Behaviour of empty steel grain silos under wind loading: part 2: the stiffened conical roof shell

Abstract

This paper presents the second part of the results of detailed finite element analyses of three empty stiffened steel grain silos under nonuniform wind loading. In the present paper (part 2), the behaviour of the roof system is discussed, while in part 1, the behaviour of the stiffened silo wall was presented. The behaviour of the three silos analysed (tall, intermediate and shallow), depends on the geometry and the stiffening of the silo. The roof of the tall silo, reinforced with radial ribs only, develops stress resultants predominantly in the radial direction and transfers them to the centre collar and the wall in one-way bending. The roof systems of the larger diameter intermediate and shallow silos are reinforced with stiffeners and exhibit much more complicated behaviour. The stiffened roof shells of these latter two silos behave as continuous one-way slabs acting compositely with the rafters, with the purlins providing elastic support.