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Presented by Bob Nigbor

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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Presented by Bob Nigbor

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  1. 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)

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

  3. Arrival at the Santiago Airport on March 13

  4. 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

  5. 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)

  6. 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

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

  8. 1st floor shear wall damage

  9. 1st floor shear wall damage

  10. Column buckling at first floor

  11. Shear Wall Instrumentation with LVDTs

  12. Story Accelerations 2010 05/02 14:52:39 UTC M5 Roof 9th 2nd -1 st

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

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

  15. LVDT Measurements Vertical LVDTs Diagonal LVDTs

  16. 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.

  17. 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)

  18. Particle Motion

  19. 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)

  20. 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

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

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

  23. 9th Floor instrumentation: 3 uniaxial sensors

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

  25. Instrumentation on Ground Level: Triaxial sensor

  26. 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

  27. 2nd floor responses 3 triaxial sensors

  28. FFTs Roof 9th 2nd -1 st

  29. 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

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

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

  32. Floor plan for typical floor:

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

  34. On site notes:

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

  36. 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:

  37. 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

  38. 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

  39. X-Y Particle motion at slab center

  40. FFTs of Accelerations

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