FEM Concrete/tr

This page collects some interesting topics in the regard of concrete structures:
 * https://forum.freecadweb.org/viewtopic.php?f=18&t=28635
 * https://forum.freecadweb.org/viewtopic.php?f=18&t=28821
 * https://forum.freecadweb.org/viewtopic.php?f=18&t=30697
 * https://forum.freecadweb.org/viewtopic.php?f=18&t=30286
 * https://forum.freecadweb.org/viewtopic.php?f=18&t=29930
 * https://forum.freecadweb.org/viewtopic.php?f=18&t=29381