(563d) Effect of Ambient Temperature on Solids Induced Loads on the Walls of Silos

High pressures commonly referred to as overpressures usually occur on silo walls at the commencement of solids discharge. It is understood that the overpressures are not however in themselves necessarily a serious danger to silo structure provided they remain symmetrical. On the contrary, local low pressures (typically asymmetrical loads) can be more damaging than very high but symmetrical pressure. The loss of symmetry may be traced back to in-homogeneity and anisotropy developed in the initial packing during filling. It may also be caused by for instance wind- or thermal- exerted loads externally.

Thermally induced stresses may become critical in cylindrical metal silos. This article reports the results of an experimental investigation into the storage pressure along the walls of a full scale axi-symmetrical silo. The silo was filled with sands, and basked under the Sun. The heating-up is however usually uneven on the walls along circumference because the exposure of silo wall to the Sun is always slant, a characteristic of Scandinavia. Measurement results showed that the pressures measured with transducers varied considerably in response to the thermal variation on the walls. It is suggested that the walls expand or contract, and turned the stored sands in either an active state or a true passive state, to which the walls are in return subjected. As a result, the loads on the wall might increase significantly; the distribution of loads on the walls would be asymmetrical in circumference.