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NEES Aftershock Monitoring of Reinforced Concrete Buildings in Santiago, Chile
following the February 27, 2010 Mw=8.8 Earthquake
Presented by
Bob Nigbor
Project Collaborators and Contributors:Aziz Akhtary (Grad Student Researcher, CSU Fullerton)Juan Carlos de la Llerra (Dean, Catholic University of Chile, Santiago)Anne Lemnitzer (Assist. Prof, Cal State Fullerton)Leonardo Massone (Assist. Prof. , Univ. of Chile, Santiago)Bob Nigbor (NEES@UCLA co-PI & Manager)Derek Skolnik (Sr. Project Engineer, Kinemetrics)John Wallace (Professor, UCLA and NEES@UCLA PI)
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Preparation of Instrumentation LayoutsEquipment provided by NEES@UCLA
Instrumentation used:
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Arrival at the Santiago Airport on March 13
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Instrumented BuildingsLocated in Santiago, Chile
Buildings selected based on:- Access and permission- EERI Recon Team input- Typical design layouts representative for Chile and the US- Local collaborator for building selection: Juan Carlos de la Llerra
Ambient Vibration2 Aftershocks
Ambient Vibration30 Aftershocks
Ambient Vibration4 Aftershocks
Ambient Vibration
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US Team Members:Anne Lemnitzer (CSUFullerton)Alberto Salamanca (NEES @ UCLA)Aditya Jain (Digitexx)Marc Sereci (Digitexx; EERI team member)John Wallace (UCLA, Instrumentation PI)
Local Graduate Student Members :Matias Chacom, (Pontificia Universidad Católica de Chile)Javier Encina, (Pontificia Universidad Católica de Chile)Joao Maques, (Pontificia Universidad Católica de Chile)
Local Faculty CollaboratorsJuan C. De La Llera M. (Pontificia Universidad Católica de Chile)Leonardo Massone (University of Chile, Santiago)
CO-PIs on the NSF Rapid ProposalRobert Nigbor (UCLA)John Wallace (UCLA)
Chile RAPID Instrumentation Team
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Building B:
-10 story RC residential building- Structural system: Shear Walls- Post Earthquake damage: I. Shear wall failure, II. Column buckling, III. Extensive non-
structural failure, IV. slab bending &
concrete spalling
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Repetitive Damage at the -1 level (Parking level):Wall-Slab intersections
Observed Damage in the 10 story shear wall building:
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1st floor shear wall damage
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1st floor shear wall damage
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Column buckling at first floor
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Shear Wall Instrumentation with LVDTs
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Story Accelerations 2010 05/02 14:52:39 UTC M5
40 60 80 100 120
-20
0
20
EW Acceleration
Roo
f (c
m/s
2 )
40 60 80 100 120
-20
0
20
9th
(cm
/s2 )
40 60 80 100 120
-20
0
20
2nd
(cm
/s2 )
40 60 80 100 120
-20
0
20
Grn
d (c
m/s
2 )
40 60 80 100 120
-20
0
20
NS Acceleration
Roo
f (c
m/s
2 )
40 60 80 100 120
-20
0
20
9th
(cm
/s2 )
40 60 80 100 120
-20
0
20
2nd
(cm
/s2 )
40 60 80 100 120
-20
0
20
Grn
d (c
m/s
2 )
Roof
9th
2nd
-1 st
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Story Displacements
40 60 80 100 120
-2
0
2
EW Displacement
Roo
f (m
m)
40 60 80 100 120
-2
0
2
9th
(mm
)
40 60 80 100 120
-2
0
2
2nd
(mm
)
40 60 80 100 120
-2
0
2
Grn
d (m
m)
40 60 80 100 120
-2
0
2
NS Displacement
Roo
f (m
m)
40 60 80 100 120
-2
0
2
9th
(mm
)
40 60 80 100 120
-2
0
2
2nd
(mm
)
40 60 80 100 120
-2
0
2
Grn
d (m
m)
Roof
9th
2nd
-1 st
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Shear and Flexure Deformations
Figure 4: Shear-flexure interaction for a wall subject to lateral loading. (adapted from Massone and Wallace, 2004)
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LVDT Measurements
40 60 80 100 120
-0.1
0
0.1
LVD
T D
isp
(mm
)
Time (s)40 60 80 100 120
-0.1
0
0.1
LVD
T D
isp
(mm
)
Time (s)
40 60 80 100 120
-0.1
0
0.1
LVD
T D
isp
(mm
)
Time (s)40 60 80 100 120
-0.1
0
0.1LV
DT
Dis
p (m
m)
Time (s)
Ver
tical
LV
DTs
Dia
gona
l LV
DTs
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Shear and flexure deformations
The rotation for flexure was taken at the base of the wall (so the top displacement is multiplied by the wall height), which is the largest value expected for flexure. If we assume that the flexure corresponds to a rotation at wall mid-height, the flexural component should be multiplied by 0.5.
30 40 50 60 70 80 90 100 110 120
-0.2
-0.15
-0.1
-0.05
0
0.05
0.1
0.15
0.2W
all t
op D
isp
(mm
)
Time (s)
shear
flexure
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2nd floor responses
Torsion and rocking
Rocking about the x axis = orientation of shear wall (corresponds to shear wall cracking)
40 60 80 100 120-4
-2
0
2
4x 10
-3 Acceleration
Tor
sion
(ra
d/s2 )
Time (s)
40 60 80 100 120-0.04
-0.02
0
0.02
0.04
Roc
king
abo
ut X
(ra
d/s2 )
Time (s)
40 60 80 100 120-4
-2
0
2
4x 10
-3
Roc
king
abo
ut Y
(ra
d/s2 )
Time (s)
40 60 80 100 120-5
0
5x 10
-5 Displacement
Tor
sion
(ra
d)
Time (s)
40 60 80 100 120-5
0
5x 10
-4
Roc
king
abo
ut X
(ra
d)
Time (s)
40 60 80 100 120-5
0
5x 10
-5
Roc
king
abo
ut Y
(ra
d)
Time (s)
NOTE CHANGE IN SCALE FOR X- AXIS ROCKING
3 triaxial sensors
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Particle Motion
-2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
2.5
EW (mm)
NS
(m
m)
Roof
9th2nd
Ground
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Lessons Learned in Chile & Turkey Deployments
Airport regulations (invitation letters, label equipment as non stationary)
Trigger and record mechanisms (Continuous for short duration, triggered for longer)
Instrumentation cabling (<100m, Power supplies)
Time Frame (ambient + aftershocks, can be 1-day or months)
Battery power is workable Local collaboration essential (building access,
installation, translations)
Equipment Transportation (baggage is simple if possible)
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NEES@UCLA Post Earthquake Collaboration Possibilities
• NEES@UCLA can mobilize quickly – 2 weeks this first time
• Cost is subsidized by NEES O&M funding (Chile RAPID was $29k)
• Recommended as a resource for EERI LFE
• We have prepared two 24-channel SHM Systems for rapid deployment• 8 triaxial EpiSensors• 4 Q330s• Slate field computer or “netbook” PC• Car battery power, batteries in-country• GPS timing• Ethernet connectivity• Fits in 4 50-lb suitecases
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Funding Opportunity – 2011 NEES Research RFP~$10M Annually, 2011 Deadline March 9www.nees.org/neesrproposalonestopshop
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Instrumentation Layout: Exemplarily for 2nd floor
3 triaxial sensors
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3 uniaxial sensors
9th Floor instrumentation:
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Floor Plan: Ground Floor (-1 Level)
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Instrumentation on Ground Level:
Triaxial sensor
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Instrumentation Layout: First Floor (shear wall instrumentation)
Instrumented floors:
- Parking Level (-1) : 1 triaxial sensor- 2nd floor : 3 triaxial sensors- 9th floor : 3 uniaxial sensors- Roof : 3 uniaxial sensors
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2nd floor responses
40 60 80 100 120
-10
0
10
Acceleration
EW
(cm
/s2 )
Time (s)
40 60 80 100 120
-10
0
10
NS
(cm
/s2 )
Time (s)
40 60 80 100 120
-10
0
10
z (c
m/s
2 )
Time (s)
40 60 80 100 120-0.2
-0.1
0
0.1
0.2Displacement
EW
(cm
)
Time (s)
40 60 80 100 120-0.2
-0.1
0
0.1
0.2
NS
(cm
)
Time (s)
40 60 80 100 120-0.2
-0.1
0
0.1
0.2
z (c
m)
Time (s)
3 triaxial sensors
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FFTs
0 1 2 3 4 50
0.5
1
1.5
2
2.5
3
3.5
4x 10
4
FF
T E
W
Freq (Hz)0 1 2 3 4 5
0
0.5
1
1.5
2
2.5
3
3.5
4x 10
4
FF
T N
S
Freq (Hz)
Roof
9th
2nd
-1 st
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Building C: “Golf”
- 10 story office building- Unoccupied except for floors # 2 & 8- Inner core shear wall with outer frame system- No structural damage- 4 parking levels (-1 through -4)- Instrumented floors: 1 & 10- Sensors: 8 accelerometers
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Building: Golf 80, Las Condes, Santiago, Chile
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The only earthquake damage observed: Minor glass breaking on outside Fassade
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Floor plan for typical floor:
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Foto’s from the inside: 10th floor
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On site notes:
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Chilean Seismic Network info for earthquake:
2010-03-26- 14:54:08 UTC
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Center acc were calculated assuming rigid diaphragms and using the following equations:
v1
u2u1
u0
v0
q0
0 10 20 30 40 50 60 70 80 90 100-4
-2
0
2
4
NS
(cm
/s2 )
Time (s)
Acceleration
10th
1st
0 10 20 30 40 50 60 70 80 90 100-4
-2
0
2
4
EW
(cm
/s2 )
Time (s)
0 10 20 30 40 50 60 70 80 90 100-4
-2
0
2
4x 10
-3
Tor
(ra
d/s2 )
Time (s)
Accelerations Floor 1 & 10
v2
u4
v2
u3
v3
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Max values 10th floor:
E_WCenter acc : 3.5 cm/s2Corner acc: 4.3 cm/s2
N_SCenter acc: 2.8 cm/s2Edge: 5.0 cm/s2
Max values 1st floor:
E_WCenter acc : 1.2 cm/s2Corner acc: 1.2 cm/s2
N_SCenter acc: 1.2 cm/s2Corner: 1.2 cm/s2
0 10 20 30 40 50 60 70 80 90 100-4
-2
0
2
4
NS
(cm
/s2 )
Time (s)
Acceleration
10th
1st
0 10 20 30 40 50 60 70 80 90 100-4
-2
0
2
4
EW
(cm
/s2 )
Time (s)
0 10 20 30 40 50 60 70 80 90 100-4
-2
0
2
4x 10
-3
Tor
(ra
d/s2 )
Time (s)
Accelerations Floor 1 & 10
No Torsion
Torsion
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Max values 10th floor:
E_WCenter acc : 1.15 mmCorner acc: 1.2 mm
N_SCenter acc: 0.74 mmEdge: 1.24mm
Max values 1st floor:
E_WCenter acc : 0.31 mmCorner acc: 0.32 mm
N_SCenter acc: 0.29 mmEdge: 0.29 mm
Perfect rigid body motion at 1st floor
Twisting / Torsion on 10th floor
0 10 20 30 40 50 60 70 80 90 100
-0.1
0
0.1
NS
(cm
)
Time (s)
Displacement
0 10 20 30 40 50 60 70 80 90 100
-0.1
0
0.1
EW
(cm
)
Time (s)
0 10 20 30 40 50 60 70 80 90 100-5
0
5x 10
-5
Tor
(ra
d)
Time (s)
10th
1st
Displacements Floor 1 & 10
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X-Y Particle motion at slab center
-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
EW (mm)
NS
(m
m)
10th
1st
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FFTs of Accelerations
0 1 2 3 4 50
20
40
60
NS
1
Freq (Hz)
1st Floor
0 1 2 3 4 50
20
40
60
EW
1
Freq (Hz)
0 1 2 3 4 50
0.005
0.01
0.015
Tor
1
Freq (Hz)
0 1 2 3 4 50
100
200
300
400
500
NS
10
Freq (Hz)
10th Floor
0 1 2 3 4 50
200
400
600
EW
10
Freq (Hz)
0 1 2 3 4 50
0.1
0.2
0.3
0.4T
or 1
0
Freq (Hz)