Northridge 1D rock/soil Simulation (36 sites) Loma Prieta 1D east/west SAF Simulation (56 sites)
Dec 18, 2015
Kinematic representation of heterogeneous rupture on a finite fault.
- slip amplitude - slip direction (rake) - rupture velocity - rise time
Wave propagation modeled using full waveform Green’s functions calculated for 1D or 3D velocity structure.
Site response based on Vs30 using
Borcherdt’s (1994) short- and mid-period amplification factors.
Deterministic Methodology (f < 1 Hz) Stochastic Methodology (f > 1 Hz)
Limited kinematic representation of heterogeneous rupture on a finite fault (extension of Boore, 1983).
- slip amplitude (stress parameter = 50)
- rupture velocity - rupture duration - average radiation pattern - stochastic phasing
Simplified Green’s functions for 1D
velocity structure. - amplitude decays as inverse of ray
path - impedance effects based on Boore
and Joyner (1997) Site response based on Vs30 using
Borcherdt’s (1994) short- and mid-period amplification factors.
BROADBAND SIMULATION METHODOLOGY:A HYBRID DETERMINISTIC AND STOCHASTIC APPROACH
• Combine using matched filters (1 Hz) and summing in time domain
Tp Tr
A
h
Source Rupture Model
- slip distribution
- rupture timeTi = R / Vr - t (slip) Vr = 0.8 Vs
- slip velocity function
Tr = 2 x 10-9 Mo1/3
Tp = 0.2 Tr
h = 0.2 A
Site Amplification Factors (Borcherdt, 1994)
Fa = (Vref / Vsite) ma (high-frequency) Vref = Vs
30 in simulation
Fv = (Vref / Vsite) mv (mid-frequency) Vsite = Vs
30 at site
Applied in Fourier domain, although strictly defined for response spectra.
Fv
Fa