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Seismic Fragility Assessment of SCED Brace System us ing Hybrid Simulation

Seismic Fragility Assessment of SCED Brace System us ing Hybrid Simulation. Oh-Sung Kwon Assistant Professor Viswanath Kammula MASc student Constantin Christopoulos Associate Professor Jeff Erochko PhD student. July 12, 2012. Outline. Seismic Fragility Function

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Seismic Fragility Assessment of SCED Brace System us ing Hybrid Simulation

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  1. Seismic Fragility Assessment of SCED Brace System using Hybrid Simulation Oh-Sung Kwon Assistant Professor Viswanath Kammula MASc student Constantin Christopoulos Associate Professor Jeff Erochko PhD student July 12, 2012

  2. Outline • Seismic Fragility Function • Reference Structure • Hybrid Simulation Configuration • Experimental Results • Summary

  3. 1.0 0.8 0.6 Probability 0.4 0.2 0.0 0 0.05 0.10 0.15 0.20 0.25 Seismic Intensity (PGA, g) P IM Seismic Risk/Loss Assessment Scio-eco. impact Damage prediction Hazard Fragility functions Inventorydata

  4. Seismic Fragility Functions • Development of Seismic Fragility Functions • Empirical – post-earthquake survey • Judgmental – experts’ opinion • Analytical – numerical analysis of structures • Hybrid (combination of above) • Most Common Methods in Industry • Leading catastrophe modeling industries: EQECAT, AIR Worldwide, RMS • Methods: analysis, empirical, judgmental methods

  5. Median D at each IM are independent Identical dispersion 0.11 0.10 0.09 Failure peak acceleration, g 0.08 0.07 0.06 400 45 350 40 35 300 30 25 Steel strength, fy 250 20 Concrete strength, fc Seismic Fragility Functions • Analytical Derivation of Seismic Fragility Functions • Monte-Carlo simulation • SAC-FEMA based approach • Response surface method Regardless of the method, analytical derivation highly depends on the accuracy of analytical prediction.

  6. Seismic Fragility Functions • Analytical Prediction of Structural Response 3D Analysis Blind Prediction Results (measured and best 3 teams of each category) Collapse test of a full-scale four story steel building , 2007 http://www.blind-analysis.jp/2008/2007/index_e.html

  7. Seismic Fragility Functions • Analytical Prediction of Structural Response Prediction of structural behaviour using NLTH is still very challenging and depends on many assumptions in the numerical model. Concrete column blind prediction contest, 2010 http://nisee2.berkeley.edu/peer/prediction_contest/

  8. UI-SIMCOR Vector 2 Matlab MUST-SIM Facility, UIUC Hybrid (Analysis-Experiment) Simulation • Critical component can be physically tested in hybrid simulation FEDEASLab Experiment Hybrid simulation can reduce the gap between analytical prediction and actual behavior by representing critical component(s) experimentally.

  9. Objective • To develop seismic fragility functions of a structure with Self-Centering Energy-Dissipative (SCED) Braces using hybrid simulation

  10. Outline • Seismic Fragility Function • Reference Structure • Hybrid Simulation Configuration • Experimental Results • Current Research and Development in University of Toronto

  11. Self-Centering Systems • Characterized with ‘flag-shape’ hysteresis loop • Minimal residual deformation with energy dissipation capacity • Damage-free structural system • Self-centering moment resisting steel frame (Christopoulos et al. 2002, Herning et al. 2009) • Controlled rocking steel frame (Eatherton et al. 2010) • Segmental bridge bents (ElGawady and Sha’lan 2011) • Self-centering braces (Christopoulos et al. 2008) among many others.

  12. SCED Brace System • Christopoulos, C., Tremblay, R., Kim, H.-J., and Lacerte, M. (2008). “Self-Centering Energy Dissipative Bracing System for the Seismic Resistance of Structures: Development and Validation.” Journal of Structural Engineering, 134(1), 96.

  13. Reference Structure • Six-storey Steel Frame • Designed with ASCE 7-05 • Assumed R-factor of 7 (brace system) • Los Angeles, CA • Design Sa = 1.4g, MCE Sa = 2.1g

  14. Reference Structure • Six-storey Steel Frame • Designed with ASCE 7-05 • Assumed R-factor of 7 (brace system) • Los Angeles, CA • Design Sa = 1.4g, MCE Sa = 2.1g SCED braces Gravity column

  15. Identical dispersion Input Ground Motions • SAC-FEMA Method for fragility analysis • Ground motions • Far-field motions from PEER-NGA Database • Wide range of Sa at fundamental period of the structure • Total thirty ground motions for hybrid simulation • Scale factors of 0.65 ~ 1.1 are used to ensure that Sa are widely distributed • Ground motions are truncated to reduce simulation time

  16. Outline • Seismic Fragility Function • Reference Structure • Hybrid Simulation Configuration • Experimental Results • Current Research and Development in University of Toronto

  17. Hybrid Simulation Configuration a) Whole Model d) OpenSees c) Specimen b) UI-SimCor Note: Gravity columns are included but not illustrated in the above figure. SCED brace is a main lateral load resisting system.

  18. Hybrid Simulation Configuration UI-SimCor Displacement feedback NE T WORK Force feedback PID Control Loop NI ComactDAQ MTS FlexTest Controller MTS Actuator Specimen NICON Command Command Command USB Voltage Action Analysis Result Measurement NICA OpenSees PIPE ACTIA USB

  19. Hybrid Simulation Configuration Ph.D. research of J. Erochko, Advisor: Prof. C. Christopoulos

  20. Hybrid Simulation Configuration Ph.D. research of J. Erochko, Advisor: Prof. C. Christopoulos

  21. Static Cyclic Test • Challenges • Slackness in loading frame • Implemented control algorithm based on external feedback

  22. Outline • Seismic Fragility Function • Reference Structure • Hybrid Simulation Configuration • Experimental Results • Current Research and Development in University of Toronto

  23. Simulation Results Whittier Narrows-01, 1987, Brea Dam Loma Prieta, 1989, Gilroy Array#2

  24. Simulation Results Difference in response was due to idealization of brace behavior with flag shape.

  25. Simulation Results • Seismic Demand

  26. Simulation Results • Seismic Fragility Curves Design EQ Maximum Credible EQ

  27. Summary • Seismic fragility functions of a structure with SCED braces are developed using hybrid simulations. • The structure, designed with ASCE 7-05, satisfied inter-story drift limits in ASCE 41. • This conclusion is preliminary, though, as the R factor in ASCE 7 and performance limit in ASCE 41 are not calibrated for SCED braces. • Research is in progress to develop strategy for element selection and model updating.

  28. Thank you!

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