Here’s a clear breakdown of the four key steel structural elements, their roles, and differences:

1. Steel Columns

Function: Vertical load-bearing members that transfer loads from beams/girders to foundations.
Types:

• H-Section (Wide-flange): Most common, resists bending in both axes

• Tube/Hollow Section: For axial loads, better torsional resistance

• Built-Up: Custom plates/welded sections for heavy loads
  Key Properties:

• High compressive strength

• Slenderness ratio (KL/r) critical for buckling resistance

• Fireproofing often required

2. Steel Beams

Function: Horizontal members supporting floors/roofs, transferring loads to columns.
Common Types:

• Bending capacity (Moment of Inertia, Iₓ)

• Deflection limits (L/360 for floors)

• Composite action with concrete decks

3. Steel Girders

Function: Primary horizontal members supporting beams or direct loads (heavier than beams).
Key Differences vs. Beams:

• Plate Girders: Custom-built welded I-sections for bridges

• Box Girders: Closed sections for torsion resistance

4. Steel Bracing

Function: Provides lateral stability against wind/earthquakes by forming triangular rigidity.
Common Systems:

• Slender members designed for tension-only

• Buckling resistance in compression

• Gusset plate connections critical

Comparison Table

Key Engineering Insights

• Columns/Beams: Governed by AISC 360 (US) or Eurocode 3 (EU)

• Girders: Often require stiffeners to prevent web buckling

• Bracing: Reduces lateral drift by 30-50% in tall buildings

• Material Savings: Hollow sections use 20% less steel than open sections for same load