This code of practice provides guidelines for the cyclone-resistant design and construction of composite structures, including those combining steel, concrete, masonry, and timber. It covers crucial aspects like site selection, structural form, load calculation, and detailing of key elements like roofing and connections. The standard is intended for use in cyclone-prone coastal regions of India to enhance building resilience and safety.
Lays down provisions for the cyclone resistant design and construction of composite structures.
Quick Reference Values
Importance Factor (k4) for cyclone shelters1.30
Minimum roof slope for sheeted roofs1 in 3 (approx 18.5 degrees)
Minimum overlap for asbestos cement sheets150 mm
Minimum end bearing for rafters/trusses on walls100 mm
Minimum recommended thickness of GI sheets for roofing0.63 mm
Key Formulas
Vz = Vb * k1 * k2 * k3 * k4 — Design wind speed calculation (Referenced from IS 875 Part 3)
pz = 0.6 * Vz^2 — Design wind pressure calculation (Referenced from IS 875 Part 3)
Practical Notes
Roofing systems are the most vulnerable component. Special attention must be paid to the anchorage of roofing sheets, using cyclone washers and ensuring sufficient fasteners as per Clause 9.
Connections between different structural elements (e.g., roof truss to wall, wall to foundation) are critical points of failure and must be robustly designed for wind uplift and shear.
Avoid complex building shapes and large overhangs. Simple rectangular or square plans perform better under cyclonic winds as recommended in Clause 7.