Steel Grating Design Data

Steel grating is widely used in industries, mining, construction, buildings and other fields. When we need steel grating products, send the order with the detailed description. Well, learning the steel grating design nomenclature is very important.

Here are the grating design nomenclature.

  • b = thickness of rectangular bearing bar, inches.
  • d = depth of bearing bar, inches.
  • Aw = center to center distance between bearing bars in welded and press-locked gratings, inches.
  • C = concentrated load at mid-span = 4FSw/L pounds per foot of width (pfw).
  • Dc = deflection under concentrated load = CL3/48 EIw  inches.
  • Du = deflection under uniform load = 5UL4/12 (384) EIw  inches.
  • E = modulus of elasticity, pounds per square inch (psi)
    • Steel: E = 29,000,000 psi = 29 (10)6.
    • Stainless Steel: E = 28,000,000 psi = 28 (10)6.
    • Aluminum: E = 10,000,000 psi = (10)7.
  • F = allowable fiber unit stress, psi
    • ASTM A-1011: F = 18,000 psi (Steel, Carbon Hot Rolled Sheet and Strip, Commercial Quality AISI 1020).
    • ASTM A-36:   F = 20,000 psi (Structural Steel (Bars only)).

    • ASTM A167:   F = 20,000 psi (Type 304 and 316, Stainless Steel)

      F = 16,500 psi (Type 304L and 316L, Stainless Steel).

    • ASTM B-221: F = 12,000 psi (6061-T6  Alloy)

      F = 10,000 psi (6063-T6  Alloy).
  • Lb  = moment of inertia of a rectangular bar = bd3/12 in4.
  • Lw  = moment of inertia of grating per foot of width = KI in4.
  • K = number of bearing bars per foot of grating width = 12/Aw.
  • L = span of grating between reaction points, inches.
  • Mb = maximum bending moment of bearing bar, in-lbs.
  • Mw = maximum bending moment of grating per foot of width, in-lbs.
  • Mu = maximum bending moment under uniform load = FSw= UL2/96in-lbs.
  • Mc = maximum bending moment under concentrated load = FSw = CL/4 in-lbs.
  • Sb = section modulus of a rectangular bar = bd2/6 in.3.
  • Sw = section modulus per foot of grating width = KSb in.3.
  • U = uniform load = 96fSw/L2 psf = 96 M/L2  pounds per square foot (psf).

Sample calculation: steel

  • Type of Grating = 19-W-4-63 welded carbon steel grating.
  • Size of Bar = 1-1/2 × 3/16.
  • Span = 54 inches.
  • Aw = bearing bar spacing = 1.1875 inches.
  • K = number of bearing bars in panel width = 12/Aw = 12/1.1875 =10.105.
  • F = allowable fiber stress = 18,000 psi.
  • E = 29,000,000 psi.
  • Sw = section modulus of grating per foot of width = Kbd2/6 = 10.105 × 0.1875 (1.5)2/6 = 0.711 in.3.
  • Iw = moment of inertia of grating per foot of width = Kbd3/12 = 10.105 × 0.1875 (1.5)3/12 = 0.533 in.3.
  • Mw = maximum bending moment for grating per foot of width = FSw =18,000 × 0.711 = 12,800 in.-lbs.

Allowable Concentrated Load and Deflection for 19-W-4-63:

  • C = allowable load = 4 Mw/L = 4 × 12,800/54 = 948 pfw.
  • Dc = deflection = CL3/48EIw = 948 × 543/(48 × 29 × 106 × 0.533) =0.201 inches.

Allowable Uniform Load and Deflection  for 19-W-4-63:

  • U = allowable load = 96 Mw/L2 = 96 × 12,800/542 = 421 psf.
  • Du= deflection = 5UL4/4608EIw =5 × 421 × 544/(4608 × 29 × 106 × 0.533)= 0.251 inches.