Summary The goal of probabilistic seismic hazard analysis (PSHA) is to quantify the rate (or probability) of exceeding various ground-motion levels at a site (or a map of sites) given all possible earthquakes. The numerical/analytical approach to PSHA was first formalized by Cornell (1968). The most comprehensive treatment to date is the SSHAC (1997) report, which covers ... many important procedural issues that will not be discussed here (such as the use of "expert opinion", the meaning of "consensus", and how to document results). Except where otherwise noted, the SSHAC report represents a good source of additional information. It's a must-read for anyone conducting PSHA.
Traditionally, peak acceleration (PGA) has been used to quantify ground motion in PSHA (it's used to define lateral forces and shear stresses in the equivalent-static-force procedures of some building codes, and in liquefaction analyses). Today the preferred parameter is Response Spectral Acceleration (SA), which gives the maximum acceleration experienced by a damped, single-degree-of-freedom oscillator (a crude representation of building response). The oscillator period is chosen in accordance with the natural period of the structure (roughly number_of_stories/10), and damping values are typically set at 5% of critical.
To keep things simple, PGA will be used as the ground-motion parameter here (the analysis is otherwise equivalent).
PSHA involves three steps:
1) specification of the seismic-hazard source model(s);
2) specification of the ground motion model(s) (attenuation relationship(s));
Name:
EDWARD (NED)
H.
FIELD
Phone:
626-583-7814
Fax:
626-583-7827
Email:
field at usgs.gov
Contact Address:
USGS
Geology Division
525 South Wilson Ave. City:
Pasadena
Province or State:
CA
Postal Code:
91106-3212
Country:
USA
Personnel
TYLER
B.
STEVENS Role:
SERF AUTHOR
Phone:
(301) 614-6898
Fax:
301-614-5268
Email:
Tyler.B.Stevens at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Global Change Master Directory City:
Greenbelt
Province or State:
MD
Postal Code:
20771
Country:
USA
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