Silo Design Codes: Their Limits and Inconsistencies

In order to structurally design a silo, an engineer must determine all loads that are likely to be applied to it. These include, among others, wind, seismic, external, and loads induced by the stored bulk solid. Numerous codes and standards specify means to calculate the latter (so-called solids-induced loads). Among them, the four most common in use in the world today are:
• British Standard BS EN 1991-4:2006 “Eurocode 1 – Actions on structures – Part 4: Silos and Tanks”
• American Concrete Institute ACI 313-97 “Standard practice for design and construction of concrete silos and stacking tubes for storing granular materials”
• American Society of Agricultural Engineers ANSI/ASAE EP433 DEC1988 (R2011) “Loads exerted by free-flowing grain on bins”
• Australian Standard AS 3774-1996 “Loads on bulk solids containers”Unfortunately, guidance to the user is inconsistent between these codes. In addition, many common silo design conditions are not covered by any of them.A brief description of each of these codes, their limitations, and common design conditions that are not covered are identified. Users of silo codes will find this information invaluable, as will code writers who will benefit by being given direction as to how to improve their codes to make them more useful.