Evaluation of the influence of ground acceleration on the seismic performance of typical RC buildings designed according to the 1975 Turkish Earthquake Code

The ground accelerations recorded during the February 6, 2023, Kahramanmara earthquakes exceeded the design acceleration values specified by the Turkish Earthquake Codes enforced between 1975 and 2018.This paper examines the effect of ground acceleration intensity on the seismic performance of typical RC buildings that are representative of the construction practice governed by the 1975 Earthquake Code and the TS 500 standard.Within this scope, two hypothetical RC frame buildings with equal story numbers and with similar plan areas, assumed to be located in the Hatay-Defne region, were modeled.Both buildings were designed according to the provisions of the 1975 code; however, one building was configured to have a regular and symmetric plan layout, while the other one had a plan and asymmetric stiffness distribution.Equivalent static analyses based on the 1975 code and linear time-history analyses by using the real ground motion records, including the record of the February 6, 2023, Pazarck event, spectrally scaled according to TBEC 2018, were performed.The seismic responses of the buildings were evaluated in terms of floor accelerations, top displacements, base shear forces, and inter-story drifts.In addition, the natural periods and frequency contents obtained by FFT analyses are examined.The results indicate that although increasing ground acceleration significantly amplifies seismic demands in both buildings, the presence of plan irregularity and non-uniform stiffness distribution leads to markedly higher drift and acceleration demands.Consequently, it is concluded that ground acceleration alone cannot explain any probable collapses, and structural configuration and code-based design assumptions play a decisive role in the seismic performance of RC buildings that were designed according to the 1975 Earthquake Code.