DAMPING IDENTIFICATION IN BUILDINGS FROM EARTHQUAKE RECORDS
by Dionisio Bernal, Salma Mozaffari Kojidi, Kenny Kwan and Michael Döhler
Dionisio Bernal, Salma Mozaffari Kojidi, Kenny Kwan and Michael Döhler (2012). DAMPING IDENTIFICATION IN BUILDINGS FROM EARTHQUAKE RECORDS SMIP12 Seminar on Utilization of Strong-Motion Data, p. 39 - 56.
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Seismic response records from the CSMIP database are used to formulate expressions for the expected value of damping ratios as a function of available regressors. The paper discusses the source of the high variance in the identification of damping and proposes mechanisms for the correlation between fundamental building frequency and damping as well as for the observation that damping increases with the mode number. The data analyzed is restricted to cases where the ground accelerations exceed 0.05g and the values obtained, not surprisingly, prove notably larger than those of previous studies, where very small amplitude vibrations were used. Reduced to the most basic observation the results show that the damping ratio of steel buildings (for linear but not ambient level vibration) is typically larger than the widely used 2%, while 5% is reasonable for concrete.