Depth to bedrock randomness effect on design spectra in the city of Algiers (Algeria)

The paper deals with the sensitivity of the structural response at the Dar El Beida site in the city of Algiers (Algeria) to the randomness of the depth to bedrock. Several typical reinforced concrete buildings, erected on a multilayered soil, are analyzed under seismic inputs under the hypotheses that the soil thickness (i.e., depth to bedrock) and the shear wave velocity are lognormal random variables. The sensitivity analysis relies on the stiffness matrix method combined with Monte Carlo simulations. The results show that the response spectra, for fundamental periods, and the frequency content are very sensitive to the depth to bedrock randomness.The base shear as well as the interstory drifts and lateral displacement of the buildings are also influenced by this randomness. Furthermore, these parameters (base shear, interstory drift and lateral displacement) are compared to the results given by three seismic codes, i.e., UBC97, EC8 and RPA99 (Algerian seismic code).