Abstract
Shear modulus plays a fundamental role in the estimation of the ground response parameters in seismic microzonation studies. A large number of site response studies are still being carried out using SPT data, considering existing correlations between SPT N-values and shear modulus without knowing the effectiveness of the shear modulus correlation for the type of soil column. To the best of our knowledge, there is no clear-cut guideline regarding the use of a suitable shear modulus correlation to estimate representative shear stiffness for a specific soil column in response studies. In this study, therefore, an attempt has been made to identify a suitable correlation for estimating shear modulus (G(max)) for different types of soils, such as sand, clay and gravel or a mixture of all three. Sites with earthquake data recorded at the surface (soil profiles along with SPT N-values and shear wave velocity), are selected from the K-NET (Japanese website) data set. The collected earthquake data consists of moment magnitudes (Mw) ranging from 5.0 to 9.0, which were recorded at different epicentral distances. Nonlinear site response studies have been carried out by considering earthquake data recorded at a rock site as an input ground motion to the soil profiles, as published in the K-NET data site. Surface ground motion and response spectrums were further obtained from different G(max) correlations and were compared with surface recorded time histories for the same event. This study shows that peak ground acceleration (PGA), response spectrums (RS) and amplification factors (AF) obtained from a very few G(max) correlations are comparable with the recorded PGA, response spectrum and amplification factor.