Nonlinear Analysis Research

To study the effects of hourglassing parameters particular to LS-DYNA, a finite element model was generated and analyzed for static loading conditions. A number of internal variables within the program were determined to be likely key players in the hourglassing behavior of the model and were varied to determine their effects on the model as a whole, as well as the individual materials of which the model was composed. Results indicate that the application of traction loads as seismic input more closely matches the target surface motions. A comparison of maximum and minimum values of velocity and acceleration as well as frequency content leads to this conclusion. The comparison of ASI values indicates that any structure modeled on the surface of the foundation would be subject to excess energy during a seismic analysis.