Stochastically based review of site-dependent response spectra parameters adopted in the seismic design code of Albania

Taking advantage of a large soil data base established during the microzoning studies recently carried out for five largest urban areas of Albania, an attempt has been made to review the site-dependent response spectra parameters adopted in the current Albanian seismic design code (KTP-N.2-89), providing thus a basis for its harmonization with Eurocode 8. In absence of recorded strong ground motions at various intensity levels required for a proper earthquake resistant design, a theoretical earthquake input motion description is conceived and on this basis a stochastic model for predicting site-dependent response estimates, in an approximate but acceptable form for practical design purposes, is formulated. Using this model, 110 soil profiles, categorized in three subsoil classes (A, B, C) according to Eurocode 8, were analyzed generating thus for each subsoil class the mean spectra and its standard deviation and coefficient of variation. Results presented in this study indicate that site-dependent response spectra approach of Eurocode 8 could represent the site-effects in a more realistic manner than that one currently in use in the seismic design practice of Albania.