E12 : Eigenvalue Analysis of a simply supported beam

A simply supported beam is analyzed to determine the fundamental frequency. Determine the fundamental frequency.
Analysis Type
2-D eigenvalue analysis (X-Z plan)
Unit System
in, lbf
Dimension
Length 80in
Element
Beam element
Material
Modulus of elasticity E = 30.0×10^6psi
Weight density γ = 0.281 lbf/in^3
Sectional Property
Rectangular cross-section: b = 2 in, h = 2 in
Boundary Condition
Node 1, 5: Constrain DX and DZ
Analysis Case
Eigenvalue analysis
References
Thomson, W. T., (1965). “Vibration Theory and Application”, Prentice Hall, Englewood Cliffs, N. J.


TheoreticalMIDASOpenBrim

Percent Difference

(MIDAS vs Theoretical)

Percent Difference

(OpenBrim vs Theoretical)

Mode 1 

Frequency (Hz)28.76628.75928.74510.02%0.07%
Period (sec)0.03480.0350.03480.6%0%