SeriesCalc Logo

SeriesCalc

🌪️ ASCE 7-16 Wind Load Calculator

Calculate velocity pressure based on ASCE 7-16 standard for structural wind load design.

Inputs

Results

Velocity Pressure (q_z)
0.00 psf
Exposure Coefficient (K_z)
0.000

Wind Pressure Profile

z = 30 ftq_z = 0.0 psfV = 115 mph

Calculator Description

The ASCE 7 wind-load calculator follows the velocity-pressure method of the US standard ASCE 7-16 to compute the design wind pressure q_z at height z above ground. This q_z is the basis from which the actual wind load on walls and roofs is derived.

What this calculator finds

Enter basic wind speed V, exposure category (B/C/D) and height z to obtain the velocity pressure q_z and exposure coefficient K_z.

Why it matters

  • Wind-pressure-based structural design and safety checks for buildings, bridges and towers
  • Determining design loads for cladding (curtain walls, roofs) and fasteners
  • Comparing how terrain and exposure changes affect wind load

Formula

ASCE 7 Velocity Pressure

Velocity pressure q_z is the dynamic pressure of the basic wind speed multiplied by several influence coefficients; the leading constant differs by unit system.

Velocity Pressure (q_z)

Imperial:    qz=0.00256 KzKztKdV2\text{Imperial:}\;\; q_z = 0.00256\,K_z K_{zt} K_d V^{2}
Metric:    qz=0.613 KzKztKdV2\text{Metric:}\;\; q_z = 0.613\,K_z K_{zt} K_d V^{2}

Velocity Pressure Exposure Coefficient (K_z)

Kz=2.01(zzg)2/αK_z = 2.01\left(\dfrac{z}{z_g}\right)^{2/\alpha}

The design wind pressure on a surface is p = q_z · G · C_p, where G is the gust-effect factor and C_p the pressure coefficient.

  • V — Basic Wind Speed [mph (Imperial) or m/s (Metric)]
  • z — Height above ground level [ft (Imperial) or m (Metric)]
  • K_z — Exposure coefficient at height z [dimensionless]
  • K_zt — Topographic (hill/ridge) factor (usually 1.0)
  • K_d — Directionality/importance factor (usually 1.0)
  • Exposure B — α = 7.0, z_g = 1200 ft (Urban/Suburban)
  • Exposure C — α = 9.5, z_g = 900 ft (Open Terrain)
  • Exposure D — α = 11.5, z_g = 700 ft (Flat, Unobstructed/coastal)

How the formula works

  • q_z is proportional to V², so doubling wind speed quadruples the pressure.
  • Greater height z (less obstructed flow) raises K_z and thus pressure; Exposure D (coastal) is the most severe.
  • K_zt or K_d above 1 further increase pressure (e.g. hilltop sites).

Worked example

For Exposure C, z = 30 ft, V = 115 mph, K_zt = K_d = 1.0: K_z = 2.01·(30/900)^(2/9.5) ≈ 0.57, so q_z = 0.00256·0.57·1·1·115² ≈ 19.4 psf. In SI with V = 51.4 m/s, q_z = 0.613·0.57·51.4² ≈ 924 N/m² (≈ 19.3 psf).

Useful Tips

Practical tips

  • Pick the exposure category from terrain within roughly a 1-mile (1.6 km) radius; city clusters = B, open country = C, coastal/lake = D.
  • q_z is the dynamic pressure on the whole structure; the actual surface pressure needs G·C_p.
  • Unlike seismic load, wind scales with V², so read the local design wind-speed map carefully.

Limitations & cautions

  • This calculator stops at q_z; eccentricity, vortex shedding and dynamic aeroelastic response need separate analysis.
  • Wind standards differ by country (e.g. Korean KBC, Eurocode EN 1991-1-4); verify the applicable code for non-US projects.
  • Do not mix the constants (0.00256 vs 0.613) with the wrong wind-speed unit (mph vs m/s).