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Practices and Procedures for Site-Specific Evaluations of Earthquake Ground Motions (2012) / Chapter Skim
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Pages 19-23

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From page 19...
... As indicated in the survey responses, the equivalent-lin ear site response analysis method is, by far, the most widely used method for evaluation of site-specific ground motions. Advantages of the equivalent-linear method include its requirement for few, well-understood, input parameters, broad experience with its application, a large publicly avail able database of input parameters, and minimal computa tional effort.
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From page 20...
... Cyclic hysteretic soil behavior during unloading and reload · Equivalent-linear analysis is a total-stress analysis; ing is also represented in the nonlinear site response anal hence, it does not account for pore pressure generation ysis. Furthermore, nonlinear analysis makes it possible to and its effect on material properties during shaking; explicitly include soil strength and the effects of seismic · This method is not recommended when the levels of pore water pressure generation on soil strength and stiff shaking-induced shear strains are "high." There is no ness.
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From page 21...
... . Nonlinear total stress site response analysis is generally done with relatively simplified soil constitutive models.
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From page 22...
... and extended Masing rules (MRD) in terms SPECTRA, a 1-D nonlinear total stress site response analyof overestimation of damping at large strain levels (MR at sis program that uses a bounding surface plasticity model strains > 0.1%; MRD at strains > 1%)
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From page 23...
... and m and k are elements of the mass and stiffness matrices, respectively. NONLINEAR SITE RESPONSE ANALYSIS WITH PORE WATER PRESSURE CHANGE Figure 8 illustrates how Rayleigh damping, expressed through c, changes with frequency.
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Key Terms

  • site response
  • liquefiable soils
  • response analysis
  • time histories
  • pore pressure

  • ground acceleration
  • ground motions
  • soil models
  • nonlinear total
  • soft soils

  • ground response
  • ground motion
  • peak ground
  • response analyses
  • input ground

  • monte carlo
  • total stress
  • damping curves
  • masing rules
  • shear wave

  • pore water
  • modulus reduction
  • shear stress
  • water pressure
  • pressure generation

  • wave velocity
  • effective stress
  • motion time
  • pwp generation
  • extended masing


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