What Is EZ-FRISK™?
What Can It Do for You?
Technical Capabilities
Purchasing EZ-FRISK™
Register Now!

Technical Capabilities

Spectral Matching

The Spectral Matching module creates high-quality design ground motion time histories by taking actual earthquake accelerograms and adjusting them to match a target response spectrum. These time histories are used by structural engineers in non-linear analyses of the dynamic response of buildings and soil structures to earthquake ground shaking.

The ground motion time histories used in structural analyses need to accurately reflect a design level of safety and have realistic time-dependent characteristics. This requirement can be met by:

EZ-FRISK™ gives you the tools to get this job done. It provides Norm Abrahamson’s time-dependent spectral matching method — RSPMATCH — with an integrated, interactive, visual user interface.

Target Response Spectrum

With EZ-FRISK™, you can provide a user-defined target spectrum or match to a uniform hazard spectrum from a probabilistic seismic hazard analysis.

By matching to uniform hazard spectrum, the design ground motion will consider the likelihood of earthquakes occurring at all surrounding faults, as well as the ground motion arising at a site from earthquakes of various magnitudes and distances. With EZ-FRISK™, you can directly enter the design return period.

Input Accelerogram Choice

Real earthquake ground motions have complex time-dependent behavior that is influenced by the magnitude of the earthquake and the distance between the earthquake epicenter and a site. With EZ-FRISK™, you can identify one or several combinations of magnitude and distance that characterize the seismic hazard of a site by using seismic hazard analysis to deaggregate the hazard by earthquake magnitude and distance.

EZ-FRISK™ provides a very useful tool that allows you to search through the more than ten thousand records in the PEER NGA strong motion database in just a few minutes according to user-defined filters and criteria. You can filter out records based more than one hundered record attributes as defined in the PEER NGA flatfile such as:

It displays the accepted accelerograms, with thumbnail previews of the time histories and response spectra, sorted by the weighted criteria. The following criteria can be weighted by the user:
Can select any number of records to match, and they will be downloaded from the PEER web site for use with EZ-FRISK. This feature can save you hours in selecting good initial accelerograms.

You can also search through records from the U.S. Nuclear Regulatory Commission Western United States Time History Data Base and the Central and Eastern United States Time History Data Base.

Spectral Matching Algorithm

EZ-FRISK™ now features the 2009 version of RSPMATCH as documented in:

"An Improved Method for Nonstationary Spectral Matching", Linda Al Atik and Norman Ambrahamson, Earthquake Spectra, Volume 26, No. 3, pages 601-617, August 2010

RSPMATCH is widely considered to be the best method to create realistic ground motions, far better than methods that operate in the frequency domain. The core code has been enhanced with additional capabilities and improved flexibility.

Spectrally matched ground motion time histories for bedrock should be further processed to incorporate the site response, which is the modification of the time history caused by the unique layering of rock and soil at the site. EZ-FRISK™ now includes Site Response Analysis using SHAKE91. SHAKE91 propagates the bedrock time history through soil and rock layering to produce a site-specific outcropping ground motion. With EZ-FRISK™, you can quickly process a suite of matched accelerograms.