Whenever an engineer sits down to design an underground precast concrete structure, buoyancy is one of the critical factors that should be considered in the plan. The sheer weight of concrete and steel structures of this type offers one of the main advantages of precast over lighter materials. But even though we know that a precast structure will sit down firmly in the excavation, buoyancy must still be considered in the design process.
Factoring in the buoyancy of your product is critical to prevent the structure from floating or shifting upward. To help precasters better understand buoyancy and make these calculations, NPCA developed a Buoyancy White Paper several years ago that outlines the process in detail. That white paper has now been updated and enhanced to include sample calculations, extensive definitions of terms and clarification of equations throughout the paper.
For example, all the terms are now shown in bold in the examples, and the equations have been numbered under each section. Figures have also been recalculated to clarify each concept and example. Other formatting changes and rewritten equations better clarify the concepts outlined in the white paper.
The NPCA Buoyancy White Paper is also supplemented by a buoyancy calculator for both rectangular and round structures. This calculator is Excel-based and provides easy-to-use calculation menus for both rectangular and round structures.
If you have any questions, please contact Phil Cutler at [email protected] or (800) 366-7731.