Local site effects on seismic ground response of major cities in UAE

Abstract

This paper investigates the influence of local geotechnical and geological soil conditions on the intensity of ground shaking of major cities in United Arab Emirates (UAE) including Abu Dhabi, Dubai, and Sharjah, and their surrounding areas. Two time histories for each city were chosen based on the target response spectrum that was obtained from results of probabilistic seismic hazard analysis conducted in previous study for UAE. Subsurface geotechnical data from more than hundred different sites were used to evaluate the effect of local site conditions on ground response during earthquake. Dynamic properties of soil for selected soil profiles have been generated, and one-dimensional site response analysis has been conducted. Results are presented in terms of response spectral accelerations (RSA) for different site classes in each city. RSA results indicated that the surficial deposits in the studied areas have the ability to amplify earthquake ground motion significantly with peak amplification at relatively narrow frequency range of 1.5–5 Hz (0.2–0.67-s period). This frequency range was found to be a representative of the predominant frequency ranges of the site classes under consideration. At higher frequencies, slight amplification, and in some cases slight attenuation, is observed. Design response spectra for each site class in each city were developed based on the results of site response analysis. The developed design response spectra were compared with spectrum currently used in each city, and the modified site coefficient is presented.