Abstract-This paper deals with an application of H∞ control attenuating initial-state uncertainties to the magnetic bearing and examines the H∞ control problem, which treats a mixed Disturbance and an Initial-state uncertainty Attenuation(DIA) control. The mixed H∞ DIA problem supplies H∞ controls with good transients and assures H∞ controls of robustness against initial-state uncertainty. On the other hand, active magnetic bearings allow contract-free suspension of rotors and they are used for various industrial purposes. We derive a mathematical model of the magnetic bearing which has complicated rotor dynamics and nonlinear magnetic property. Then we apply this proposed H∞DIA control for the magnetic bearing, and design a robust H∞ controller both for exogenous disturbances and for initial state uncertainties of the plant. Experimental results show that the proposed robust control approach is effective for improving transient response and robust performance.
Mixed structures composed of reinforced concrete columns and steel beams can realize larger building spaces, whereas reinforced concrete columns are subjected to thermal stresses due to thermal elongation of long span steel beams in case of fire. It is very important to clarify the load carrying capacity of the complicated beam-column connections in fire. This paper presents the results of the sub-frame fire tests of a mixed structure composed of up-and-down RC column, steel beam and the connection. The test results indicate the non-fire-protected connection covered with thin steel plate has load carrying capacity during 3 hours of standard fire temperature curve. In this paper, fire performance of the beam-column connections is discussed.
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