Passive and semi-active vibration control of base-isolated structure under blast loading at medium to long distances

With the increasing development of military weapons around the world and the variety of explosives, terrorist attacks are a growing threat. The science of vibration control is well developed against natural loads. Although blast loads are different than natural loads, this science can also be used to reduce explosive load responses. For this purpose, passive and semi-active method included tuned mass damper (TMD) and magneto-rheological (MR) damper have been used to reduce the vibrations caused by the blast load in the base-isolated structure. In this study, a type-2 fuzzy system has been used to determine the appropriate voltage of the MR damper so that the existing uncertainties do not adversely affect its performance. The numerical simulation of two explosives with distance of 15m from a system of 5 degrees of freedom, has been performed by theoretical and empirical equations. The use of the proposed control tools along with the base isolation system showed that not only these methods can maintain the proper performance of the base isolated system, but limit the displacement and possible damages at larger excitations. The comparison results showed that the use of MR damper along with the base isolation system can have the best performance against blast and seismic loads. The use of this system on average reduced the maximum drift of the stories to about 36% in blast loads, 68% in far-field earthquakes and 46% in near-field earthquakes, while the drift of the base significantly has been limited than the base-isolated system with a TMD.