Earthquakes frequently cause damage or collapse in silos, provoking significant financial loss and even loss of life. The effect of lateral seismic loads can damage the upper portion of the silo if the material contained can oscillate inside the silo during the ground motion. The contribution of the grain sliding in terms of wall stresses is not explicitly accounted neither in current design codes nor in scientific literature. In the present paper, the effect of the horizontal sliding of the grain layers is accounted in terms of additional overpressures, wall shear and bending moment during dynamic excitation and compared with theoretical formulations, code provisions and experimental evidence. Shaking table tests suggest that the grain sliding may be relevant in the evaluation of the wall base bending moment and that ACI 313-97 and Eurocode 8 provisions appear overly conservative. Finally, a design recommendation is drawn for reducing the effect of the seismic actions on the silo wall.
Full Text (PDF)