Description
A grid in the form of a circular ring beam rests on three equally spaced simple supports. A concentrated load is applied midway between two of the supports.
Geometry
Radius: 100 in.
Elements: 36 identical beams.
Property: Round bar, diam = 2.7 in.
Material: E = 107 lb/in2; Poisson ratio = 0.3
Supports: 3 equally spaced pinned supports (X3)
Loads
Concentrated load: 1000 lb (X3 direction)
Reference
Raymond J Roark, Roark’s Formulas for Stress and Strain, Fourth Edition. (Table XIX – Case 3), 1965 4th edition, McGraw – Hill book company.
Calculation
The STRAP model consists of 36 straight beam segments, i.e. the model is not continuously circular. This leads to a slight discrepancy in the results.
Comparison of Results
| Beam | Result type | Result | Deviation | |
| Theoretical | STRAP | |||
| 18 | M2 moment | 38490 | 38344 | 0.38% |
| 1 | M2 moment | 19250 | 19172 | 0.41% |
| 6 | MT moment | -8790 | -8721 | 0.78% |
| 15 | MT moment | 13100 | 13225 | 0.95% |