N03: Beam on an Elastic Soil Foundation

Owned by Gokhan Alkan (Unlicensed)
Last updated: Mar 11, 2019

A 30 inch long beam rests on an elastic foundation. The beam is 3 inches wide and 1 inch deep. The soil is active in compression only. The foundation modulus is 5000 lb/cubic inch. A concentrated load of 8000 lbs is applied at the midspan of the beam.

Determine the midspan displacement and the contact length of the beam.


The material and section property data of the beam are:

Modulus of Elasticity = 30,000,000 lb/in2
Poisson's Ratio = 0.00
Izz = 0.25 in4
A = 3 in2

The model has beam and compression-only foundation spring elements. Due to symmetry, only one half of the structure is modeled.

The beam is divided into 10 equal length beam elements. The foundation is modeled using the compression-only foundation spring elements. The spring constant (K) is taken as foundation modulus times the beam width times the spacing between the springs.

K = (Foundation Modulus) x Contact Area
K = 5000 x 3 x 1.5
K = 22,500 lb/in.





Tested Features

Reference

  • Faten F. Mahmoud, N.J. Slamon and W.R. Marks, "A Direct Automated Procedure for Frictionless Contact Problems", International Journal of Numerical Methods Eng., 18 (1982), pp. 245-257.



Sources

  • M. Heteyni, "Beams on Elastic Foundation", University of Michigan Press, Ann Arbor, Michigan, 1967.
  • NISA, Verification Problems Manual, EMRC, 1990
  • LARSA 4D