentation
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©SHM Lab, SMARTEC, HDB
Lessons learned: ten-year structural health monitoring of high-rise
buildings
Branko Glišić1, Daniele Inaudi2, Joo Ming Lau3, and Chor Cheong Fong3
1Princeton University, USA (speaker)2SMARTEC SA, Switzerland3Housing Development Board, Singapore
Roctest/SMARTEC Webinar SeriesJune 06, 2012
©SHM Lab, SMARTEC, HDB 2/29Ten-year SHM of high-rise buildings
• Introduction
• Monitoring criteria
• Monitoring method
• Assessment at local (column) level
• Assessment at global (building) level
• Comparison between buildings
• Conclusions
Outline
©SHM Lab, SMARTEC, HDB 3/29Ten-year SHM of high-rise buildings
Punggol project – introduction • Collaborative study between HDB – Singapore’s
Public Housing Authority & Smartec, Switzerland• Purpose of study
– As a part of quality assurance, preventive maintenance– Understanding of structural behavior
• Long-term lifespan structural monitoring • Fiber optic sensing monitoring system used
based on low coherence interferometry• ~400 buildings equipped with sensors• 10+ years long-term monitoring: monitoring
during construction, 48-hours continuous sessions, post-tremor evaluation
©SHM Lab, SMARTEC, HDB 4/29Ten-year SHM of high-rise buildings
• Critical structural members to be monitored
• Local (column) and global (building) structural monitoring required
• Long-term lifespan monitoring incl. construction
• Structural (not material) monitoring required
• Costs for monitoring to be affordable
Monitoring criteria
©SHM Lab, SMARTEC, HDB 5/29Ten-year SHM of high-rise buildings
• Critical structural members selected based on numerical modeling• Structural monitoring long-gage sensors• Long-term monitoring incl. construction embeddable fiber optic
sensors• Affordable costs
– Only 10 columns monitored– No temperature monitoring (yearly variation in Singapore:
27C5C)– Periodic manual measurements – Yearly 48-hour sessions (include ambient temperature and relative
humidity monitoring)
Monitoring method
©SHM Lab, SMARTEC, HDB 6/29Ten-year SHM of high-rise buildings
• No bending in columns single sensor per column
• Data analyzed at both local (column) level and global (building) level
• Several neighboring buildings built by same contractor, with same design and concrete quality, and instrumented with similar monitoring system possible comparison between buildings
Monitoring method, continued
1st (ground) floor
2nd floor
Foundations
Co
lum
n
Sen
sor
©SHM Lab, SMARTEC, HDB 7/29Ten-year SHM of high-rise buildings
Sensors positions
C10
C3
C4
C5C6
C7
C8
C2
C1
C9
1ST STOREY FLOOR PLAN
MULTI - STOREY VOID
UNIT A
UNIT B
UN
IT C
UNIT D
UNIT EUNIT F
©SHM Lab, SMARTEC, HDB 8/29Ten-year SHM of high-rise buildings
Construction stage
• Six blocks founded on piles• 19 storeys tall, 6 units per storey• Columns are cast in-situ
©SHM Lab, SMARTEC, HDB 9/29Ten-year SHM of high-rise buildings
Embedding on-site
SOFO sensor
Passive zone
Junction box
Embedding in plant
After pouring Measurement
Photos of installation
©SHM Lab, SMARTEC, HDB 10/29Ten-year SHM of high-rise buildings
Completed building
©SHM Lab, SMARTEC, HDB 11/29Ten-year SHM of high-rise buildings
Results – 10 years record
48-h
‘04
Trem
or
End of construction
48-h
‘05
48-h
‘06
48-h ‘07 Temperature
©SHM Lab, SMARTEC, HDB 12/29Ten-year SHM of high-rise buildings
• Sensors measure axial deformation in columns• Determine measured strain in columns• Evaluate whether strains is acceptable by
– Comparison between measured strain and estimated theoretical (design) values
– Comparison between measured strain and ultimate strain
• Use 48-hours campaigns in order to:– Learn the building behaviour caused by daily temperature
changes and inhabitant fluctuations– Record the health state of the building as a reference for
comparison with the future monitoring results
Assessment at local level
©SHM Lab, SMARTEC, HDB 13/29Ten-year SHM of high-rise buildings
Average strain measured by sensor (simplified):
m(t) = s(t) +(t) +T(t) + sh(t)
T = thermal strain
sh = total shrinkage
= creep
s = elastic strain (due to load)
Neglected (temperature not measured)
Estimated, simplified CEB-FIP MC90
Estimated (using s), simplified CEB-FIP
MC90 Design values
Estimation of total strain in columns
©SHM Lab, SMARTEC, HDB 14/29Ten-year SHM of high-rise buildings
Measured vs. designStrain components, column C9
-700
-600
-500
-400
-300
-200
-100
0
24.05.01 24.05.02 24.05.03 23.05.04 23.05.05
Time
Av
era
ge
str
ain
[m ]
Measured (total)
Shrinkage (CEB-FIP)
Creep (CEB-FIP)
Load (design)
Total (design)
Strain components, column C3
-700
-600
-500
-400
-300
-200
-100
0
24.05.01 24.05.02 24.05.03 23.05.04 23.05.05
Time
Ave
rag
e st
rain
[m ]
Measured (total)
Shrinkage (CEB-FIP)
Creep (CEB-FIP)
Load (design)
Total (design)
End of constr. of 19 storeys End of constr. of 19 storeys
©SHM Lab, SMARTEC, HDB 15/29Ten-year SHM of high-rise buildings
48 hours, total av. strain, C6 (1683)
-594
-592
-590
-588
-586
-584
-582
-580
-578
-576
-574
-572
01.07.0412:00
01.07.0420:00
02.07.0404:00
02.07.0412:00
02.07.0420:00
03.07.0404:00
03.07.0412:00
Time [date & hour]
Ave
rag
e st
rain
[m ]
20
21
22
23
24
25
26
27
28
29
30
31
Am
b. t
emp
erat
ure
[°C
]
C6 (1683)
Amb. temp.
48-hrs 2004: strain & amb. temp.
©SHM Lab, SMARTEC, HDB 16/29Ten-year SHM of high-rise buildings
48 hours, total av. strain, C4 (1669)
-652-650-648-646-644-642-640-638-636-634-632-630-628-626-624-622-620-618-616-614-612-610-608-606-604-602
10:0
0
12:0
0
14:0
0
16:0
0
18:0
0
20:0
0
22:0
0
00:0
0
02:0
0
04:0
0
06:0
0
08:0
0
10:0
0
12:0
0
14:0
0
16:0
0
18:0
0
20:0
0
22:0
0
00:0
0
02:0
0
04:0
0
06:0
0
08:0
0
10:0
0
12:0
0
14:0
0
Time [hour]
Ave
rag
e st
rain
[m ] C4 (1669) 2004 C4 (1669) 2005
C4 (1669) 2006 C4 (1669) 2007
48-hour example
©SHM Lab, SMARTEC, HDB 17/29Ten-year SHM of high-rise buildings
48 hours, total av. strain, C6 (1683)
-602-600-598-596-594-592-590-588-586-584-582-580-578-576-574-572-570-568
10:0
0
12:0
0
14:0
0
16:0
0
18:0
0
20:0
0
22:0
0
00:0
0
02:0
0
04:0
0
06:0
0
08:0
0
10:0
0
12:0
0
14:0
0
16:0
0
18:0
0
20:0
0
22:0
0
00:0
0
02:0
0
04:0
0
06:0
0
08:0
0
10:0
0
12:0
0
14:0
0
Time [date & hour]
Ave
rag
e st
rain
[m ]
C6 (1683) 2004 C6 (1683) 2005
C6 (1683) 2006 C6 (1683) 2007
48-hours example (continued)
©SHM Lab, SMARTEC, HDB 18/29Ten-year SHM of high-rise buildings
48 hours averaged ambient temperature '04,'05, '06 and '07
24
25
26
27
28
29
30
31
Ave
rag
ed A
mb
. T
emp
erat
ure
[°C
]Averaged 2004 Averaged 2005
Averaged 2006 Averaged 2007
48 hours averaged relative humidity '04, '05, '06 and '07
60%
65%
70%
75%
80%
85%
Rel
ativ
e H
um
idit
y [%
]
Averaged 2004 Averaged 2005
Averaged 2006 Averaged 2007
48-hrs 2004-2007: RH & amb. temp.
©SHM Lab, SMARTEC, HDB 19/29Ten-year SHM of high-rise buildings
48 hours averaged strain 2004, 2005, 2006 and 2007
-800
-780-760
-740
-720-700
-680
-660-640
-620-600
-580
-560-540
-520
-500-480
-460
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10
Ave
rag
ed s
trai
n [
m ]
Averaged 2004
Averaged 2005
Averaged 2006
Averaged 2007
24-hrs 2004 - 2007
©SHM Lab, SMARTEC, HDB 20/29Ten-year SHM of high-rise buildings
Punggol EC26, post-tremor evaluation
-800
-750
-700
-650
-600
-550
-500
-450
12.06.04 11.09.04 11.12.04 12.03.05 12.06.05
Time [date & hour]
Avera
ge s
train
[m ]
C1 (1675)
C2 (1668)
C3 (1676)
C4 (1669)
C5 (1663)
C6 (1683)
C7 (1670)
C8 (1682)
C9 (1662)
C10 (1677)
48-hours 2004 Before and after tremor
48-hours 2005
Post-tremor Analysis
©SHM Lab, SMARTEC, HDB 21/29Ten-year SHM of high-rise buildings
• Comparison of strain development of columns per units A, B, C and E
• Comparison of differential deformation of columns• Statistical analysis
Assessment at Global Level
Settlement
After settlementBefore settlement
Sh
ort
enin
g
Elo
ng
atio
n
Sh
ort
enin
g
©SHM Lab, SMARTEC, HDB 22/29Ten-year SHM of high-rise buildings
-700-650-600-550-500-450-400-350-300-250-200-150-100-50
0
19/05/01 16/09/01 14/01/02 14/05/02 11/09/02 09/01/03 09/05/03
Age [Date+Time]
Ave
rag
e st
rain
[]
Col. 1
Col. 2
Col. 3
Col. 4
Col. 5
Col. 6
Col. 7
Col. 8
Col. 9
Col. 10
19th 17th 15th 13th 11th 9th 7th 5th 18th 16th 14th 12th 10th 8th 6th 4th 2nd
Construction of storeys Other construction works
Development of strain for C9 unusual, column under loaded
During Construction
©SHM Lab, SMARTEC, HDB 23/29Ten-year SHM of high-rise buildings
Unit B - correlation with C4
-800
-700
-600
-500
-400
-300
-200
-100
0
-700 -600 -500 -400 -300 -200 -100 0
Measurement of column C2 [m]
Mea
sure
men
ts o
f co
lum
ns
C1
and
C3
[m ]
C5 (1663)
C6 (1683)
C4
C5
C6
Linear Correlation in long-term
©SHM Lab, SMARTEC, HDB 24/29Ten-year SHM of high-rise buildings
Linear Correlation in long-termUnit A - correlation with C2
-800
-700
-600
-500
-400
-300
-200
-100
0
-700 -600 -500 -400 -300 -200 -100 0
Measurement of column C2 [m ]
Mea
sure
men
ts o
f co
lum
ns
C1
and
C3
[m ]
C3 (1676)
C1 (1675)
Event
©SHM Lab, SMARTEC, HDB 25/29Ten-year SHM of high-rise buildings
Settlement in unit A
h
L1 L2
A1 A2 A3
v1 v2 v3
h
L1 L2
A1 A2 A3
v
C3 – smaller than expected C1 – bigger than expected
Settlement of column C3 evaluated to ~ 0.25 to 1 mm
C9 – over dimensioned
©SHM Lab, SMARTEC, HDB 26/29Ten-year SHM of high-rise buildings
Punggol EC26 Blk166B - June 01 - March 05
-800
-700
-600
-500
-400
-300
-200
-100
0
09/06/20010:00
27/01/20020:00
16/09/20020:00
06/05/20030:00
24/12/20030:00
12/08/20040:00
01/04/20050:00
Time
Ave
rag
e st
rain
[]
S1671 S1681
S1680 S1678
S1679 S1673
S1674 S1666
S1667 S1664
-800
-700
-600
-500
-400
-300
-200
-100
0
09/06/20010:00
27/01/20020:00
16/09/20020:00
06/05/20030:00
24/12/20030:00
12/08/20040:00
01/04/20050:00
Two Punggol EC26 BlksPunggol EC26, May 2001-April 2005
-800
-700
-600
-500
-400
-300
-200
-100
0
24/05/2001 0:00
22/11/2001 12:00
24/05/2002 0:00
22/11/2002 12:00
24/05/2003 0:00
22/11/2003 12:00
23/05/2004 0:00
21/11/2004 12:00
23/05/2005 0:00
Time [date & hour]
Ave
rag
e st
rain
[]
C1 (1675) C2 (1668)
C3 (1676) C4 (1669)
C5 (1663) C6 (1683)
C7 (1670) C8 (1682)
C9 (1662) C10 (1677)
The same contractor, the same design, the same concrete quality
Very similar results!
©SHM Lab, SMARTEC, HDB 27/29Ten-year SHM of high-rise buildings
Conclusions Detected under-loading of column C9 helps designer to
understand real structural behavior and improve modeling Differential settlements detected, localized, and
characterized – small magnitude, doesn't influence the performance of building; settlement is however not stabilized yet and monitoring should continue
The 48-hours sessions confirmed sound performance of the building in long-term and made possible post-tremor analysis (no need to evacuate the building due to event)
The creep and shrinkage stabilizes slowly (creep developed ~97% and shrinkage ~84% approximately) and dominant influence is ambient temperature
Quality control performed by comparison of behavior of different building
©SHM Lab, SMARTEC, HDB 28/29Ten-year SHM of high-rise buildings
Conclusions, continued Enlarged knowledge concerning the real column behavior
during construction (rheological effects) In spite of limitations (temperature not monitored, no
continuous readings) results leads to important insights on actual behavior
Pioneer monitoring project for Singapore high-rise buildings: 10-years long-term monitoring successfully performed and important stages in structure life registered
Monitoring method developed and successfully applied, monitoring system was properly selected and fully responded to design criteria
10 out of 10 long-gauge fiber optic sensors properly function after 10+ years
©SHM Lab, SMARTEC, HDB 29/29Ten-year SHM of high-rise buildings
Punggol acknowledgements
Sofotec Singapore Pte Ltd