Simultaneous Evaluation and Comparison of the Performance of Isolator Models in the Soil Structure Interface and Dampers at the Height of Structure under Seismic Load

Seismic isolators and structural control methods, such as the use of dampers, is one of the methods to create safety and relaxation after an earthquake, which has been studied since 1980s. In addition, soil-structure interaction is one of the key parameters in the analysis of structures. In recent decades, the use of seismic isolators and various types of passive control systems has received much attention worldwide. Hence, in this paper, the simultaneous use of LRB isolators in the soil-structure interface and viscous dampers at the height of the structure has been considered under the seismic load. For this purpose, four different types of 5-story steel buildings including moment frame, moment frame with viscous damper, moment frame with base isolator and moment frame with base isolators in the soil structure interface and viscous damper at the height of building were modeled using a software. After the nonlinear time history analysis, results were compared. The average of seven different earthquakes was selected for the purpose of understanding the input ground motion effect. In order to investigate the effect of soil-structure interaction, the 5 story base-isolated moment frame with damper at the height of building was studied with two different modeling approaches: the first one includes raft foundation, soil, and superstructure interaction (SSI model), while the second one considers superstructure based on the fixed base and rigid foundation condition (NSSI model). The results of these isolated moment frame structures with dampers at the height of buildings in the SSI and NSSI models were evaluated. Then the first three mode periods, the peak responses of base acceleration, the peak responses of roof acceleration, the peak responses of story shear, the input energy, the dissipated energy by dampers, the dissipated energy by base isolators, the hysteresis behavior of a damper and an isolator for different models in NSSI and SSI condition were analyzed. The comparison of the results of different NSSI models showed that the simultaneous use of base isolators in the soil structure interface and dampers at the height of moment frame building had a significant effect on structural responses. For example, the peak roof accelerations of base-isolated moment frame with dampers at the height of building were 39 %, 35 %, and 15 % less than the moment frame, the moment frame with dampers at the height of building, and the base-isolated moment frame building, respectively. In addition to the proper performance of isolator dampers, we also achieved the effect of the soil-structure interaction consideration as a key factor in modeling the isolated moment frame structure with dampers at the height of building.