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A replacement for the srss method in seismic analysis
Author(s) -
Wilson E. L.,
Der Kiureghian A.,
Bayo E. P.
Publication year - 1981
Publication title -
earthquake engineering and structural dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.218
H-Index - 127
eISSN - 1096-9845
pISSN - 0098-8847
DOI - 10.1002/eqe.4290090207
Subject(s) - modal , structural engineering , quadratic equation , modal analysis , engineering , computer science , statistics , mathematics , civil engineering , finite element method , geometry , chemistry , polymer chemistry
It is well‐known that the application of the Square‐Root‐of‐Sum‐of‐Squares (SRSS) method in seismic analysis for combining modal maxima can cause significant errors. Nevertheless, this method continues to be used by the profession for significant buildings. The purpose of this note is to present an improved technique to be used in place of the SRSS method in seismic analysis. A Complete Quadratic Combination (CQC) method is proposed which reduces errors in modal combination in all examples studied. The CQC method degenerates into the SRSS method for systems with well‐spaced natural frequencies. Since the CQC method only involves a small increase in numerical effort, it is recommended that the new approach be used as a replacement for the SRSS method in all response spectrum calculations.