This standard lays down the criteria for the structural analysis, design, and detailing of reinforced concrete shell structures (cylindrical, spherical, conoidal, etc.) and folded plates. It provides guidelines on minimum thickness, reinforcement limits, and buckling considerations to ensure stability and structural integrity of these complex roof forms.
Criteria for design of reinforced concrete shell structures and folded plates
Quick Reference Values
minimum thickness cast in situ50 mm
minimum thickness precast25 mm
maximum reinforcement spacing3 times shell thickness or 300 mm (whichever is less)
minimum reinforcement area0.15% of gross cross-sectional area in principal directions
minimum clear cover15 mm or diameter of bar (whichever is greater)
Practical Notes
Buckling checks are critical for large-span or very thin shells, as geometric instability often governs the design before material failure.
Special attention must be given to reinforcement detailing at the junctions of shells with edge beams or traverses due to high localized bending moments and shear stresses.
Temperature and shrinkage effects must be carefully analyzed, and adequate reinforcement should be provided to control cracking, especially in continuous or large shells.