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Atlas TubeAtlas TubeWhere you can use this: Atlas Tube HSS Connections Hub and Calcs.comStatus: Beta · Region: US · Design codes: AISC 360-22 Chapter K, AISC Design Guide 24 (2nd ed.)

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What this calculator does

Designs a moment connection between an HSS beam and an HSS column, in two connection types, with the beam framing into one or both faces of the column.

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Video walkthrough

The Fin End Plate shear connection video covers the fin plate geometry from the shear side.

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Beam location: one side or two sides

Set Beam Location to match your node. At interior nodes the loads from both beams interact on the shared HSS column walls, so the column cannot be checked face by face in isolation. Before two-sided support existed, engineers either performed manual interaction checks on the column wall capacity or applied conservative assumptions that ignored load redistribution between sides.

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What Two Sides changes

  • Independent applied load tables for the left and right beam: axial (tension and compression), shear, and moment (positive and negative), for both LRFD and ASD combinations.
  • Demands are aggregated at the column node to compute the required axial strength in the HSS column (P_ro,c) correctly from both beam shear contributions.
  • Seismic load inputs (E_v and E_h) are defined independently for each beam and factored into the governing combinations for both sides.
  • The dynamic connection diagram mirrors the beam geometry to reflect the two-sided configuration.

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Inputting key properties

  1. Select the connection type, Fin Plate or Stiffened.
  2. Set Beam Location, One Side or Two Sides.
  3. Select the beam and column HSS sections and grades.
  4. Enter the plate geometry and weld sizes.
  5. Enter bolt properties where the connection type uses them.

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Applying loads

Enter axial, shear and moment per beam. With Two Sides selected you get a second, independent load table. Seismic components are entered per beam.

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Reviewing the calculations

Column wall limit states are evaluated under the combined demand, so the governing envelope at the column face is resolved correctly for interior nodes. Limit states are grouped by element: beam, end plate, fin plate, bolt capacity, welds, and HSS column.
Some column limit states only appear once the load case calls for them. Apply compression on both beams at an interior node and a buckling of HSS sidewalls check appears that is not present with a single beam.