Estimates the seismic response of sites and slopes from the results of a seismic hazard analysis. For a site, it computes the fundamental period of the soil profile and the amplification of spectral acceleration. For a slope, it computes the fundamental period, the earthquake-induced displacement, and the pseudostatic coefficient that keeps a selected quantile of the displacement within a given limit. Uncertainty in the soil profile and in the ground motion is represented by Monte Carlo samples. Every result is reported with its representative value, its applicable quantiles or dispersion, and the population or conditioning to which it refers.
newmark is an R package for uncertainty analysis in dynamic site and slope
response. The fundamental period of a layered soil column, which describes its
free, undamped horizontal shear vibration on rigid rock, is approximated by the
first Rayleigh iteration in layered form and by a finite element eigenvalue
problem. Uniform hazard spectra are evaluated from seismic hazard curves, which
give the mean annual frequency with which a ground-motion intensity level is
exceeded at a site. The site-response model transforms spectral acceleration at
a reference condition into spectral acceleration at a target site condition
described by VS30, through a random amplification factor that is lognormal at
fixed period, velocities and reference peak ground acceleration. Permanent
seismic displacement measures the accumulated movement of a sliding mass during
an earthquake. For fixed model inputs, rigid-block and flexible-block
regressions represent the positive displacement by a lognormal distribution,
and at a fixed yield coefficient an ensemble pools the realizations of its
models with normalized weights. The yield coefficient kmax for an admissible
displacement Da is the infimum of the positive yield coefficients at which
the probability that the projected, non-increasing displacement curve exceeds
Da is at most a target exceedance probability. A project stores
soil-property summaries, seismic displacement realizations and their
summaries, and yield coefficients associated with admissible displacements in
the tables ShearTable, DnDraws, DnTable and kmaxTable.
The reference, Functions and data, groups the functions by the same families and lists the data sets.
The library and the newmark command are installed together from the
repository root with the product installer.