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Presented by Anne Lemnitzer

Aftershock Monitoring of Reinforced Concrete Buildings in Santiago, Chile following the February 27, 2010 Mw=8.8 Earthquake. Presented by Anne Lemnitzer. Project Collaborators and Contributors: Derek Skolnik (Sr. Project Engineer, Kinemetrics)

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Presented by Anne Lemnitzer

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  1. Aftershock Monitoring of Reinforced Concrete Buildings in Santiago, Chile following the February 27, 2010 Mw=8.8 Earthquake Presented by Anne Lemnitzer Project Collaborators and Contributors: Derek Skolnik (Sr. Project Engineer, Kinemetrics) Aziz Akhtary (Grad Student Researcher, CSU Fullerton) Leonardo Massone (Assist. Prof. , Univ. of Chile, Santiago) Juan Carlos de la Llerra (Dean, Catholic University of Chile, Santiago) John Wallace (Professor, UCLA) Anne Lemnitzer (Assist. Prof, Cal State Fullerton)

  2. Preparation of Instrumentation Layouts Equipment provided by NEES@UCLA Instrumentation used:

  3. Arrival at the Santiago Airport

  4. High Tech Luggage Scanning

  5. Instrumented Buildings • Buildings selected based on: • - Access and permission • 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 2 Aftershocks Ambient Vibration 30 Aftershocks Ambient Vibration 4 Aftershocks

  6. Building A: • -23 story RC office building in Santiago’s • Business district • Structural system: • 2 inner cores with surrounding frame • - Post Earthquake structural damage: None

  7. Instrumentation Layout: Level 1: N Glass-facade Elevators Roof: Stairway Elevators DAQ

  8. 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

  9. Observed Damages in the 10 story shear wall building: Repetitive Damage at the -1 level (Parking level): Wall-Slab intersections

  10. 1st floor shear wall damage

  11. 1st floor shear wall damage

  12. 1st floor shear wall damage

  13. Column buckling at first floor

  14. Floor Plan: Ground Floor (-1 Level)

  15. Instrumentation on Ground Level: Triaxial sensor

  16. 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

  17. Shear Wall Instrumentation

  18. Instrumentation Layout: Exemplarily for 2nd floor 3 triaxial sensors

  19. 9th Floor instrumentation: 3 uniaxial sensors

  20. Selected aftershock: 2010 05/02 14:52:39 UTC Earthquake info Chilean Seismic Network

  21. Story Accelerations Roof 9th 2nd -1 st

  22. Story Displacements Roof 9th 2nd -1 st

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

  24. LVDT Measurements Vertical LVDTs Diagonal LVDTs

  25. 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.

  26. 2nd floor responses 3 triaxial sensors

  27. 2nd floor responses Torsion and rocking NOTE CHANGE IN SCALE FOR X- AXIS ROCKING 3 triaxial sensors Rocking about the x axis = orientation of shear wall (corresponds to shear wall cracking)

  28. Particle Motion

  29. FFTs Roof 9th 2nd -1 st

  30. Future Studies for the Shear Building • Analysis of more aftershock measurements (Stronger intensities) • Transfer Functions • Further Analysis of Modal Components • Building modeling in commercially available software (e.g., SAP 2000 and others) • Provide data for shear wall research (cyclic model studies)

  31. 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

  32. Building: Golf 80, Las Condes, Santiago, Chile

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

  34. Floor plan for typical floor:

  35. Foto’s from the inside: 10th floor

  36. Chilean Seismic Network info for earthquake: 2010-03-26- 14:54:08 UTC

  37. Accelerations Floor 1 & 10 u2 u1 v0 v1 v2 q0 u0 u4 u3 v2 v3 Center acc were calculated assuming rigid diaphragms and using the following equations:

  38. Max values 1st floor: E_W Center acc : 1.2 cm/s2 Corner acc: 1.2 cm/s2 N_S Center acc: 1.2 cm/s2 Corner: 1.2 cm/s2 Accelerations Floor 1 & 10 No Torsion Max values 10th floor: E_W Center acc : 3.5 cm/s2 Corner acc: 4.3 cm/s2 N_S Center acc: 2.8 cm/s2 Edge: 5.0 cm/s2 Torsion

  39. Displacements Floor 1 & 10 Max values 1st floor: E_W Center acc : 0.31 mm Corner acc: 0.32 mm N_S Center acc: 0.29 mm Edge: 0.29 mm Perfect rigid body motion at 1st floor Max values 10th floor: E_W Center acc : 1.15 mm Corner acc: 1.2 mm N_S Center acc: 0.74 mm Edge: 1.24mm Twisting / Torsion on 10th floor

  40. X-Y Particle motion at slab center

  41. FFTs of Accelerations

  42. Future Steps: • Understanding building modal behavior • Building modeling and more advanced system identification (e.g., transfer functions) to obtain better modal properties (e.g., damping, mode shapes… if possible) • Test rigid diaphragm assumption using sensor redundancy on floors (e.g., comparing floor center motions using different subsets of sensors) • Comprehensive building modeling in SAP 2000 or equivalent software packages • Data sharing at the NEES platform

  43. Lessons Learned • Airport regulations (invitation letters, label equipment as non stationary) • Trigger and record mechanisms (set minimum recording time vs. EQ duration + Dt) • Instrumentation cabling (<100m, Power supplies) • Time Frame (aftershock span) • Local collaboration (building access, installation, translations) • Equipment Transportation (luggage vs shipping) • Take Pictures of every sensor with reference on it….

  44. On Site 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 : Matias Chacom, (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)

  45. Thank you very much

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