STRUCTURAL DESIGN OF LIQUID MANURE TANKS

Liquid manure is commonly stored in reinforced concrete cylindrical ta nks when land application is not possible. The structural design of li quid manure tanks requires a consideration of ail loads and of appropr iate support conditions. The most important loads for which a cylindri cal liquid manure tank must be designed are reviewed. The selection of an appropriate support condition at the bottom of the tank wall is di scussed. The assumption of a radial spring is recommended for tanks in which floor and wall are not monolithic. The determination of the int ernal hoop forces in the wall of a cylindrical liquid manure tank is d ifficult if the boundary support at the bottom of the wall is other th an sliding or hinged. Design curves are provided to aid designers to d etermine the hoop tension in the wall and in the footing. As well, the radial displacements can be determined using the same design curves. Friction and passive earth pressure can be considered to provide the h orizontal support at the wall footing. The frictional resistance is ea sy to calculate; the passive earth pressure can only be estimated. An example analysis of the hoop tension in a liquid manure tank is provid ed in the Appendix.