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Calcimator

Plate Girder Design Calculator

Design steel plate girders: check moment capacity, shear capacity, web and flange slenderness, and compactness.

Inputs

ft
kN/m
mm
mm
mm
mm
MPa

ASTM: A572 Gr.50 Fy=345 MPa (common); A36 Fy=250 MPa; A709 Gr.50W for bridge plate girders

Results

Moment Capacity (φMn)

3,310,459,821 N·mm

Shear Capacity (φVn)

1,446,868 N

Web Slenderness (h/tw)83.3
Flange Slenderness (bf/2tf)7
Compact Section?1 (1=yes, 0=no)
How to Use This Calculator
  1. Enter the design moment and shear in kip-ft and kips respectively.
  2. Set the web height-to-thickness ratio and flange dimensions.
  3. Input the steel yield strength and the unbraced length of the compression flange.
  4. Review the Section Modulus Provided, Flange Local Buckling ratio, and Web Slenderness check.
  5. Verify the Lateral-Torsional Buckling reduction factor to confirm the section is adequate.

How the result changes with Web Depth

Web DepthMoment Capacity (φMn)Shear Capacity (φVn)
4801,437,952,254 N·mm1,073,088 N
1,1804,037,283,991 N·mm1,446,868 N
2,0207,961,903,650 N·mm1,446,868 N
2,72011,902,192,228 N·mm1,446,868 N

What each input means

Span Length
Clear span of the plate girder.
Uniform Load
Total uniformly distributed load on the girder.
Web Depth
Clear depth of the web plate between flanges.
Web Thickness
Thickness of the web plate.
Flange Width
Width of each flange plate.
Flange Thickness
Thickness of each flange plate.
Steel Yield Strength (Fy)
Yield strength of the steel plate per AISC 360 §F13 (plate girders). ASTM A572 Grade 50: Fy=345 MPa (most common for plate girders); ASTM A36: Fy=250 MPa; ASTM A709 Gr.50W (weathering): Fy=345 MPa for bridges.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Span Length = 15, Uniform Load = 100, Web Depth = 1000, Web Thickness = 12 = 7 input(s) provided
  2. Calculate Moment Capacity
    Moment Capacity
    3310459821 = 3310459821
  3. Calculate Shear Capacity
    Shear Capacity
    1446868 = 1446868
  4. Calculate Web Slenderness
    Web Slenderness
    83.3 = 83.3
  5. Calculate Flange Slenderness
    Flange Slenderness
    7 = 7

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