The "Structural Engineering Handbook", Gaylord and Gaylord, is a good starting point. The book contains some information regarding the design of silos.
Gaylord and Gaylord also edited a book titled "Design of Steel Bins for Storage of Bulk Solids" - this is an in-depth text on the subject.
Lastly, John Buzek wrote a manual on the design of silos - "Useful Information on the Design of Steel Bins & Silos". It is an AISI publication.