University of California at Berkeley
Civil and Environmental Engineering
Instructor: Stephen A. Mahin
Spring Semester 2005
CEE 227  Earthquake Resistant Design
Problem 8  Simplified Probabilistic Site Hazard Analysis
In the last problem, we are able to get an idea of the worst earthquake ground shaking
that can occur at a site. This is quite useful, especially for risk adverse clients as well as
for critical or hazardous facilities. It is also essential for calculation of a deterministic
estimate of shaking from a characteristic earthquake on a nearby fault.
However, for
normal circumstances, and for parts of the country where the seismicity is lower than
California, the likelihood of a worstcase earthquake is very small during the life of the
structure. In such cases, a probabilistic hazard analysis is appropriate.
Such analyses are
more complex and require much more information to be able to properly judge
uncertainties in the length of rupture, location of the hypocenter, direction of rupture and
so on.
The US Geological Survey has done a probabilistic hazard analysis for the entire
U.S.
This is done based on zip codes, so it may not be sufficiently accurate for certain
locations (nearfault locations, rapidly changing soil conditions, etc.). However, it is the
basis for new guidelines and codes such as FEMA 273/356, FEMA 350352, FEMA 365
and IBC 2000.
In this problem, we will construct an elastic response spectrum for 5% viscous damping
corresponding to this probabilistic hazard map.
a.
Log on to: http://earthquake.usgs.gov/research/hazmaps/.
There are various options,
but for the most part we will use the “Seismic Design Values for Buildings” section.
A separate note will be distributed to help you use this site (finding latitudes and
longitudes, which maps to look at, etc.). Assume that the address of the building is
2108 Shattuck Avenue, Berkeley, CA.
Find the estimated peak ground acceleration
at the site for 10%, 5% and 2% probabilities of exceedence in 50 years.
a.
From the USGS site, find the PseudoSpectral Acceleration for our address
corresponding to these three probability levels for 0.2 and 1 second periods.
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 Spring '06
 Mahin
 USGS, Earthquake engineering, elastic response spectrum, Newmark and Hall

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