Members/Stairs

RC Stairs

Waist-slab flight designed as a one-way slab on the horizontal span (EN 1992-1-1)

Geometry
Loads and materials
Stair design passes · pitch 35.0° · span 2.55 m · self-weight 7.07 kN/m² (plan)
Reinforcement
  • Main (bottom): Ø8 @ 200 mm (251 mm²/m)
  • Distribution: Ø8 @ 275 mm
Detail drawing
Stair flight: 10 risers of 175 mm, going 250 mm, waist 160 mm2.25 m on plan (9 goings)1.75 mMain Ø8@200 (bottom, along the slope)Distribution Ø8@275cover 25 mm · bars shown schematically · landings drawn at 1.2 m each side
3D view

Checks

  • OKRiser height 175 mm (typical 150–220)
  • OKGoing 250 mm (≥ 220 typical minimum)
  • OK2R + G rule 600 mm (550–700, ideal 600–640)
  • OKPitch 35.0° (≤ 42° for private stairs)
  • OKFlexure lx 251 ≥ 231 mm²/m
  • OKMain bar spacing 200 ≤ min(3h, 400) = 400 mm [9.3.1.1(3)]
  • OKShear (VEd ≤ VRd,c) 17.6 ≤ 71.0 kN/m
  • OKDeflection (l/d) 19.5 ≤ 97.7

Calculation

Actions (per m²)EN 1990 6.4.3.2
Self-weight25 h4.00 kN/m²
Design load wEdExp. 6.1015.39 kN/m²
Flexure: lx direction, sagging (simply supported)EN 1992-1-1 3.1.7, 9.3.1
Mcoefficient × w L²12.51 kNm/m
dh − c − φ/2 (− inner layer allowance)131 mm
KM / (b d² fck)0.0243
zd [0.5 + √(0.25 − K/1.134)] ≤ 0.95 d124 mm
As,reqM / (fyd z)231 mm²/m
As,minmax(0.26 fctm/fyk b d, 0.0013 b d)197 mm²/m
ProvidedØ8 @ 200 mm = 251 mm²/m
Shear (no links)EN 1992-1-1 6.2.2
VEd at dcoef · w L − w d17.6 kN/m
VRd,c[CRd,c k (100 ρl fck)^(1/3)] b d ≥ vmin b d71.0 kN/m
Deflection (span/depth)EN 1992-1-1 7.4.2
K (structural system)Table 7.4N1.00
Allowable l/d97.7
Actual l/dlx / d19.5

Scope: single flight, UDL per plan area, waist-slab type, effective span measured horizontally. Results are an aid only and must be verified by a qualified, licensed engineer before use. National Annex presets are recommended values and must be checked against the official documents.