Soil height randomness influence on seismic response: Case of an Algiers site

The paper deals with the effect of the depth to bedrock randomness on the seismic response of an Algiers site in time and frequency domains. Stochastic soil profile seismic analysis is carried out via Monte Carlo simulations coupled to the stiffness matrix method. The soil height is assumed to be a random variable with a log-normal distribution. The stochastic behavior of extreme ground acceleration and its response spectrum, transfer function, fundamental frequency, maximum amplitude, short- and mid-period amplification factors are derived from 1000 samples, as a parametric study is performed accounting for the influence of the coefficient of variation of the depth to bedrock. As the study herein considers a SH wave propagation pattern (SH stands for shear horizontal), the accelerations under study correspond to the E–W and N–S horizontal directions. The seismic acceleration corresponds to the Boumerdes earthquake (Algeria, May 21, 2003, M_w = 6.5). The probability density functions of the output parameters are derived using the maximum entropy principle, and compared to the log-normal distribution.The soil height heterogeneity causes an increase in the fundamental frequency of the soil profile, as well as a wider frequency content, in such a way that a larger number of structures are concerned by the resonance phenomenon.