Investigation of earthquake effect of using a seismic isolator in a four story steel structure

In this study, the effects of seismic isolator technique, which is one of the recent earthquake resistant structural design methods, on earthquake loads of steel buildings are discussed. In conventional structural design, the effects of earthquake motion on buildings are compensated by the strength of the structural materials involved. In this context, stresses on structural members, relative storey drifts, rotations about the vertical axis and bending are compared with safety limits. In this approach, all vibrations created by ground motion are transferred to the superstructure through the foundation. However, in the seismic isolation method, special bearings are used between the ground and the structure, which prevent or reduce the transmission of the effects of ground motion to the structure. These bearings are designed to provide sufficient rigidity vertically while having a high displacement capacity horizontally. Thus, it becomes possible for the structure to move horizontally freely and the period of the structure is extended. This period extension reduces the spectral accelerations of the structure. In this study, the effects at the joints of two structures with similar characteristics, one with a seismic foundation isolation system and the other with fixed bearings, are investigated separately.