Site-amplified spectral acceleration using Seyhan & Stewart (2014)

Computes site-amplified spectral acceleration Sa_F using the Seyhan & Stewart (2014) non-linear site factor model. This is the canonical implementation that calls the underlying F_ST17() function.

Usage

SaF_ST17(Sa, pga, Tn, vs30, vref = 760)

Arguments

Sa: numeric vector - rock spectral accelerations at period Tn (g)
pga: numeric vector - peak ground acceleration on rock (g), same length as Sa
Tn: numeric scalar - oscillator period (s)
vs30: numeric scalar - time-averaged shear-wave velocity to 30 m (m/s)
vref: numeric scalar - reference velocity (m/s), default 760

Value

A data.table with columns:

muLnSaF: natural-log mean of amplified Sa
sdLnSaF: natural-log standard deviation of amplified Sa
ID: character string "ST17"

References

Seyhan, E. & Stewart, J.P. (2014) "Semi-empirical nonlinear site amplification from NGA-West2 data and simulations." Earthquake Spectra 30(3):1241–1256. doi:10.1193/063013EQS181M

Examples

library(data.table)
#> 
#> Attaching package: ‘data.table’
#> The following object is masked from ‘package:base’:
#> 
#>     %notin%

# Site amplification for soft soil site
Sa_rock <- c(0.1, 0.2, 0.3, 0.4)
PGA_rock <- c(0.1, 0.1, 0.1, 0.1)

result <- SaF_ST17(
  Sa = Sa_rock,
  pga = PGA_rock,
  Tn = 0.5,      # 0.5s period
  vs30 = 300,    # Soft soil
  vref = 760     # Rock reference
)

print(result)
#>       muLnSaF   sdLnSaF     ID
#>         <num>     <num> <char>
#> 1: -1.9411223 0.2704163   ST17
#> 2: -1.2479751 0.2704163   ST17
#> 3: -0.8425100 0.2704163   ST17
#> 4: -0.5548279 0.2704163   ST17