Performance of N-Z systems in the mitigation of underground blast induced vibration of structures

Abstract

Control of structural vibration due to wind and earthquake forces has been extensively researched. However, studies on vibration control of structures against underground blasts are limited. It is thereby important to study the usefulness of established vibration control technologies in the blast resistant design of structures. In the present work, an attempt is made to study the effectiveness of the New-Zealand (N-Z) type base isolator (BI) in mitigating structural vibration effects due to blast induced ground motion (BIGM). The BIGM is modeled by an exponentially decaying function representative of a typical rock blast, and the isolator by a bilinear model. The influence of the various BI parameters on its performance is examined in the time domain by considering a single-degree-of-freedom structural model and a realistic five-story building. Numerical studies reveal that the N-Z base isolation system is highly effective in reducing both the underground blast induced structural acceleration as well as the displacement. It is noted that the peak displacement and permanent deformation of the BI may be crucial design criteria. These may, however, be restricted by selecting a proper combination of the BI parameters without significantly compromising the response reductions obtained by it.