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# HSS to HSS Splice Gusset Connection (Shuriken)
> Design a bolted round HSS column splice using four shop-welded gusset plates and field-bolted splice plates, to AISC 360-22.
**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, ASCE 7-16
## What this calculator does
Designs and checks a splice between two round HSS columns built as the Atlas Tube Shuriken detail: four gusset plates shop-welded to each half-column at 90 degree intervals, joined across the gap by field-bolted splice plates.
Round HSS columns are specified for their appearance and efficiency, but splicing them is awkward. There is no flange to bolt to, so fabricators fall back on welded ring plates or full-penetration field welds, both expensive, slow and hard to inspect on site. The bolted gusset detail solves the constructability problem, but nothing off the shelf checks it: the engineer has to convert the column moment into a tension-compression couple across opposing gusset groups, track demand at two different planes, then chase more than a dozen limit states across the column wall, the gussets, the splice plates, the bolt group and the weld.
## Video walkthrough
## Inputting key properties
1. **Select ASD or LRFD.**
2. **Select the round HSS column section and grade.** ASTM A500 Grade C or A1085.
3. **Enter gusset and splice plate thickness, widths and setbacks.**
4. **Enter the weld size.**
5. **Enter bolt properties:** size, grade, thread condition, number of bolts per vertical row, spacing.
6. **Set slip-critical behaviour:** whether the joint is slip-critical, and the faying surface class.
## Applying loads
Enter axial load and moment either as individual load types, with ASCE 7-16 combinations generated automatically, or as pre-factored loads. Column reactions can also be linked in from a member sheet.
### How moment is resolved
Applied moment is resolved into an equivalent tension-compression couple by idealising the round column as two opposing halves aligned with the plane of bending. Distinct lever arms are used at the column and weld plane and at the bolted connection plane, so each limit state sees the demand where it actually acts.
## Reviewing the calculations
### Column limit states
| Limit state | Reference |
| ------------------------------------------------------- | ------------------------------------------------ |
| Bearing in compression | AISC 360-22 J7 |
| Tensile yielding and rupture, including shear lag | AISC 360-22 J4.1, J4.3, Table D3.1 |
| Wall slenderness and section classification for flexure | AISC 360-22 Chapter F |
| Wall plastification and punching shear | AISC 360-22 K2 and the Steel Construction Manual |
### Connection limit states
| Limit state | Reference |
| ----------------------------------------------------------------------- | ---------------------- |
| Bolt shear and slip-critical resistance | AISC 360-22 J3.7, J3.9 |
| Splice plate tensile yielding and rupture | AISC 360-22 J4.1, J4.3 |
| Bolt bearing and tearout, splice and gusset plates | AISC 360-22 J3.11 |
| Block shear rupture | AISC 360-22 J4.3 |
| Gusset plate shear yielding and rupture at the weld | AISC 360-22 J4.2 |
| Gusset plate flexural yielding and rupture from the eccentric bolt load | AISC 360-22 J4.5 |
| Axial and flexural interaction in the gusset | AISC 360-22 H1.1 |
| Fillet weld group joining gusset to column | AISC 360-22 J2.4 |
| Minimum HSS wall thickness to develop the weld shear strength | AISC 360-22 J2.4 |
### Dimensional checks
The sheet polices minimum and maximum weld size, minimum and maximum bolt spacing, vertical and transverse edge distances, splice-to-gusset thickness compatibility, and the minimum splice length needed for the Table D3.1 shear lag formula to remain valid.
## Reading the results
Results are grouped into compression, tension, gusset and weld capacity summaries, showing governing demand-capacity ratios. Whole-connection and per-gusset-splice-group (moment) checks run in parallel, with the governing load combination reported separately for axial and for moment. The connection diagram redraws with the input geometry.
## Assumptions and exclusions
Only round HSS columns and the bolted-with-welded-gusset configuration are supported. The moment path requires a compact section: non-compact or slender walls are flagged rather than designed.
## Related
* [HSS to HSS splice connection (end plate)](/docs/connections_hub/calculators/hss_to_hss_splice_end_plate)
**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, ASCE 7-16