Reduction Measure for 3-D structure During Near-Source Ground Motions

Abstract

In this study an approach for reducing the influence of the strong long-period pulses as well as the effect of the simultaneous ground excitation on a three-dimensional (3D) frame structure is presented. The considered ground excitation is the 1995 Kobe earthquake and the 1999 Turkey earthquake. The investigation reveals that the common base isolators are not reducing the response of the structure in the case of the near-source earthquakes with long period impulses. Even they can amplify the response of the structure. By modifying the fundamental natural mode of the structure, we can reduce the effect of the strong pulses of the horizontal ground motion. The improvement of the dynamics of the structure is achieved with the combination of the lateral elastic spring and the viscous damper at the first story level of the structure and the base isolation. The proposed approach reduces not only the displacement but also the activated forces in the structural members.