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Seismic Analysis and Design of Retaining Walls, Buried Structures, Slopes, and Embankments (2008) / Chapter Skim
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Pages 55-67

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From page 55...
... This is followed by a more detailed evaluation of the scattering effects for retaining walls. 6.1.1 Scattering Analyses for a Slope Wave propagation analyses were conducted for an embankment slope that was 30 feet in height and had a 3H:1V (horizontal to vertical)
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From page 56...
... Solutions involving such impedance contrast will, however, be relevant for site-specific cases, as discussed in Chapters 7 and 8 of this Final Report. 6.1.1.2 Earthquake Records Used In Slope Studies Several earthquake time histories were used for input excitation; each one was spectrum matched to lower bound, mid, or upper bound spectra, as discussed in Chapter 5.
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From page 57...
... 6.1.1.3 Results of Scattering Analyses for Slopes Figures 6-3 through 6-5 show comparisons of seismic coefficient time histories (dark lines) against the input outcrop motion (light lines)
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From page 58...
... 1 0.5 0 Bl oc k 1 k -0.5 -1 0 5 10 15 20 25 30 35 1 0.5 0 Bl oc k 2 k -0.5 -1 0 5 10 15 20 25 30 35 1 0.5 0 Bl oc k 3 k -0.5 -1 0 5 10 15 20 Time, s 25 30 35 Input Outcrop Seismic Coeff 1 0.5 0 Bl oc k 1 k -0.5 -1 0 5 10 15 20 25 30 35 1 0.5 0 Bl oc k 2 k -0.5 -1 0 5 10 15 20 25 30 Input Outcrop Seismic Coeff 35 1 0.5 0 Bl oc k 3 k -0.5 -1 0 5 10 15 20 Time, s 25 30 35 Figure 6-4. Scattering results for lower bound spectral shape, Dayhook record.
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From page 59...
... 1 0.5 0 Bl oc k 1 k -0.5 -1 0 5 10 15 20 25 30 35 1 0.5 0 Bl oc k 2 k -0.5 -1 0 5 10 15 20 25 30 35 1 0.5 0 Bl oc k 3 k -0.5 -1 0 5 10 15 20 Time, s 25 30 Input Outcrop Seismic Coeff 35 Figure 6-6. Scattering results for mid spectral shape, Imperial Valley EQ record.
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From page 60...
... 1 0.5 0 Bl oc k 3 k -0.5 -1 0 5 10 15 20 Time, s 25 30 Input Outcrop Seismic Coeff 35 1 0.5 0 Bl oc k 2 k -0.5 -1 0 5 10 15 20 25 30 35 1 0.5 0 Bl oc k 1 k -0.5 -1 0 5 10 15 20 25 30 35 Figure 6-8. Scattering results for mid spectral shape, San Fernando EQ record.
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From page 61...
... Input Outcrop Seismic Coeff 1 0.5 0 Bl oc k 3 k -0.5 -1 0 5 10 15 Time, s 20 25 30 35 1 0.5 0 Bl oc k 2 k -0.5 -1 0 5 10 15 20 25 30 35 1 0.5 0 Bl oc k 1 k -0.5 -1 0 5 10 15 20 25 30 35 Figure 6-10. Scattering results for upper bound spectral shape, Turkey EQ record.
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From page 62...
... Scattering results for upper bound spectral shape, El Centro EQ record. Input Outcrop Seismic Coeff 1 0.5 0 Bl oc k 3 k -0.5 -1 0 5 10 15 Time, s 20 25 30 35 1 0.5 0 Bl oc k 2 k -0.5 -1 0 5 10 15 20 25 30 35 1 0.5 0 Bl oc k 1 k -0.5 -1 0 5 10 15 20 25 30 35
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From page 63...
... Also, results from the three time histories each matched to the same response spectrum were averaged. The resultant solutions for the α coefficients categorized by wall height and the spectral shapes (that is, upper bound, mid and lower bound spectral shapes)
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From page 64...
... Another justification for designing to a value less than the PGA arises from the fact that many retaining walls are implicitly designed for wall movements when the wall is designed for an active earth pressure condition. The wave scattering analyses in this evaluation were based on linear elastic analyses and further reduction in the force demand is justified when the retaining wall is designed to slide at a specific threshold load level as discussed in Chapter 7.
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From page 65...
... Results of scattering analyses. (continued on next page)
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From page 66...
... . this ratio systematically decreased for increasing wall height and lowering of the spectral shape at long periods.
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From page 67...
... This spectrum is then overlaid on the spectral shape shown on Figure 5-4 to determine the most appropriate spectral curve shape for the design condition. • After selecting the appropriate spectral shape (that is, in terms of UB, Mid, and LB spectral shapes)
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Key Terms

  • scattering results
  • bound spectral
  • apparent wave
  • input outcrop
  • spectral shape

  • outcrop motion
  • wave speed
  • bound spectrum
  • imperial valley
  • lower bound

  • upper bound
  • scattering analyses
  • time history
  • mid spectral
  • wave passage

  • wave propagation
  • bound spectra
  • efficient time
  • dark lines
  • light lines

  • relative peaks
  • soil mesh
  • horizontal direction
  • seismic coefficient
  • retaining walls

  • spectral curve
  • wave scattering
  • earth pressure
  • analyses included


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