This standard provides criteria for the structural design of silos, bins, and bunkers used for the storage of granular materials like grain. It details the methods for calculating lateral and vertical pressures exerted by the stored material on the structure's walls and bottom, distinguishing between deep and shallow bins. The code is primarily based on Janssen's and Rankine's theories for pressure calculation.
Lays down general requirements for the design of structures for storage of grains.
Quick Reference Values
Unit weight of Wheat770-850 kg/m³ (Table 1)
Angle of Internal Friction for Wheat25-30 degrees (Table 1)
Coefficient of Friction (μ') for Wheat on Concrete0.40-0.44 (Table 1)
Dynamic factor for wall pressure1.10 (increase of 10% per Clause 3.2.4)
Dynamic factor for hopper loads1.40 (increase of 40% per Clause 3.2.4)
Default Lateral Pressure Ratio (K) basisK = (1-sinφ)/(1+sinφ) (Clause 3.2.3.1)
Key Formulas
ph = (wR/μ') * [1 - exp(-μ'Kh/R)] — Janssen's formula for lateral pressure
K = (1 - sinφ) / (1 + sinφ) — Rankine's formula for lateral pressure ratio
Practical Notes
The code is based on Janssen's theory for static loads. For dynamic effects during emptying, pressures should be increased as per Clause 3.2.4, though modern designs often use more detailed overpressure factors from international codes like Eurocode 1 Part 4.
The choice of material properties from Table 1, especially the angle of internal friction (φ) and wall friction coefficient (μ'), significantly impacts the results. It is crucial to use conservative values appropriate for the specific grain and wall finish.
This code provides the specific loads for bins; the structural design of the concrete elements must be performed in accordance with IS 456.