What it checks
The module designs simply-supported composite steel beams for positive moment, supporting either solid slabs or metal deck. It applies the plastic stress distribution method to determine nominal flexural strength, accommodating both full and partial shear connection scenarios.
The design sequence begins with construction-stage checks, evaluating the bare steel section against dead loads and wet concrete weight. It then calculates the composite section strength using the effective slab width and modular ratio. Finally, the module verifies horizontal shear capacity by comparing stud connector demand against the capacity of headed studs, applying specific reduction factors for formed deck configurations.
Inputs
- Steel Geometry - Span (ft), gross area (in²), total depth (in), flange width (in), flange thickness (in), web thickness (in), moment of inertia (in⁴), plastic section modulus (in³), and elastic section modulus (in³).
- Material Properties - Steel yield strength (ksi), steel modulus (ksi), concrete compressive strength (psi), and concrete unit weight (pcf).
- Slab and Deck - Total slab thickness (in), deck rib height (in), deck rib width (in), and total effective slab width (in).
- Loads - Steel self-weight (plf), wet concrete dead load (plf), superimposed dead load (plf), and live load (plf).
- Connectors - Stud shank diameter (in), stud height after welding (in), and number of studs per rib.
- Design Parameters - Target composite ratio, live-load deflection limit denominator, total-load deflection limit denominator, and pre-set camber (in).
What it reports
- Concrete Modulus - Ec calculated in ksi using the concrete unit weight and compressive strength.
- Modular Ratio - The ratio of steel to concrete modulus, rounded to the nearest integer.
- Horizontal Shear - Full composite horizontal shear demand (kips) compared against the total shear strength provided by the studs.
- Stud Capacity - Nominal shear strength per stud (kips) including deck reduction factors, and the total number of studs required for full composite action.
- Composite Percentage - The actual composite percentage derived from the ratio of provided shear strength to full composite demand.
- Stress Block - Concrete stress block depth (in) and the distance from the top of steel to the concrete compression centroid (in).
- Neutral Axis - The plastic neutral axis depth from the top of steel (in), which is zero if all steel is in tension.
- Composite Strength - Nominal composite moment (kip·ft) and design strength (kip·ft) with a resistance factor of 0.90.
- Construction Check - Bare steel plastic moment (kip·ft) and design strength (kip·ft) compared against the dead-load moment acting on the bare steel.
Code references
The engine cites AISC 360-22 Chapter I for composite steel beams, specifically §I3.1a for effective slab width, §I3.2 for nominal flexural strength via plastic stress distribution, §I4.2 for horizontal shear, and §I8.2a for headed stud shear connector strength. It also references ACI 318-19 §19.2.2.1 for the concrete modulus calculation.
Limits
The module is limited to positive moment design and does not address negative moment or other loading conditions. The effective slab width is an echo of the input, meaning the caller must compute b_eff externally. The modular ratio rounding is a customary practice rather than a code rule. Results are engineering aids; the engineer of record is responsible for the design.