Wave propagation and Explicit dynamic analysis with OpenSees

[JoseLeo]

Has anyone made some explicit dynamic analysis with Opensees such as impact modeling and wave propagation?

I'm trying to simulate impulse echo test on a pile by applying a short impact loading at the top at very small duration (0.00008 s) and studying acceleration/velocity reflections at the top due to shaft constructions defects below.

Since solid models with fine mesh is too complex in Opensees, I tried to use an elastic 1D pile-soil by the beam on winkler foundation model (T-z and Q-z springs).

The expected time to get the reflection response from the bottom of the pile is t = 2L/C, where L=pile length and C=pile material wave velocity = sqrt(E/rho).

With the 1D pile-soil model, I just got inertial acceleration response at the top with no reflection from the bottom (wave propagation).

Any comments and suggestions are mostly welcome.

Thanks.