Düşey deprem bileşenlerinin deprem yalıtımlı binaların izolasyon yer değiştirme tepkisi üzerindeki etkisi

4 th International Civil Engineering & Architecture Conference, Trabzon, Türkiye, 15 - 19 Mayıs 2025, cilt.1, ss.171-180, (Tam Metin Bildiri)

Seismic isolation is a widely implemented strategy for mitigating earthquake-induced demands on

structures by incorporating isolator units at the foundation or other appropriate substructure levels. This approach

effectively lengthens the natural period of the structure through horizontally flexible isolation elements, allowing

the superstructure to respond in a near-rigid-body manner relative to the ground. As a result, interstory drift ratios

and floor accelerations are significantly reduced, thereby preserving structural integrity and minimizing damage

to non-structural components. Nevertheless, the performance of seismic isolation systems can be adversely

affected under near-fault ground motions, which are characterized by high-amplitude velocity pulses and

significant vertical ground motion components. These characteristics can notably increase seismic demands on the

isolation system, necessitating a detailed evaluation of their effects. Prior studies have emphasized the critical role

of such components in the seismic behavior of base-isolated structures. In this study, three-story and six-story

three-dimensional reinforced concrete moment-resisting frame structures equipped with lead-rubber bearings

(LRBs) were modeled using SAP2000. Two pulse-like ground motion records containing both horizontal and

vertical components were selected in accordance with the Turkish Building Earthquake Code (TBEC-2018) and

scaled to match the target design spectra for the relevant site classes. Nonlinear time history analyses were

conducted under two excitation scenarios: (i) horizontal components only, and (ii) combined horizontal and

vertical components. The seismic response was assessed with particular focus on isolator performance, specifically

evaluating both horizontal and vertical displacement demands of the isolation units. The findings indicate that the

inclusion of the vertical ground motion component increased vertical displacement demands under compressive

effects in all isolators of the three-story building, while in the six-story building, it slightly reduced the

displacement demands in isolators subjected to tensile effects and slightly increased those in isolators under

compressive effects.