Terminology

• W shape: wide-flange section; W18x35 is about 18 in. deep and 35 lb per ft
• Girder / beam / filler beam: primary member carrying beams, secondary members, and infill beams
• Composite beam: beam acting with the concrete slab through welded shear studs
• Camber: upward curve fabricated into long beams to offset dead load deflection
• Simple shear connection: bolted clip angle, single plate, or seat that carries shear only
• Moment connection: welded or bolted connection that carries bending for lateral frames
• Coping: cut flange at a connection to clear the supporting member
• Web opening / castellated beam: holes or expanded webs for ducts and pipes
• SFRM / intumescent: spray-applied or thin-film fireproofing
• AESS: architecturally exposed structural steel, with finish categories AESS 1 to 4

Standards

Ratings

• Material: ASTM A992, Fy 50 ksi and Fu 65 ksi, is the preferred specification for wide-flange shapes
• Depth to span: depth governs stiffness, vibration, and plenum space; deeper beams reduce deflection
• Vibration: floor framing evaluated per AISC Design Guide 11 for walking vibration

Test standards

• AISC 360: specification for structural steel buildings
• AISC 341: seismic provisions where a seismic force-resisting system uses steel
• AISC 303: code of standard practice
• ASTM A992: structural shapes
• AWS D1.1: structural welding

Materials

• ASTM A992 W shapes: standard for beams and columns
• High-strength bolts: ASTM F3125 (A325 and A490 grades)
• Shear studs: welded through deck to the beam
• Coatings: shop primer, galvanizing for exterior exposure, fireproofing per rated design

Detailing

• Coordinate beam depths with MEP mains; locate web openings with the engineer
• Specify AESS category for exposed steel
• Fireproofing type and thickness follow the listed design for the required rating
• Provide camber for long spans and check ponding on roofs
• Isolate exterior steel from interior steel to avoid thermal bridging at canopies and balconies

Uses

Specific uses

• Office, hospital, and school floor framing
• Long-span roofs and transfer girders
• Moment frames and braced frame beams
• Mezzanines, canopies, and equipment platforms
• Steel-framed residential and hotel buildings

Pros and cons

Pros

• High strength-to-weight ratio and long spans
• Fast erection; prefabricated members
• Easy to modify and reinforce later
• Recyclable with high recycled content

Cons

• Needs fire protection in most rated construction
• Floor vibration can govern long spans
• Corrosion protection needed in exposed or humid conditions
• Price swings with steel markets

Manufacturing and cost

Construction

• Rolled at mills; fabricated with holes, copes, and connections in the shop
• Erected by crane; bolted and welded; inspected per special inspection program

Main manufacturers and suppliers

• Nucor
• Gerdau
• Steel Dynamics

Trade association: American Institute of Steel Construction.

Typical costs

• Structural steel, fabricated and erected: about $2,000 to $4,000 per ton
• Material alone about $1,900 to $3,400 per ton; fabrication and erection about $1,000 to $2,100 per ton

Sources

• AISC: are you properly specifying materials, https://www.aisc.org/globalassets/modern-steel/archives/2018/04/areyouproperlyspecifyingmaterials.pdf
• UpCodes: 2024 IBC Chapter 22 steel, Chapter 22 Steel: Department of Defense Building Code 2024 | UpCodes
• New Rising Sun Arts Centre: cost of structural steel per ton, 2026, https://new.risingsunartscentre.org/news/cost-of-structural-steel-per-ton-2026.html
• Building Club: steel beam weight calculator and pricing, https://pro.buildingclub.info/en/steel/steel-beam-weight-calculator-ft-lbs/
• Wikimedia Commons: I-BeamCrossSection.svg, by Roulex45 and Bban (CC BY-SA 3.0), https://commons.wikimedia.org/wiki/File:I-BeamCrossSection.svg