Interpreting Results
After analysis, check these in order:
| # | Check | Where to Look | Pass Criteria |
|---|---|---|---|
| 1 | Unity Check | Results tab, or Unity Check visualization | All members < 1.0 |
| 2 | Deflection | Deflection summary | Within TIA-222-H limits |
| 3 | Base Reactions | Results tab — Reactions | Within foundation capacity |
| 4 | Member Forces | Elements tab | No unexpected tension/compression |
Reading Unity Check Ratios
The unity check ratio is the single most important number:
Unity Check = Demand / Capacity
- < 0.5 — Significantly under-utilized (could optimize with smaller profiles)
- 0.5 – 0.85 — Efficient design range
- 0.85 – 1.0 — Acceptable but tight
- > 1.0 — FAILS — member is overstressed
If Members Fail
When unity check ratios exceed 1.0:
- Identify which members fail — use the Unity Check visualization to spot red members
- Check the member family — are legs failing? Diagonals? Horizontals?
- Increase profile size for the failing family in that section
- Re-run analysis and check again
- Repeat until all members pass
tip
Start by fixing the most critical member (highest unity check ratio). Often, strengthening the legs in the bottom sections resolves multiple failures because it reduces deflection and redistributes forces.
Checking Deflection
Maximum horizontal displacement at the tower top:
- Service limit: H/200 (tower height ÷ 200) per TIA-222-H
- Example: 54m tower → max deflection = 270mm under service wind
Checking Base Reactions
Base reactions tell you what the foundation must resist:
- Vertical (Fy) — compression from dead load + overturning, or uplift
- Horizontal (Fx, Fz) — lateral base shear from wind
- Moments (Mx, My, Mz) — overturning and torsional moments
Use the governing load combination's base reactions for foundation design.