In recent years, the use of seismic isolation has become a very useful way to protect buildings against earthquakes, especially in the developed world. Considering the importance of maintaining the performance of buildings and protecting what is inside the buildings, many buildings are built with seismic isolation. Depending on the geometric shape and type of building use, for some buildings, separation of the middle story can be more efficient than the usual isolation technique. In this paper, the behavior of moment resisting frame steel structures with moment resisting frame systems has been investigated using a middle story isolation system and compared with two methods without isolation and with base isolation.
In this study, nonlinear time history analysis was used and the behavior of structures under near field earthquake cases was investigated. The results show that the isolation of the middle story can have a positive effect on the seismic behavior of the moment resisting frame steel structures.