Пролёт, нагрузка и порода дерева → рекомендуемое сечение балки
The floor beam calculator selects the minimum timber cross-section for a floor joist based on span, load category, wood species and joist spacing, using bending moment and allowable stress.
q = load × spacing (kg/m). M = q × L² / 8 (kg·m). Required section modulus W = M × 100 / (σ × 10) cm³. With h/b = 1.5: b = (W / 0.375)^(1/3). Nearest standard section is selected.
Span 4 m, residential load 350 kg/m², pine (σ = 13 MPa), spacing 0.6 m: q = 210 kg/m, M = 420 kg·m, W ≈ 323 cm³ → section 100 × 200 mm.
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