A simply supported beam is subjected to its own weight. The span length is 80 inches and the beam is steel with 2 inches square cross section. The mass density of the beam is 0.000728 lb-sec2/in4. Determine the fundamental frequency of the beam.

The model of the beam has 5 joints and 4 beam elements. Joints 1 and 5 are pin supports. The joints 2, 3 and 4 represent the lateral dynamic degrees of freedom.

Modulus of Elasticity = 30,000,000 psi

Span Length = 80 inches

A = 4 in2

Izz = 1.3333 in4

Weight Density = 0.281 lb/in2 g = 386 in/sec2

Tested Features

Sources

LARSA 4D
Thomson, W.T., "Vibration Theory and Application," Prentice-Hall, Inc., Englewood Cliffs, N.Y., 2nd Printing, 1965, p.18.
Swanson Analysis Systems, Inc., "ANSYS Verification Manual".

Results Comparison

App Link:

https://openbrim.org/objid5prhn76b4bkpo2y9l29wc.project

Library Link:

https://openbrim.org/objid84jl4pxsn9jaol09lns71c.libobj

Model	Output Parameter	OpenBrIM	LARSA	Thomson	Swanson	OpenBrIM vs Larsa
Beam	f1(hz)	28.76	28.76	28.77	28.77	1e-3%

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