**Where you can use this:** [Atlas Tube HSS Connections Hub](https://connectionshub.atlastube.com/login/organisations?src=CALCSDOCS) only **Status:** Beta · **Region:** US · **Design codes:** AISC 360-22, AISC Design Guide 24 (2nd ed.) ## What this calculator does Sizes and checks an axial plate welded perpendicular to a round HSS chord: the connection you reach for with a brace, hanger or tie-back landing directly on a round chord face. The closest existing tools cover flat HSS moment connections with a flange plate, or round HSS truss connections between branch members, neither of which matches a plate welded flush and perpendicular to a round chord. Checking it by hand means working through Design Guide 24's round HSS punching shear and plastification tables alongside separate plate tension, compression and weld checks, then manually tracking which limits of applicability make those checks valid at all. ## Choosing a configuration A connection-type toggle selects between: | Configuration | Geometry | | ---------------- | ------------------------------------------------- | | T connection | Single plate on one chord face | | Cross connection | Two plates on opposite faces, reported separately | ## Inputting key properties You will find the calculator under the Connections tab. 1. **Select the connection type** (T or Cross). 2. **Select the HSS chord section and grade.** 3. **Enter the fillet weld size.** 4. **Enter the plate material properties.** On a Cross connection this material applies to **both** plates. 5. **Enter the plate geometry.** Width, thickness, length. On a Cross connection each plate's geometry is set **separately**, so the two plates do not have to match. 6. **Enter the plate effective length factor and unbraced length.** These are direct engineering inputs for the compression buckling check, not defaulted values, so set them to match your bracing conditions. 7. **Enter the required tension and compression axial demand.** On a Cross connection each plate takes its own loads. 8. **Enter the concurrent chord axial force and moment.** These feed the chord's own interaction into the governing stress ratio. ## Reviewing the calculations ### Limits of applicability, checked first The sheet evaluates AISC 360-22 Table K2.1A before anything else: chord wall slenderness (D/t), plate-to-chord width ratio, and chord material ductility. The entire Limit States section is gated on this check. If the limits are not met, the sheet shows a compliance message and no capacities, rather than reporting numbers you cannot rely on. ### Chord capacity at the connecting face | Limit state | Reference | | ------------------------------------- | ----------------------------------------------- | | Chord plastification | AISC 360-22 Table K2.1, DG 24 Tables 8-1 / 8-1A | | Chord shear yielding (punching shear) | AISC 360-22 Table K2.1, DG 24 Tables 8-1 / 8-1A | Both incorporate the chord's concurrent axial and moment interaction into the governing stress ratio. ### Plate and weld | Limit state | Reference | | ------------------------------------------------------------------------------------------------------ | ---------------------- | | Tensile yielding and rupture (gross and net section, no bolt holes) | AISC 360-22 J4.1, J4.3 | | Flexural buckling in compression | AISC 360-22 Chapter E | | Fillet weld capacity at a fixed 90 degree connection angle, with the 1.5 directional strength increase | AISC 360-22 Eq. J2-5 | ## Reading the results Governing ASD or LRFD utilisation per limit state, summarised separately for each plate on Cross connections. ## Assumptions and exclusions Plate loads are assumed to be **purely axial**. Moment and shear applied to the plate are not covered. If your brace, hanger or tie-back delivers anything other than axial load into the plate, this is not the right calculator. * Plates are assumed rectangular. * The connection angle is fixed at 90 degrees, which is what makes the 1.5 directional strength increase valid. * Plate is welded, not bolted: net section is taken as gross, with no bolt holes. * On Cross connections, plate material is shared but plate geometry and loads are per plate. ## Related * [Round HSS longitudinal plate connection](/docs/connections_hub/calculators/round_hss_longitudinal_plate)