Description
A simply supported rectangular beam, subject to a concentrated weight at the mid-point.
Geometry
Span length: 10.0
Section Dimension: 0.5 x 0.5
Modulus of Elasticity: 21,000,000
Poisson ratio: 0.3
Elements: 10 equal beam elements
Supports: Pinned supports at both ends
Loads
Nodal weights: 100.0 tons at mid-span
Reference
Raymond J Roark, Roark’s Formulas for Stress and Strain, Sixth Edition. (Table 36- Case 1), 1965 4th edition, McGraw – Hill book company.
Calculations
f = (6.93/2p) √(EIg/Wl3)
Comparison of Results
| Result type | Result | Deviation | |
| Theoretical | STRAP | ||
| Natural frequency – Mode 1 | 3.6123 | 3.5982 | 0.39% |