Windbelasting — NEN-EN 1991-1-4 volledige afleiding

v_b,0 = 25 m/s (NL Zone 2, NEN-NA EN 1991-1-4 NA §4.2) c_dir = 1.0 (no directional factor in NL NA) c_season = 1.0 (no seasonal reduction in NL NA) v_b = c_dir × c_season × v_b,0 = 25 m/s

Terrain category II: z_0 = 0.05m, z_min = 5m z_e = h = 12m > z_min = 5m c_r(z) = k_r × ln(z/z_0) = 0.19 × ln(12/0.05) = 0.19 × ln(240) = 0.19 × 5.48 = 1.042 Air density ρ = 1.25 kg/m³ (standard) q_p(z_e) = (1+0.2×A) × 0.5×ρ×v_m² = use this v_m(z) = c_r(z) × v_b = 1.042 × 25 = 26.05 m/s

I_v(z) = σ_v/v_m = k_1/(c_0×ln(z/z_0)) = 1.0/(1×5.48) = 0.183 k_1 = 1.0 (turbulence factor) q_p(z) = [1 + 2×k_1×I_v(z)] × 0.5×ρ×v_m² = [1 + 2×0.183] × 0.5×1.25×26.05² = 1.366 × 0.625 × 678.6 = 579 N/m² = 0.579 kN/m²

d/h = 50/12 = 4.17, b/h = 30/12 = 2.5 Reference height h = 12m Zone D (windward): c_pe,10 = +0.7 Zone A (side): c_pe,10 = -1.1 (h/b < 4 → interpolate) Zone E (leeward): c_pe,10 = -0.4 Zone F/G (corners): c_pe,10 = -1.1 (local on edges) c_pe,1 = c_pe,10 + Δc_pe,D (if d/h > 4 use full reference) For cladding design, use cpe,1 for area < 1m²

With ±0.2 internal pressure: c_pi = +0.2 (worst case for outward load) w_total = q_p × (c_pe - c_pi) = 0.579×(0.7 - 0.2) = 0.290 kN/m² c_pi = -0.2 (worst case for inward load) w_total = 0.579×(-1.1 - (-0.2)) = -0.579×0.9 = -0.521 kN/m² c_f = 1.2 (friction coefficient, if applicable) Cladding panel design: w_design = 0.52 kN/m² (inward) = 0.29 kN/m² (outward) — governs for fixings Use spreadsheet and structural glazing program for area-dependent cpe Friction loads: F_fr = q_p(z) × c_f × A_rear for area > 10m²