Research Information System
1. International Ankara Scientific Research Congress, Ankara, Turkey, 21 - 22 December 2024, pp.277-285
In this study, the site
response analysis approach was used to determine earthquake-induced forces that
could potentially damage structures. The study is based on modeling the
propagation of seismic waves, generated by fault ruptures at the earthquake
source, through the subsurface to the top of the bedrock beneath a given area.
In order to determine the amplification function of the soil layer above the
bedrock from the modeled seismic waves, the transfer functions for two
locations in the Beyoğlu and Küçükçekmece districts were
calculated. For this purpose, the soil profiles from drillings and the
acceleration records were used from the Beşiktaş 3407 station during the Mw=5.8
earthquake that occurred on September 26, 2019, off the coast of Silivri in the
Marmara Sea near Istanbul. The calculations employed one-dimensional models
with an assumption of non-damping soil. The impact of soil layer thickness and
Vs30 velocity on the transfer function was analyzed. Variations in ground
transfer functions as a function of soil parameters were illustrated by
altering the depth of the bedrock and the Vs30 velocity. For Küçükçekmece, when
comparing the acceleration spectrum recorded on the bedrock with the amplitude
spectrum of the surface output motion, the maximum acceleration was calculated
to increase from 0.6 g to 2 g. According to the transfer function, the highest
amplification was approximately 3.5. When the Vs30 velocity of the soil layer
over the bedrock was reduced, the highest amplification in the transfer
function rose to around 6.0. For the soil profiles in the Beyoğlu district, the
maximum acceleration was calculated to increase from 0.6 g to 1.5 g. When the
bedrock depth at this station was further increased, an increase in ground
amplification was observed. This result indicates that as the thickness of the
soil layer increases, the ground amplification value also increases, and the
amplification particularly becomes more pronounced at higher frequencies.
Keywords: Transfer function, 1D model, soil amplification