• Structural Engineering and Mechanics
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• v.16 no.6
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• pp.675-693
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• 2003

In order to consider the modified seismic response of framed structures in the presence of masonry infills, proper models have to be formulated. Because of the complexity of the problem, a careful definition of a diagonal pin-jointed strut, able to represent the horizontal force-interstorey displacement cyclic law of the actual infill, may be a solution. In this connection the present paper shows a generalized criterion for the determination of the ideal cross-section of the strut mentioned before. The procedure is based on the equivalence between the lateral stiffness of the actual infilled frame scheme during the conventional elastic stage of the response and the lateral stiffness of the same frame stiffened by a strut at the same stage. Unlike the usual empirical approaches available in the literature, the proposed technique involves the axial stiffness of the columns of the frame more than their flexural stiffness. Further, the influence of the bidimensional behaviour of the infill is stressed and, consequently, the dependence of the dimensions of the equivalent pin-jointed strut on the Poisson ratio of the material constituting the infill is also shown. The proposed approach is extended to the case of infills with openings, which is very common in practical applications.

• Bulletin of the Korean Space Science Society
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• 2005.04a
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• pp.138-142
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• 2005

A reaction wheel, an actuator for satellite attitude control, produces disturbance torque and force as well as its axial control torque. The disturbances have an influence on the pointing stability of high precision satellites. The measurement of disturbances for such a satellite, therefore, is necessary. The wheel's rotation, however, causes the vibration of the table and its vibration induces measurement errors, especially large near the resonance frequency of the Measurement table. For the purpose of overcoming these defects, a calibration method using frequency compensation is suggested in this paper. Disturbance parameters are identified from data examined by frequency compensation. Measurement frequency range can be expanded far higher than the resonance frequency, since the degradation of data accuracy caused by its vibration is well alleviated even in the resonance area.