Wind loading

Wind Load Calculator — IS 875 (Part 3):2015 (Phase 1)

Offline tool with embedded IS-875 tables, step-by-step log, CSV export and print report. Verify against official standard for final design.

Location, basic wind speed & code factors

Pick a city or zone (embedded Table 1). Terrain → automatic k₂ from embedded table (interpolated). k₃ choices cover common topography cases.

City (autocomplete)

Selecting a city sets V_b and zone from embedded Table 1 (illustrative). Clause ref: IS 875:2015 Table 1.

Wind zone (V_b, Table 1) Zone 1 — 33 m/s Zone 2 — 39 m/s Zone 3 — 44 m/s Zone 4 — 47 m/s Zone 5 — 50 m/s Zone 6 — 55 m/s

Basic wind speed V_b (m/s)

k₁ — Risk coefficient

Terrain category (for k₂) Category 1 — Open sea, flat unobstructed (Clause 6.3) Category 2 — Open plains with isolated obstacles Category 3 — Suburban / roughness with scattered obstructions Category 4 — Urban / forest with closely spaced obstructions

Structure reference height z (m)

k₂ — Terrain/height factor (derived)

Computed from embedded k₂ table (Clause 6.3 / Annex B). Override allowed.

k₃ — Topography factor k3 = 1.0 — flat / no special topography (Clause 6.4) Hill/crest factor (use conservative value) Escarpment, prominent ridge (site-specific)

Select based on site topography. Clause ref: 6.4.

k₄ — Importance / cyclonic factor Normal (k4 = 1.00) Important structure (k4 = 1.15) Essential / critical (k4 = 1.25)

Building / Roof / Opening selection (for C_r / C_p)

Building type Low-rise rectangular building (common) High-rise / tall Single-span roof / shed Pitched roof (gable)

Roof pitch (°) — for pitched roofs

External pressure (C_r / Cpe) choice Windward wall: +0.8 (use +0.8 as suction/pressure sign conv.) — Table ref Typical façade external (Cpe overall) — example values Leeward / suction zones Roof suction (pitched) — choose per roof pitch

Internal pressure (C_p) — enclosure Closed building — Cpi = -0.20 (Clause 7) Partially open — use ±0.20 (check openings area) Large openings — use +0.60 (worst-case)

Tributary area / Panel area A (m²)

Results

Design wind speed, pressures and member load. See detailed calculation log below with clause/table sources.

V_z (design wind speed)

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p_z (design pressure)

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p_net (net surface pressure)

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Member / joint load F

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Calculation log (engineering sheet)

No calculations yet. Use Compute to run step-by-step calculations. Values chosen from embedded tables will show their table/clause source.

Disclaimer & Notes

• Embedded tables and example coefficients are provided for convenience. Verify with the official IS 875 (Part 3):2015 document before using outputs for final design or submittals.
• k₂ interpolation uses embedded discrete heights and linear interpolation; for precise site design consult Annex B / clause tables in IS 875.
• For tall, flexible or long-span structures, perform dynamic/gust analysis as suggested in IS 875 (Part 3):2015.

Prepared: IS 875 (Part 3) — Phase 1 calculator (embedded tables). Verify values with official standard for final use.

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