> ## Documentation Index
> Fetch the complete documentation index at: https://calcs.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# HSS to HSS Moment Connection
> Design fin plate and stiffened HSS moment connections, including beams framing into both faces of the column.
**Where you can use this:** [Atlas Tube HSS Connections Hub](https://connectionshub.atlastube.com/login/organisations?src=CALCSDOCS) and [Calcs.com](https://app.calcs.com/login?src=calcsdocs)
**Status:** Beta · **Region:** US · **Design codes:** AISC 360-22 Chapter K, AISC Design Guide 24 (2nd ed.)
## 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.
| Connection type | Preset | Detail |
| --------------- | --------------------- | ------------------------------------------------------------------- |
| Fin Plate | `Fin Plate` | Plate welded to the column face, beam bolted or welded to the plate |
| Stiffened | `Field-Welded Seated` | Flange plates transferring moment into the column walls |
## Video walkthrough
The [Fin End Plate shear connection video](https://www.youtube.com/watch?v=eF3WoXdclMo) covers the fin plate geometry from the shear side.
## Beam location: one side or two sides
Set **Beam Location** to match your node.
| Setting | Joint | When to use |
| --------- | ------------ | --------------------------------------------------------------------------- |
| One side | T connection | Perimeter columns, end of a frame line |
| Two sides | X connection | Interior nodes in multi-storey frames, industrial structures, floor framing |
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.
### 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.
## 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.
## 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.
## 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.
| Limit state | Reference |
| ------------------------------------------------------- | ---------------------------- |
| HSS sidewall local yielding | AISC 360-22 Chapter K |
| Punching shear: column plastification or shear yielding | AISC 360-22 Chapter K |
| Sidewall buckling induced by the flange plate | AISC 360-22 Chapter K, DG 24 |
| Plate yielding, rupture and block shear | AISC 360-22 J4.1, J4.2, J4.3 |
| Bolt shear, bearing and tearout | AISC 360-22 J3.7, J3.11 |
| Weld capacity | AISC 360-22 J2.4 |
## Related
* [WF beam to concrete-filled HSS moment connection](/docs/connections_hub/calculators/wf_to_concrete_filled_hss_moment)
**Where you can use this:** [Atlas Tube HSS Connections Hub](https://connectionshub.atlastube.com/login/organisations?src=CALCSDOCS) and [Calcs.com](https://app.calcs.com/login?src=calcsdocs)
**Status:** Beta · **Region:** US · **Design codes:** AISC 360-22 Chapter K, AISC Design Guide 24 (2nd ed.)