The Earthquake Engineering Online Archive

Probabilistic study of the behavior of structures during earthquakes

Ruiz, Patricio T.; Penzien, Joseph

UCB/EERC-69/03, Earthquake Engineering Research Center, University of California, Berkeley, 1969-03, 92 pages (531/R83/1969)

Records of strong-motion earthquakes are simulated using filtered shot noise. Twenty sample records are then used to simulate the response of a structure subjected to earthquake excitation. Monte Carlo computations of the response are performed to obtain the information required to predict future response at various reliability levels. A linear stochastic model is utilized to generate records of a filtered shot noise used to simulate accelerograms recorded during strong-motion earthquakes. A method is developed to design the stochastic model in such a way that it will reflect the principal features that are to be simulated. This is done using a sample of records of real earthquakes of the characteristics expected from the random process. A family of 20 artificial acclerograms of 30 sec duration and expected maximum acceleration of 30 percent g is generated to simulate the effect of strong-motion earthquakes of a magnitude of about 8.3 on the Richter scale and recorded on firm soil at an epicentral distance of about 45 miles. The average pseudo-velocity spectra are computed for the ensemble of artificial records and good agreement is found with the smooth standard spectra for a spectral intensity of 3.6. The response of idealized multistory structures when subjected to strong-motion earthquakes is investigated using the ensemble of 20 artificially generated accelerograms as excitation. A dynamic analysis is performed to study the response of an 8-story shear-type building subjected to this family of artificial earthquake records. Inelastic behavior of the structure is considered (1) by introducing the same fraction of critical viscous damping in all modes of elastic vibration and (2) by assuming a bilinear hysteretic type of force-deflection relationship between the story shear and the relative story. Material properties are chosen so as to simulate the behavior of realistic structural systems. Four structural cases are analyzed including rigid and flexible structures for two values of viscous damping.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-69-03.pdf (3 MB)