1 / 16

Workshop Questions (Nov. 7, 2003)

Workshop Questions (Nov. 7, 2003). For the few near-fault records that include fling response, should these effects be explicitly removed before developing the initial ground motion models? YES How should fling effects be removed? WORK IN PROGRESS.

damian
Download Presentation

Workshop Questions (Nov. 7, 2003)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. NGA Workshop: Fling

  2. Workshop Questions (Nov. 7, 2003) • For the few near-fault records that include fling response, should these effects be explicitly removed before developing the initial ground motion models? YES • How should fling effects be removed? WORK IN PROGRESS NGA Workshop: Fling

  3. To model fling we need to accurately recover the residual displacement. Baseline correction of recorded motion is important step. NGA Workshop: Fling

  4. Although the results look physically plausible, the residual displacements can be sensitive to t1, t2Quadratic fit to velocity gives best fit to GPS residual displacementin this case NGA Workshop: Fling

  5. TCU068 displacement record baseline corrected using Boore’s method (modified Iwan) with three choices of t2. For this record there is not much sensitivity to the choice of t2. t1: acc > 50 cm/sec2 t2(1): Boore v0 t2(2): acc < 50 cm/sec2 t2(3): 2 x t2(2) – t1 NGA Workshop: Fling

  6. NGA Workshop: Fling

  7. Sine-pulse fits to the three corrected displacement records. The pulse start times are all very close (33.24, 33.36, 33.42) as are the pulse periods (4.39, 4.12, 3.83). The main difference are the final displacements (617, 570, 528). NGA Workshop: Fling

  8. Spectral acceleration for the three tcu068 records with the sine-pulse removed, compared with SA for the original (I.e., with fling) record (magenta line). 1) There is some sensitivity to t2 between 2 and 5 sec period (difference btw red, green and black lines). Max. difference is about 60%. 2) There is a large difference compared to original record, with the fling-removed records actually being much larger than the original record up to about 6-7 sec period. NGA Workshop: Fling

  9. Similar analysis for tcu052 record. The sensitivity of baseline correction to t2 is greater than for tcu068. However, the sensitivity in SA for the fling-removed records is less. NGA Workshop: Fling

  10. NGA Workshop: Fling

  11. NGA Workshop: Fling

  12. NGA Workshop: Fling

  13. NGA Workshop: Fling

  14. NGA Workshop: Fling

  15. NGA Workshop: Fling

  16. Conclusions • Baseline correction of raw record must be done with care. • Sine-pulse model for fling is attractive because it provides a time domain parameterization and can be related to the underlying physical process. • Response spectra for sine-pulse corrected records can show sensitivity to choice of processing parameters- • Is this acceptable? (9 m disp. at TCU068) NGA Workshop: Fling

More Related