← Verification — Linear (Frames & Trusses)
V2.2 — 4-leg space (tripod) truss
ExactDescription
A four-legged three-dimensional (tripod) pin-jointed truss under a vertical apex load — the 3-D counterpart to V2.1, exercising out-of-plane truss geometry.
Reference
Symmetry, method of joints and virtual work (closed form): F = PLm/(4h) (compression), δ = PLm³/(4h²EA).
Model
Four axial truss members arranged symmetrically in plan, meeting at a shared apex node above them, each pinned to its own ground support, under a vertical load applied at the apex.
| Apex load, P | 40 kip |
| Base half-spacing, a | 60 in |
| Height, h | 90 in |
| Member length, Lm | 123.69 in |
| Elastic modulus, E | 29,000 ksi |
| Member area, A | 3 in² |
Comparison
| Quantity | Reference | vfopro | % diff | Status |
|---|---|---|---|---|
| Apex vertical deflection (in) | -0.0269 | -0.0269 | +0.00% | Exact |
| Apex horizontal deflection x (in) | 0 | 0 | n/a | Exact |
| Apex horizontal deflection y (in) | 0 | 0 | n/a | Exact |
| Leg 1 axial force (kip, +tension) | -13.74 | -13.74 | +0.00% | Exact |
| Leg 2 axial force (kip, +tension) | -13.74 | -13.74 | +0.00% | Exact |
| Leg 3 axial force (kip, +tension) | -13.74 | -13.74 | +0.00% | Exact |
| Leg 4 axial force (kip, +tension) | -13.74 | -13.74 | +0.00% | Exact |
| Base 1 vertical reaction (kip) | 10 | 10 | 0.00% | Exact |
| Base 2 vertical reaction (kip) | 10 | 10 | 0.00% | Exact |
| Base 3 vertical reaction (kip) | 10 | 10 | 0.00% | Exact |
| Base 4 vertical reaction (kip) | 10 | 10 | 0.00% | Exact |
Conclusion
Every reported quantity matched the closed-form value to at least 6 significant figures.
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Last updated September 22, 2026 · applies to vfopro 20260922.0.0 or later