SCHERR+KLIMKE AG

Cracks in silo walls

1 Constraints for operation during monitoring

2 Schematic isometric view of a silo

3 Top view of an outlet of an upper 4 x ¼ silo

4 Top view of an outlet of a lower cylindrical silo

5 Damages of the silo from outside

6 Wide cracks in the mechanical room at level +32.40 m to +36.50 m

7 Schematic view of cracks in walls and slabs of the silo in the mechanical room at level +32.40 m to +36.50 m and at cross walls of the upper 4 x ¼ silo cells at level +36.50 m to +63.00 m

8 Assumptions for outlet of upper 4 x ¼ silo

9 Horizontal action on silo wall of upper 4 x ¼ silo

10 FE-model of the silo

11 FE-model showing the stresses and deformations due to horizontal pressure in one of the silo cells of the upper 4 x ¼ silo

12 Monitoring devices

13 Measuring data, e.g. stain of reinforcement and filling degree

All Scherr+Klimke AG

The simpler a construction may seem, the more challenging the design can be

All Scherr+Klimke AG

Is it a must to repair and strengthen or even demolish silos if wide cracks are observed? This question might be best answered by means of an example of a reinforced multi-chamber raw meal silo. In this article a special case will be highlighted which may be of interest for many cement producers.

1 Introduction

In general silos are structurally delicate structures. They consist of shell elements and can carry membrane tension or compression forces very well. However any bending moments or shear forces could lead to problems to the structural stability of the silo. In the given case the owner determined several extremely wide cracks in his unconventional multi-chamber raw meal silo during the regular inspection. A first expert opinion came with the result that the silo is under designed and must be strengthened with a heavy steel construction to regain structural stability. As the...