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)

Preparation of Instrumentation LayoutsEquipment provided by NEES@UCLA

Instrumentation used:

Arrival at the Santiago Airport on March 13

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

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

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

Repetitive Damage at the -1 level (Parking level):Wall-Slab intersections

Observed Damage in the 10 story shear wall building:

1st floor shear wall damage

1st floor shear wall damage

Column buckling at first floor

Shear Wall Instrumentation with LVDTs

Story Accelerations 2010 05/02 14:52:39 UTC M5

40 60 80 100 120

-20

0

20

EW Acceleration

Roo

f (cm

/s2 )

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 (cm

/s2 )

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

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

Shear and Flexure Deformations

Figure 4: Shear-flexure interaction for a wall subject to lateral loading. (adapted from Massone and Wallace, 2004)

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)

Verti

cal L

VD

TsD

iago

nal L

VD

Ts

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)

shearflexure

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

Tors

ion

(rad/

s2 )

Time (s)

40 60 80 100 120-0.04

-0.02

0

0.02

0.04

Roc

king

abo

ut X

(rad

/s2 )

Time (s)

40 60 80 100 120-4

-2

0

2

4x 10

-3

Roc

king

abo

ut Y

(rad

/s2 )

Time (s)

40 60 80 100 120-5

0

5x 10

-5 Displacement

Tors

ion

(rad)

Time (s)

40 60 80 100 120-5

0

5x 10

-4

Roc

king

abo

ut X

(rad

)

Time (s)

40 60 80 100 120-5

0

5x 10

-5

Roc

king

abo

ut Y

(rad

)Time (s)

NOTE CHANGE IN SCALE FOR X- AXIS ROCKING

3 triaxial sensors

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

(mm

)

Roof9th2ndGround

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)

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

Funding Opportunity – 2011 NEES Research RFP~$10M Annually, 2011 Deadline March 9www.nees.org/neesrproposalonestopshop

Instrumentation Layout: Exemplarily for 2nd floor

3 triaxial sensors

3 uniaxial sensors

9th Floor instrumentation:

Floor Plan: Ground Floor (-1 Level)

Instrumentation on Ground Level:

Triaxial sensor

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

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

FFTs

0 1 2 3 4 50

0.5

1

1.5

2

2.5

3

3.5

4x 10

4

FFT

EW

Freq (Hz)0 1 2 3 4 5

0

0.5

1

1.5

2

2.5

3

3.5

4x 10

4

FFT

NS

Freq (Hz)

Roof

9th

2nd

-1 st

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

Building: Golf 80, Las Condes, Santiago, Chile

The only earthquake damage observed: Minor glass breaking on outside Fassade

Floor plan for typical floor:

Foto’s from the inside: 10th floor

On site notes:

Chilean Seismic Network info for earthquake:

2010-03-26- 14:54:08 UTC

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

10th1st

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 (

rad/

s2 )

Time (s)

Accelerations Floor 1 & 10

v2

u4

v2

u3

v3

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

10th1st

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 (

rad/

s2 )

Time (s)

Accelerations Floor 1 & 10

No Torsion

Torsion

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 mmPerfect 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 (

rad)

Time (s)

10th1st

Displacements Floor 1 & 10

X-Y Particle motion at slab center

-1 -0.5 0 0.5 1

-1

-0.5

0

0.5

1

EW (mm)

NS

(mm

)

10th1st

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

0.4To

r 10

Freq (Hz)