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Calcimator

Composite Beam Design Calculator

Design steel-concrete composite beams: calculate composite capacity, PNA location, required shear studs, and strength gain.

Inputs

mm
mm²
MPa
mm
mm

AISC 360 §I3.1a: each side = min(L/8, beam spacing/2, slab edge); total effective width = sum each side

MPa
mm

AISC 360 §I8.2: 16 mm (5/8"); 19 mm (3/4", most common); 22 mm (7/8"); max = 2.5× flange thickness

studs

Results

Composite Compression Force

2,932,500 N

Required Shear Studs

24 studs

PNA Location (from top)57.5 mm
Deflection Reduction60%
Strength Gain vs Non-Composite48.1%
How to Use This Calculator
  1. Enter the beam span in feet and the tributary width in feet.
  2. Input the slab thickness, concrete compressive strength, and steel yield strength.
  3. Set the total superimposed dead load and live load in psf.
  4. Review the Required Section Modulus and the Recommended Wide-Flange Section.
  5. Verify the Shear Stud Count and spacing against AISC composite design requirements.

How the result changes with Steel Cross-Section Area

Steel Cross-Section AreaComposite Compression ForceRequired Shear Studs
10,4503,605,250 N29 studs
35,3256,375,000 N52 studs
65,1756,375,000 N52 studs
90,0506,375,000 N52 studs

What each input means

Steel Beam Depth
Total depth of the steel W-shape beam.
Steel Cross-Section Area
Total cross-sectional area of the steel beam.
Steel Yield Strength
Yield strength of the steel beam. A992 = 345 MPa.
Concrete Slab Thickness
Thickness of the concrete slab above the metal deck.
Effective Slab Width
Effective width of concrete slab acting with the steel beam per AISC 360 §I3.1a. Use smallest of: beam span/8 each side of beam centerline; distance to adjacent beam centerline/2; or distance to slab edge.
Concrete Strength (f'c)
Compressive strength of the concrete slab.
Shear Stud Diameter
Diameter of headed shear studs per AISC 360 §I8.2. Common sizes: 16 mm (5/8"), 19 mm (3/4", most common), 22 mm (7/8"). Maximum diameter per AISC I8.1: stud ≤2.5× flange thickness for non-deck conditions.
Provided Stud Count
Total number of shear studs provided between zero and maximum moment.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Steel Beam Depth = 400, Steel Cross-Section Area = 8500, Steel Yield Strength = 345, Concrete Slab Thickness = 125 = 8 input(s) provided
  2. Calculate Composite Compression Force
    Composite Compression Force
    2932500 = 2932500
  3. Calculate Required Shear Studs
    Required Shear Studs = max(requiredStuds
    24 = 24
  4. Calculate PNA Location
    PNA Location
    57.5 = 57.5
  5. Calculate Deflection Reduction
    Deflection Reduction
    60 = 60

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