Performance of Lead Core Rubber Bearing and Viscous Damper in Steel Structures

In recent years, the use of seismic isolators and dampers in protecting important structures against earthquake or explosion loads have increased dramatically. Increase in terrorist attacks have motivated many researchers in studying the effects of explosive load on structures. This paper presents the dynamic response of three structures (i.e., five, ten, and fifteen-story buildings) with fixed base, isolated using lead core rubber bearing and viscous dampers subjected to earthquake and explosion loads. For this purpose, the intended explosion load is considered to be due to the surface explosion of 264 kg of TNT at distances of fifteen and twenty meters from the structure. The pressure load that should be applied to the structures is computed at different points of the considered structures using the AUTODYN software. Finally, the structures are analyzed using SAP 2000 software, and the values of relative displacement, drift ratio, base shear, and plastic joints created in structure's members are computed for all controlled and uncontrolled structures. The results show that relative displacement values in a structure with viscous dampers are significantly reduced (82.7%) for blast loading. Base shear reduces by 40.85% in structures using rubber separator system with lead core rubber bearing system, and it is reduced by 36.19% for structures using the combination of lead core rubber bearing system and viscous damper. The results show that the use of a combined system in the low-rise structures has reduced the structure's drift ratio by 95.17%. For the structures controlled with the viscous dampers, the base shear is increased. This increase was 89.35% for the controlled structure subjected to the blast load at a distance of 20 m from the structure. In contrast, the use of a lead core rubber bearing system resulted in a decrease of 33.19% to 40.84% of the base shear in the controlled structures. The results indicate that the simultaneous use of lead core rubber bearing system and viscous damper improves structure's performance level, and no plastic joints were formed in structures studied. Therefore, according to the above results, it is clear that use of a combined system consisting of lead core rubber bearing system and viscous damper can lead to a safer design of steel structures subjected to the blast load.