A comparison study between 1D and 3D site response analyses based on observed earthquake acceleration records…

Abstract

The characteristics of the site conditions have a very significant influence on the variation of building damage during earthquakes, thus, it is essential to evaluate and analyse the effects of site conditions. One option is to conduct site-specific response analysis to calculate the response of the soil layers by using estimated acceleration records on rock outcrop, shear wave velocity profiles, shear modulus reduction, and damping ratio curves as inputs for the encountered soil layers. The objective of the present work is to evaluate the necessity of 3D site response analysis based on the comparison among the peak ground and spectral accelerations recorded by Istanbul Rapid Response Network and Istanbul vertical array stations during the Mw=6.5 24/05/2014 Gökçeada and Ml=5.7 26/09/2019 Silivri earthquakes with the calculated accelerations by 1D and 3D site response analyses. The shear wave velocity profiles determined based on in-situ geophysical and geotechnical measurements and laboratory tests within the Istanbul Microzonation Project are revaluated adopting an optimization scheme to obtain the best fits between the recorded and calculated accelerations by 1D site response analysis. These modified shear wave velocity profiles are later used for 3D site response analyses performed taking into consideration the three components of the recorded acceleration time histories in all three directions at the bedrock level to model peak ground and spectral accelerations on the ground surface.