This standard provides guidelines for the analysis, design, and construction of reinforced concrete ring foundations. It is specifically intended for tall, hollow circular structures like chimneys, silos, and towers, detailing methods to calculate stresses, moments, and shear forces resulting from vertical loads and overturning moments.
Code of practice for design and construction of ring foundation
Quick Reference Values
Applicability criteriaGenerally used when ratio of inner to outer radius (a/b) is greater than 0.7
Soil pressure assumptionLinear (trapezoidal) distribution under the ring foundation
Ring beam assumptionThe ring beam is considered rigid
Key Formulas
p(θ) = (P/A) + (M/Z)cos(θ) — Soil pressure at any angle θ
Mθ = M₀ * C1 + M' * C'1 — Bending moment at any angle θ
Tθ = M₀ * C2 + M' * C'2 — Twisting moment at any angle θ
Qθ = (P/R) * C3 + (M'/R) * C'3 — Shear force at any angle θ
Practical Notes
Ring foundations are most efficient for structures with large overturning moments where a central opening is necessary or desirable.
The analysis method is based on the assumption that the ring beam is rigid compared to the soil. This assumption's validity should be checked, especially for large diameter rings on soft soil.
Accurate assessment of soil parameters and soil-structure interaction is critical for an economical and safe design, as the code provides an analytical framework, not soil properties.