Frame structure: Beams and columns

1. Columns

• Function:

  • Transmit loads from beams, floors, and roofs to the foundation.

  • Mainly withstand compression, sometimes with additional bending loads (due to wind, earthquakes).

• Characteristics:

  • Always placed vertically.

  • Have a H, I, round, square, or steel box section.

  • Size and section depend on the building height and structural load.

• Connection:

  • Rigidly connected to the foundation with anchor bolts.

  • The upper part of the column is connected to the beam with high-strength bolted connections or welded connections.

• Column Classification:

  • Edge columns: located at the edge, bearing roof load + wind load.

  • Interior columns: bearing roof load + load from the largest beam.

  • Corner columns: connected in two directions, bearing complex forces.

2. Beams

• Function:

  • Support floors, roofs, and transmit lateral loads to columns.

  • Mainly withstand bending, may have additional shear and torsion forces.

• Characteristics:

  • Located horizontally, connecting between columns.

  • Can be I-shaped steel beams, H-beams, box beams, or composite steel plate beams.

• Connection:

  • Beams are connected to columns by bolts/welding.

  • Can be pinned connections (transmitting only shear forces) or rigid connections (transmitting both moment and shear).

• Beam Classification:

  • Main beams: directly receive loads from floors, roofs → transmit to columns.

  • Secondary beams: support loads from floor/roof slabs and then transmit them to main beams.

  • Purlins: small beams used to support metal roofs or light floors.

3. Relationship between Beams and Columns in the Frame

• Beams are horizontally connected, columns are vertically connected, forming a strong 3D frame.

• Columns receive loads from beams and transmit them to the foundation.

• Beams help stabilize columns, prevent overturning, and prevent lateral bending.

• When combined → form the main load-bearing frame system for prefabricated steel structures, industrial buildings, and high-rise buildings.