Considering Uncertainty in Earthquake Response Spectra
 

Sara Wadia-Fascetti
    Assistant Professor, Northeastern University

Burcu Gunes
    Graduate Student, Northeastern University
 

ABSTRACT

Structural response is dependent both on the structural system and the forces applied to the structure; and its evaluation requires an analytical structural model as well as an estimate of the loads acting on the structure.  The applied load to the structure is the time history created by the earthquake and it is impossible to predict due to the random nature of earthquake ground motions.  The ultimate error in the structural response is due to the approximations inherent in the models used to predict dynamic characteristics and the excitation acting on the structure.  An inaccurate or simplified analytical model inherently contains uncertainties which are passed onto the predicted response.  Additionally, the unavoidable fact exists that it is nearly impossible to predict what kinds of loads the structure will be subjected to.  As a result, design spectra are used to provide seismic forces which the structure is required to resist.

The purpose of this study is to investigate and propose methods to incorporate uncertainty into the analytical representation of the earthquake ground motion.  Two specific objectives are:  (1) to propose uncertainty models used in response spectra development; and (2) to study the influence of these models on structural response.  The uncertain parameters considered in this study are distance to the rupture zone and soil properties for different earthquakes.
 

Contact Information:

Prof. S. Wadia-Fascetti (swf@neu.edu)
Dept. of Civil & Env. Engineering
Northeastern University
Boston, MA  02115

Reference:

Wadia-Fascetti, S., and Gunes†, B. V., (1996) “Considering Uncertainty in Earthquake Response Spectra.”  ASCE Specialty Conference: Natural Disaster Reduction.  December 1996.  pp.  211-212.

 
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