by E. Miranda and V. Bertero
Miranda, E., and V. Bertero (1991). Evaluation of Structural Response Factors Using Ground Motions Recorded During the Loma Prieta Earthquake. SMIP91
Seminar on Seismological and Engineering Implications of Recent Strong-Motion Data, p. 4-1 - 4-10.
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Present procedures of defining seismic design forces are based on the use of
elastic spectra reduced by a response modification factor which only depends
on the type of structural system. This paper summarizes the results of an
analytical study concerning strength reduction factors. Strength demand and
strength reduction spectra were computed using simplified elastic and inelastic
bilinear SDOF structural models and 36 ground motions recorded during the
1989 Loma Prieta earthquake. Special emphasis was given to the influence of
local site conditions. Results show that strength reduction factors are significantly
affected by the level of inelastic deformation, the period of vibration and
by local site conditions.