Akademik Veri Yönetim Sistemi
STRUCTURES, cilt.82, 2025 (SCI-Expanded, Scopus)
Seismic isolation is widely used to reduce earthquake demands by lengthening the structural period; however, its effectiveness strongly depends on input motions and local soil conditions. This study investigates the influence of site-specific dynamic properties and analysis methodology on the seismic behavior of a four-story reinforced concrete building isolated with lead-rubber bearings. One-dimensional site response analyses were conducted using DEEPSOIL and the site-response toolbox in PLAXIS 2D for two sites representing Soil Classes ZC and ZD. Ground motions were selected from the NGA-West2 database and scaled using both simple amplitude scaling and full-spectrum matching following the Turkish Building Earthquake Code (TBEC-2018) [1]. Analyses were performed with and without groundwater level to evaluate its effect on isolation performance. The results show that local soil conditions and groundwater significantly alter seismic demand. In softer ZD soil, PLAXIS produced shear strains more than twice those in ZC and spectral accelerations roughly 40-70 % higher than DEEPSOIL. Groundwater reduced base displacements in ZD by up to 50 % in DEEPSOIL and 22 % in PLAXIS, whereas reductions in ZC remained below 15 %. Inter-story drift ratios stayed within TBEC-2018 limits, yet PLAXIS predicted 40-50 % larger drifts than DEEPSOIL in ZD. Floor accelerations in ZD increased by about 40 % in PLAXIS relative to DEEPSOIL, while the influence of GWL on acceleration remained below 5 % in ZC. Overall, the findings highlight that reliable seismic isolation design requires explicit consideration of soil class, groundwater level, motion-scaling procedure, and site-response methodology (constitutive soil model and dynamic soil properties), particularly in soft or loose-state soil deposits.