Handbook›Basic Wind Speed by City (IS 875-3)

Basic Wind Speed by City (IS 875-3)

IS 875 (Part 3) : 2015 · Clause 5.2 — Basic Wind Speed & Figure 1 (Wind Zone Map)
Basic wind speed (Vb) for structural design as per IS 875 Part 3. Design wind speed Vz = Vb × k1 × k2 × k3 × k4. Design wind pressure pz = 0.6 × Vz². Wind zones range from 33 m/s to 55 m/s across India.
IS 875-3 →
47 items shown
Basic Wind Speed — Major Cities (Vb in m/s)
50-year return period, 10m height, terrain category 2. Source: IS 875 Part 3 Appendix A.
City / FactorVb (m/s)ZoneState / Details
Ahmedabad39Zone IIIGujarat
Bangalore / Bengaluru33Zone IKarnataka
Bhopal39Zone IIIMP
Bhubaneswar50Zone VOdisha
Chandigarh39Zone IIIPunjab/Haryana
Chennai50Zone VTamil Nadu
Coimbatore39Zone IIITamil Nadu
Dehradun39Zone IIIUttarakhand
Delhi / New Delhi47Zone IVDelhi
Goa / Panaji39Zone IIIGoa
Guwahati50Zone VAssam
Hyderabad44Zone IVTelangana
Indore39Zone IIIMP
Jaipur39Zone IIIRajasthan
Jamshedpur47Zone IVJharkhand
Jodhpur39Zone IIIRajasthan
Kanpur47Zone IVUP
Kochi / Cochin39Zone IIIKerala
Kolkata50Zone VWest Bengal
Lucknow47Zone IVUP
Madurai39Zone IIITamil Nadu
Mangalore39Zone IIIKarnataka
Mumbai44Zone IVMaharashtra
Nagpur44Zone IVMaharashtra
Nashik39Zone IIIMaharashtra
Patna47Zone IVBihar
Port Blair44Zone IVAndaman
Pune39Zone IIIMaharashtra
Raipur39Zone IIIChhattisgarh
Ranchi39Zone IIIJharkhand
Shimla39Zone IIIHP
Srinagar39Zone IIIJ&K
Surat44Zone IVGujarat
Thiruvananthapuram39Zone IIIKerala
Vadodara44Zone IVGujarat
Varanasi47Zone IVUP
Vijayawada50Zone VAP
Visakhapatnam50Zone VAP
Terrain Categories (IS 875-3 Clause 5.3.2)
Determines k2 factor for height and terrain
City / FactorVb (m/s)ZoneState / Details
Category 1k2 = highestOpen sea, smooth flat landNo obstructions for > 500m
Category 2k2 = standardOpen terrain, scattered obstructions (3–10m)Farmland, few trees, airport
Category 3k2 = reducedSuburban, industrial, closely spaced obstructions (10m)Residential suburbs, town outskirts
Category 4k2 = lowestDense urban, city centreBuildings > 25m, city core
Design Wind Speed Factors
Vz = Vb × k1 × k2 × k3 × k4
City / FactorVb (m/s)ZoneState / Details
k1 (Risk Coefficient)0.82–1.07IS 875-3 Table 1k1=1.0 for 50yr return, 1.07 for 100yr
k2 (Terrain + Height)0.67–1.35IS 875-3 Table 2Varies with height (10m to 150m) × terrain
k3 (Topography)1.0 (flat) to 1.36IS 875-3 Clause 5.3.3Increased on hills, ridges, escarpments
k4 (Importance / Cyclone)1.0 to 1.15IS 875-3 Clause 5.3.41.15 for cyclone-prone coastal areas
Design Pressure (pz)pz = 0.6 × Vz²N/m² (Pa)e.g., Vz=47 m/s → pz = 1325 N/m²
Notes
• Basic wind speed is at 10m height above ground in open terrain (Category 2) for 50-year return period
• Cyclone-prone areas: entire east coast, Gujarat coast — use k4 = 1.15 and check for cyclonic wind speed
• For buildings < 10m in suburban areas, wind is rarely the governing load case — seismic may govern
• Wind load is critical for: tall buildings (>15 floors), industrial sheds, transmission towers, hoardings, chimneys
• Wind pressure on a surface = pz × (Cpe − Cpi) where Cpe = external pressure coefficient, Cpi = internal
• IS 875 Part 3 was revised in 2015 — ensure using the latest edition, not the 1987 version
• For temporary structures (1-year life): k1 = 0.82 — significantly lower design wind
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