Description
A helical stair is modeled as a three-dimensional frame consisting of beam elements.
Geometry
Radius to center line of stairs: 1.5[m]
Total vertical rise: 1.885[m]
Stair dimensions: 1.5[m] width x 0.15[m] depth
Modulus of Elasticity: 3,000,000; Poisson ratio: 0.3
Elements: 24 beam elements; Supports: Pinned
Loads
Beam load: FX3 = -1.0 t/m on all beams
Reference
The STRAP results were compared to those obtained using the SAP80 analysis program.
Comparison of Results
| Beam | Result type | Result | Deviation | |
| SAP80 | STRAP | |||
| 24 | M3 moment | -3.358 | -3.358 | – |
| 1 | Axial force | 2.796 | 2.796 | – |