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IS 4995:1974 Part 2 is the Indian Standard (BIS) for criteria for design of structures for storage of grains - loads and pressures. This standard provides criteria for the design of reinforced concrete bins used for storing granular and powdery materials. It specifies methods for calculating pressures exerted by the stored material using Janssen's theory and provides characteristic properties for various materials. The standard also covers structural design considerations, referencing IS 456 for concrete design.
Specifies design loads and pressures, including grain pressures, for structures storing grains.
Overview
Status
Current
Usage level
Specialized
Domain
Structural Engineering — Tanks, Silos and Storage Structures
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
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.
Acts as a global guideline specifically for berthing energy and fender design, often referenced by other national standards.
Key Differences
≠Design Philosophy: IS 4995 is based on the Working Stress Method (WSM), allowing increased permissible stresses for certain load combinations. Modern standards like BS 6349 and UFC 4-152-01 are based on Limit State Design (LSD) or Load and Resistance Factor Design (LRFD), using partial safety factors for loads and material strengths.
≠Berthing Energy Calculation: IS 4995 uses a simplified formula and tabular values for berthing velocity. Modern standards (heavily influenced by PIANC) employ more detailed calculations considering hydrodynamic mass, eccentricity, softness of the fender, and provide probabilistic approaches for berthing velocities based on vessel size and exposure conditions.
≠Seismic Design: IS 4995 provides very limited guidance on seismic design, primarily referencing IS 1893 and using a basic seismic coefficient method. In contrast, standards like UFC 4-152-01 and ASCE/COPRI 61-14 provide extensive, performance-based seismic design criteria, including detailed soil-structure interaction and liquefaction analysis.
≠Mooring Load Calculation: IS 4995 provides empirical values for bollard capacities based on vessel DWT. Modern codes like BS 6349 require a more rigorous calculation of mooring forces based on wind and current action on the moored ship, often recommending dynamic analysis for exposed locations.
Key Similarities
≈Load Categories: All standards consider the same fundamental types of loads on berthing structures, including dead loads, live loads (surcharge), berthing forces, mooring forces, and environmental loads like wind, current, and seismic forces.
≈Consideration of Berthing Energy: All codes recognize that the kinetic energy of the berthing vessel is the primary design consideration for the fender system and for determining the impact load on the main structure.
≈Structural Forms: The basic types of berthing structures addressed (e.g., open piled jetties, monolithic gravity caissons, sheet pile walls) are common across all the standards.
≈Operational Loads: All standards include provisions for operational loads such as surcharge from cargo and vehicles, crane loads, and forces from mooring equipment like bollards and capstans.
Parameter Comparison
Parameter
IS Value
International
Source
Design Philosophy
Working Stress Method (WSM)
Limit State Design (LSD) / Load and Resistance Factor Design (LRFD)
BS 6349-2:2010
Live Load / Surcharge (General Cargo)
1.0 t/m² (approx. 10 kN/m²)
Typically 20-30 kN/m² (e.g., 25 kN/m² is common)
BS 6349-2:2010
Berthing Velocity (Example: 50,000 DWT, normal conditions)
15-25 cm/s, based on exposure (Table 1)
Calculated based on charts/formulas considering tug assistance and approach angle; typically 12-18 cm/s.
PIANC Guidelines
Hydrodynamic Mass Coefficient (Cm)
Cm = 1 + 2T/B (where T=draft, B=beam)
Formula-based (e.g., Vasco Costa's) or recommended values, typically between 1.4 and 1.8 depending on under-keel clearance.
BS 6349-2:2010
Bollard Capacity (Example: 60,000 DWT vessel)
100 tonnes (from Table 2)
Derived from calculated wind/current loads; typically in the range of 100-150 tonnes.
UFC 4-152-01
Load Combination with Berthing Load (Accidental)
Permissible stresses may be increased by 25% (WSM)
Load factor on accidental berthing action is 1.0 at Ultimate Limit State (ULS)
BS 6349-2:2010
⚠ Verify details from original standards before use
Key Values6
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
Tables & Referenced Sections
Key Tables
Table 1 - Physical Properties of Granular and Powdery Materials
How do I calculate the pressure from grain in a silo?+
Use Janssen's formula given in Clause 3.2.1, which requires the material's unit weight, angle of friction, and wall friction coefficient from Table 1.
What is the formula for the lateral pressure ratio 'K'?+
The code specifies using K = (1 - sin φ) / (1 + sin φ), where φ is the angle of internal friction of the stored material (Clause 3.2.3.1).
Do I need to increase loads for dynamic effects like emptying?+
Yes, Clause 3.2.4 requires increasing calculated wall pressures by 10% and loads on hopper bottoms by 40% to account for dynamic effects.
Where can I find the properties for stored materials like cement or wheat?+
Table 1 provides physical properties like unit weight, angle of internal friction, and coefficient of friction for various common granular and powdery materials.