Wind load

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

Compute design wind speed, pressure, net surface pressure and member/joint loads

Inputs (Step 1 & 2)

Enter basic wind speed and factors

Basic wind speed V_b (m/s)

k₁ — Risk coefficient

k₂ — Terrain / height factor

k₃ — Topography factor

k₄ — Importance / cyclonic factor

Calculation notes

Design wind speed V_z = V_b × k₁ × k₂ × k₃ × k₄. Design wind pressure p_z = 0.6 × V_z² (N/m²).

Step 3 & 4 — Pressure & coefficients

External pressure coefficient C_r

Internal pressure coefficient C_p

Combine internal pressure as (p_z × C_r) + (p_z × C_p) — internal adds to external (p_z × C_r) - (p_z × C_p) — internal subtracts (suction)

Tributary area for member/joint (A) (m²)

Result units N/m² (pressure) kN/m²

V_z (design wind speed)

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p_z (design wind pressure)

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p_net (net surface pressure)

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Member / joint load F (= p_net × A)

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Extras

Copy results or export as CSV for reports.

Calculation log (detailed)

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Notes & guidance

• Basic wind speed V_b must be taken from IS:875 (Part 3) map / Table 1 for the site location.
• Choose appropriate terrain (k₂), topography (k₃) and importance/cyclonic factors (k₄) as per code clauses.
• Check sign conventions for C_r and C_p (windward pressure usually positive, suction negative — library inputs shown as examples).
• For tall / flexible structures, run dynamic / gust analysis separately — this tool gives quasi-static surface loads per IS 875.

Prepared as a reference implementation of IS 875 (Part 3):2015 method. Verify with standard and site-specific clauses before using for design.