American Society of Civil Engineers

Seismic Response Modification Factors

by Andrew Whittaker, M.ASCE, (Assoc. Dir., Earthquake Engrg. Res. Ctr., Univ. of California at Berkeley, 1301 South 46th St., Richmond, CA 94720), Gary Hart, M.ASCE, (Prof., Univ. of California at Los Angeles, Boelter Hall, Los Angeles, CA 90024), and Christopher Rojahn, M.ASCE, (Executive Dir., Appl. Tech. Council, Redwood City, CA 94065)

Journal of Structural Engineering, Vol. 125, No. 4, April 1999, pp. 438-444, (doi:

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Document type: Journal Paper
Abstract: The response modification factor plays a key role in the seismic design of new buildings in the United States. To date, the values assigned to this factor are based on engineering judgment and have little sound technical basis. Any improvement in the reliability of modern earthquake-resistant buildings in the United States will require the systematic evaluation of the building response characteristics that most affect the values assigned to the factor. To this end, a draft formulation that represents the response modification factor as the product of factors related to reserve strength, ductility, and redundancy is presented in the paper. Pertinent data from various analytical and experimental studies on reserve strength and ductility are also presented.

ASCE Subject Headings:
Earthquake resistant structures
Seismic design
Structural response