Earthquake-proof of Concrete Stave Silos with Structural Discontinuity

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Concrete stave silos are segmental silo structures which are cylindrically assembled from precast concrete blocks called "staves" and held together by exterior adjustable steel hoops.A series of shaking table tests was performed using a 1/8- scale stave sile model and a cylindrical shell model. The effects of the joints of staves and of a stored material on the dynamic behavior are also investigated. The experimental results reveal that the hysteretic restoring force characteristics of concrete stave silos are caused by not only the damping effect of a stored material but also their structural discontinuity.For dynamic analysis of concrete stave silos with such structural discontinuity, a new discrete model called "stave silo element" is developed. A method for determining spring stiffness in stave silo elements is also proposed : at first, the equivalent spring stiffness to the continuous cylindrical shell are calculated and then a reduction factor of the equivalent stiffness is estimated. To verify the validity of stave silo elements and the method of the equivalent stiffness and its reduction factor, seismic response analyses of a stave silo model are carried out and compared with its experimental results. A good agreement was obtained.