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Nonlinear response-history analysis in design practice

Nonlinear response-history analysis in design practice. November 2007 Joe Maffei. RUTHERFORD & CHEKENE. RUTHERFORD & CHEKENE. RUTHERFORD & CHEKENE. Why do NLRH?. The code makes us. (Base isolation or supplemental damping) Substantiation of non-prescriptive (“alternative”) designs.

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Nonlinear response-history analysis in design practice

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  1. Nonlinear response-history analysis in design practice November 2007 Joe Maffei RUTHERFORD & CHEKENE

  2. RUTHERFORD & CHEKENE

  3. RUTHERFORD & CHEKENE

  4. Why do NLRH? • The code makes us. (Base isolation or supplemental damping) • Substantiation of non-prescriptive (“alternative”) designs. • We want to know what happens. What is the value of NLRH?

  5. Outline • Example projects • Unique value of NLRH • Findings from NLRH of tall buildings • Dispersion of NLRH results • Ground motion input • Conclusions • [Modeling uncertainty]

  6. Example projects that used NLRH

  7. RUTHERFORD & CHEKENE

  8. RUTHERFORD & CHEKENE

  9. Education Tower

  10. RUTHERFORD & CHEKENE

  11. Buildings with supplemental damping RUTHERFORD & CHEKENE

  12. Waterfront pier structures

  13. Exploratorium – Piers 15 and 17 RUTHERFORD & CHEKENE

  14. Non-prescriptive seismic design

  15. ROOF 13th BASE

  16. What is the unique value of NLRH? …

  17. To determine what happens, not how much. Desired mechanism Undesirable mechanism RUTHERFORD & CHEKENE

  18. Findings from NLRH analyses of high-rise buildings

  19. Runs scaled from 0.1x MCE to 4x MCE

  20. Runs scaled from 0.1 x MCE to 4 x MCE

  21. Core wall moment versus shear amplification

  22. Moment to shear ratio • 110’ at 0.6x MCE • 90’ at MCE • 57’ at 2x MCE • 230’ • 175’

  23. Use NLRH to determine what happens, more than how much. RUTHERFORD & CHEKENE

  24. Coupled wall Plastic hinge locations RUTHERFORD & CHEKENE

  25. RUTHERFORD & CHEKENE

  26. Dispersion of results among 7 or 14 ground motion records

  27. 14 NLRH RUNS ROOF 13th BASE

  28. Coupling beam rotation

  29. Considering dispersion • “Demands for ductile actions shall be taken not less than the mean value obtained from the NLRH. Demands for low-ductility actions (e.g., axial and shear response of columns and shear response of walls) shall consider the dispersion of the values obtained from the NLRH.”

  30. NLRH ground motion input

  31. NLRH INPUT • 7 horizontal ground motion pairs • 14 response-history runs GRN 180 GRN 270 GRN 180 GRN 270 RUTHERFORD & CHEKENE

  32. NLRH analysis at MCE • “When the ground motion components [statistically] represent site-specific fault-normal ground motions and fault-parallel ground motions, the components shall be applied to the three-dimensional mathematical analysis model according to the orientation of the fault with respect to the building. When the ground motion components represent random orientations, the components shall be applied to the model at orientation angles that are selected randomly; individual ground motion pairs need not be applied in multiple orientations. .”

  33. NLRH analysis at MCE • “Where applicable, an appropriate number of the ground motion time series shall include near fault and directivity effects such as velocity pulses producing relatively large spectral ordinates at relatively long periods.”

  34. Conclusions

  35. The most important value of NLRH is that it tells you what the nonlinear mechanism is, and what the overstrength forces are on elements that you want to remain elastic. RUTHERFORD & CHEKENE

  36. Modeling uncertainty

  37. Olivian

  38. Comparison of SAP model by KPFF vs Perform model by R&C

  39. EQ4: Test EQ4PGA = 0.93g

  40. EQ4:

  41. Experimental results EQ3: Essentially linear EQ4: Non-linear

  42. Measured

  43. 111 Almaden Ave San Jose

  44. Beam connection behavior

  45. Beam fiber model

  46. Analysis model versus test results

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