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NEESR-SG Seismic Performance Assessment and Retrofit of Non-Ductile RC Frames with Infill Walls

George E. Brown, Jr. Network for Earthquake Engineering Simulation. NEESR-SG Seismic Performance Assessment and Retrofit of Non-Ductile RC Frames with Infill Walls. P. Benson Shing, Jose Restrepo, and Andreas Stavridis University of California, San Diego.

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NEESR-SG Seismic Performance Assessment and Retrofit of Non-Ductile RC Frames with Infill Walls

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  1. George E. Brown, Jr. Network for Earthquake Engineering Simulation NEESR-SGSeismic Performance Assessment and Retrofit of Non-Ductile RC Frames with Infill Walls P. Benson Shing, Jose Restrepo, and Andreas Stavridis University of California, San Diego Kaspar Willam, Sivaselvan Mettupalayam, and Ben Blackard University of Colorado, Boulder Sarah Billington and Marios Kyriakides Stanford University NEES Annual Meeting

  2. Performance Issues 2000 Kocaeli, Turkey Earthquake (EERI) • Non-uniform infill – • open bottom story • Asymmetric stiffening • introducing torsion NEES Annual Meeting

  3. Bare Frame Infilled Frame Beneficial Influence of Infill Negro et al. (1996) NEES Annual Meeting

  4. Main Issue • Brittle shear failure of columns • Strength degradation of infill and columns leading to soft story mechanism Soft Story NEES Annual Meeting

  5. Questions to be Answered • What is the threshold ground motion level beyond which an infilled frame will have undesirable performance? • How can we raise this threshold with cost-effective strengthening? NEES Annual Meeting

  6. State of the Practice • Lack of reliable analysis tools for sound engineering decisions • Contribution of infill walls to seismic resistance difficult to assess • Lack of proven cost-effective strengthening methods for infill walls NEES Annual Meeting

  7. Complicated Failure Mechanisms NEES Annual Meeting

  8. Frame-Panel Interaction Frames Tested by Mehrabi et al. (1994) Strong Infill Weak Infill NEES Annual Meeting

  9. Project Deliverables • Improved analysis methods for performance assessment • Rational assessment procedure considering contribution of infill walls • Validated cost-effective strengthening methods to enhance system-level performance NEES Annual Meeting

  10. Improved Analysis Methods Assessment of Existing Modeling Methods Small-Scale Tests on Strengthening Methods Large-Scale Tests on Multi-Story Frames Medium-Scale Tests on Single-Story Frames Component Performance System Performance Retrofit Methods Research Approach NEES Annual Meeting

  11. Performance Assessment Does the building need strengthening considering the contribution of infill walls? No Done Yes Can it be economically and adequately strengthened without additional load resisting systems? Yes No Infill and/or column strengthening Addition of new loading resisting systems Rational Assessment Procedure NEES Annual Meeting

  12. Retrofit Methods • Engineered Cementitious Composites (ECC) for infill strengthening • FRP overlay or spray • Infill wall-to-beam connection • Column strengthening NEES Annual Meeting

  13. A ECC Overlay (Stanford U.) ECC Shear connector A-A A NEES Annual Meeting

  14. Small-Scale Tests at Stanford In-plane Wall Tests Prism Tests Flexural Tests NEES Annual Meeting

  15. 2/3-Scale Single-Story Frame Tests(Colorado NEES Site) NEES Annual Meeting

  16. Tentative Test Matrix for Single-Story Specimens NEES Annual Meeting

  17. Full-Scale Shake Table Tests(UCSD NEES Site) • Frame with solid infill. • Frame with solid infill and retrofit. • Frame with infill openings and retrofit. NEES Annual Meeting

  18. Analysis Methods • Advanced computational models for detailed analysis (CU-Boulder) • Limit analysis methods accounting for multiple failure scenarios • Simplified strut models for time histories analysis NEES Annual Meeting

  19. Evaluation of Existing Models Tests by Mehrabi et al. (1994) NEES Annual Meeting

  20. Stanford: DIANA Colorado: ABAQUS UCSD: FEAP Comparison of Programs FEAP Crack and Crushing DIANA Principal Tensile Strain NEES Annual Meeting

  21. Axial Compression Shear Infill Joint Modeling with FEAP Element Failure Surface NEES Annual Meeting

  22. Infilled Frame Analysis (FEAP) NEES Annual Meeting

  23. Additional Modeling Work • Parametric studies to examine influence of model parameters • Calibration of simplified analytical models • Predictive analysis and assessment with new experimental results • Model improvement NEES Annual Meeting

  24. Project Team Benson Shing Jose Restrepo Andreas Stavridis Kaspar Willam Sivaselvan Mettupalayam Ben Blackard Sarah Billington Marios Kyriakides Rutherford & Chekene Joe Maffei Bill Holmes Bret Lizundia NEES Annual Meeting

  25. Professional Advisory Panel • Joe Maffei, R&C (Chair) • Dave Brieholz, BQE • John Kariotis, K&A • Ron Mayes, SGH • Paul Murray, PSDG • Mike Valley, MKA • Greg Kingsley, KLA Ron Hamburger, SGH NEES Annual Meeting

  26. Thank You NEES Annual Meeting

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