The effect of seismic isolators on the earthquake performance of mid-rise reinforced concrete structures

Turkey is located on the Alpine-Himalayan earthquake zone, one of the most active earthquake zones in the world. With increasing urbanization, the majority of the population lives in cities built on active earthquake faults. The 7.8 and 7.5 magnitude earthquakes centered in Kahramanmaraş, Pazarcık and Elbistan on February 6, 2023 caused significant loss of life and major damage in 10 provinces. In the damage assessment studies conducted after the earthquakes, it was determined that the damage in structures built with tunnel formwork systems was less than the damage in other structural systems. In addition, the importance of using seismic isolators in terms of structural safety in such high-magnitude earthquakes was once again revealed. In this thesis study, the earthquake performance of mid-rise reinforced concrete structures built with tunnel formwork systems and mid-rise reinforced concrete structures built with carcass construction systems (beam floor system and hollow block floor system) were compared depending on the conditions with and without isolators. Finite element models and analyses of the structures were performed with ideCAD software. Earthquake analyses were performed with the Mode Combination Method based on the design spectrum. In order to see the effect of the local soil class on the results, analyses were repeated depending on the five different soil classes included in the Turkish Building Earthquake Code. When the obtained results were examined, it was determined that the earthquake performance of the structures constructed with the tunnel formwork system was better than the structures constructed with reinforced concrete frame construction systems. When evaluated in terms of construction cost, it was seen that beamed floors were more advantageous. It was determined that structural responses were significantly reduced for all soil classes in the case of the use of seismic isolators. In order for seismic isolated structures to show the targeted performance, they should be designed by expert structural engineers, also considering the cost-effectiveness analysis.