IS 11682:1985 is the Indian Standard (BIS) for design and construction of prestressed concrete cylindrical tanks for storage of liquids. This standard provides guidelines for the design and construction of prestressed concrete cylindrical tanks for the storage of liquids. It covers material specifications, design principles for ensuring liquid tightness, analysis of stresses, and construction methodologies including prestressing operations and joint detailing.
Provides recommendations for the design and construction of prestressed concrete cylindrical tanks for liquid storage.
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Design Philosophy for Watertightness | No tensile stress permitted under service loads (Zero Tension). | Tensile stress is permitted, but calculated crack widths must be below a specified limit (e.g., 0.1 mm or 0.2 mm). | ACI 350-20 / EN 1992-3:2006 |
| Minimum Residual Compressive Stress (Circumferential) | 1.0 N/mm² (for tank depth ≤ 6m) or 0.7 N/mm² (for tank depth > 6m). | Not explicitly mandated; performance is governed by crack width limits or limiting tensile stress calculations. | EN 1992-3:2006 |
| Minimum Concrete Cover to Tendons (Liquid Face) | 35 mm. | 50 mm (2 in) for surfaces in contact with liquid. | ACI 350-20 |
| Assumed Total Loss of Prestress (Lump Sum) | 20% for post-tensioning; 30% for pre-tensioning. | Recommends detailed calculation. Lump-sum estimates are typically higher, around 240 MPa (35,000 psi). | ACI 372R-13 |
| Minimum Cast-in-Situ Wall Thickness | 100 mm. | Typically 150-200 mm (6-8 in) to accommodate cover, reinforcement, and prestressing ducts adequately. | ACI 372R-13 |
| Maximum Crack Width Limit | Not specified; cracking is to be prevented entirely. | 0.1 mm (0.004 in) for severe environmental exposure and water tightness. | ACI 350-20 |