S. Yang, L. Li, Z. Li, M. Zheng, and G. Song (PR China)
Smart isolation system, MR damper, semi-active control, soil-structure interaction, and aqueduct.
The superstructure of massive flow aqueducts have much more mass than that of ordinary road (or railway) bridges. Seismic isolation bearings are often employed in order to reduce the large inertial forces of the superstructure during an earthquake. However, the displacement of the seismic isolation bearing, usually larger than that of the ordinary bridge bearing, may be excessive and damage nearby water seal glands. Therefore, it is necessary to utilize a combination of Magnetorheological (MR) dampers and seismic isolation bearings to further reduce the displacement. This paper presents a model of an aqueduct fitted with a smart isolation device. In the model, one span aqueduct was considered and the behaviour of the pier was assumed to be linear. The foundation system was modeled as a combination of frequency-independent springs and dashpots, and the control strategy employed was clipped optimal control. Time history analyses were carried out. Numerical analyses showed that the smart isolation system can effectively reduce responses of the aqueduct and keep displacement of the bearing within limits. Meanwhile, the effect of soil structure interaction (SSI) on the response of the aqueduct was considered, and it was found that the effectiveness of the control may be overestimated if SSI is not regarded.
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