shakelib.conversions.imt.newmark_hall_1982

class shakelib.conversions.imt.newmark_hall_1982.NewmarkHall1982[source]

Bases: object

Class for conversion between PGA and PSA10 by Newmark and Hall (1982).

  • PSA10 stands for spectral acceleration with oscillator period of 1.0 sec
  • PGV is peak ground velocity.

The conversion factor is 37.27*2.54. Note that 2.54 is the conversion factor to convert from cm/s to in/s and 37.27 is derived from SA(f) = 1.65*(2*pi*V*f)/386.09, where:

  • SA(f) is spectral acceleration at frequency f (in g)
  • f is the frequency of interest
  • V is the velocity
  • 1.65 is the N&H amplification factor for velocity at 5% damping
  • 386.09 is the acceleration of gravity in inches per second per g

The sigma factor was computed from an average sigma value determined by plotting PGV/PSA10 versus Distance for earthquakes with magnitudes greater than or equal to 5.0.

To do
  • Inherit from ConvertIMT class.

References

Newmark, N. M., & Hall, W. J. (1982). Earthquake spectra and design. Earthquake Engineering Research Institute, El Cerrito, California.

static psa102pgv(psa10, sigma)[source]

Convert PSA10 (spectral acceleration with oscillator period of 1.0 sec) to PGV.

Important: PSA10 and sigma must be logarithmic units.

Parameters:
  • psa10 – Numpy array or float of PSA10 values; units must be natural log of g.
  • sigma – Numpy array or float of standard deviation of PGV from a GMPE; units must be natural log.
Returns:

Two arrays
  • Array of PGV iwth natural log of cm/s units.
  • Array of its standard deviation with natural log units.
static getConversionFactor()[source]
Returns:The Newmark and Hall (1982) multiplicative conversion factor for convering Sa(1.0) to PGV (cm/s).
static getLnSigma()[source]
Returns:The the estimate of the logarithmic standard deviation of the PGV predicted by Newmark and Hall (1982).