Description
A 3-story building frame is shown in the figure. The mass of the frame is lumped in the girders, with values as shown, and the columns are assumed to be weightless. Also, the girders are assumed to be rigid, so that the columns in each story act as simple lateral springs with stiffness values as indicated. It is desired to calculate the resonance frequencies of the frame.
The problem is idealized as the mass-spring system shown below:
File Name
Browse to
drive letter:\Users\Public\Public
Documents\SOLIDWORKS\SOLIDWORKS
version\samples\Simulation
Examples\Verification\Frequency_15.SLDASM and open the
file.
Meshing Parameters
Use a global element size that corresponds to the leftmost position on the mesh slider. A larger element size can be used since only rigid body modes are of interest.
Modeling Hints
Artificial material densities are used to account for proper mass values (mass = volume*density). The Spring and Elastic Support connectors are used to define column stiffness values.
Results
| |
Theory |
SOLIDWORKS Simulation |
| First Mode (rad/sec) |
14.5 |
14.3 |
| Second Mode (rad/sec) |
31.1 |
31.2 |
| Third Mode (rad/sec) |
46.1 |
46.6 |
Reference
Ray W. Clough, J. Penzien, "Dynamics of Structures," McGraw-Hill Book Company, 1975, Chapter 12, pp 177.