NEES Aftershock Monitoring of Reinforced Concrete Buildings in Santiago, Chile
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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)

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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 ([email protected] co-PI & Manager)

Derek Skolnik (Sr. Project Engineer, Kinemetrics)

John Wallace (Professor, UCLA and [email protected] PI)

Preparation of Instrumentation Layouts

Equipment provided by [email protected]

Instrumentation used:

Arrival at the Santiago Airport on March 13

Instrumented Buildings

  • 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

Located in Santiago, Chile

Ambient Vibration

Ambient Vibration

2 Aftershocks

Ambient Vibration

30 Aftershocks

Ambient Vibration

4 Aftershocks

Chile RAPID Instrumentation Team

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 :

MatiasChacom, (Pontificia Universidad Católica de Chile)

Javier Encina, (Pontificia Universidad Católica de Chile)

Joao Maques, (Pontificia Universidad Católica de Chile)

Local Faculty Collaborators

Juan C. De La Llera M. (Pontificia Universidad Católica de Chile)

Leonardo Massone (University of Chile, Santiago)

CO-PIs on the NSF Rapid Proposal

Robert Nigbor (UCLA)

John Wallace (UCLA)

Building B:

  • -10 story RC residential building

  • - Structural system:

  • Shear Walls

  • Post Earthquake damage:

  • Shear wall failure,

  • Column buckling,

  • Extensive non-structural failure,

  • slab bending & concrete spalling

Observed Damage in the 10 story shear wall building:

Repetitive Damage at the -1 level (Parking level):

Wall-Slab intersections

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




-1 st

Story Displacements




-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

Vertical LVDTs

Diagonal LVDTs

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.

2nd floor responses

Torsion and rocking


3 triaxial sensors

Rocking about the x axis = orientation of shear wall (corresponds to shear wall cracking)

Particle Motion

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)

[email protected] Post Earthquake Collaboration Possibilities

  • [email protected] 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

Instrumentation Layout: Exemplarily for 2nd floor

3 triaxial sensors

9th Floor instrumentation:

3 uniaxial sensors

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

3 triaxial sensors





-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

Accelerations Floor 1 & 10












Center acc were calculated assuming rigid diaphragms and using the following equations:

Max values 1st floor:


Center acc : 1.2 cm/s2

Corner acc: 1.2 cm/s2


Center acc: 1.2 cm/s2

Corner: 1.2 cm/s2

Accelerations Floor 1 & 10

No Torsion

Max values 10th floor:


Center acc : 3.5 cm/s2

Corner acc: 4.3 cm/s2


Center acc: 2.8 cm/s2

Edge: 5.0 cm/s2


Displacements Floor 1 & 10

Max values 1st floor:


Center acc : 0.31 mm

Corner acc: 0.32 mm


Center acc: 0.29 mm

Edge: 0.29 mm

Perfect rigid body motion at 1st floor

Max values 10th floor:


Center acc : 1.15 mm

Corner acc: 1.2 mm


Center acc: 0.74 mm

Edge: 1.24mm

Twisting / Torsion on 10th floor

X-Y Particle motion at slab center

FFTs of Accelerations

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