IS 3370 Part 3 lays down the code of practice for the design and construction of prestressed concrete liquid storage structures, focusing on crack control and liquid-tightness. It prescribes permissible stresses, detailing, and prestressing requirements to ensure zero tension at liquid-contact faces.
Provides requirements for the design and construction of prestressed concrete structures for storage of liquids.
Quick Reference Values
minimum concrete grade post tensionedM 30
minimum concrete grade pre tensionedM 40
max compressive stress at transfer0.5 fck
minimum clear cover prestressing steel35 mm
allowable tensile stress liquid face0 MPa (No tension condition)
Key Formulas
f = P/A ± Pe/Z ± M/Z — Resultant stress at any section under working load
Practical Notes
Ensure zero tensile stress at liquid-retaining faces under service loads to prevent leakage.
Proper sequence of circumferential and vertical prestressing is critical for cylindrical tanks to avoid cracking during transfer.
Account for loss of prestress due to shrinkage, creep, and friction as per IS 1343.