Is the post-traumatic stress disorder limited to soldiers?

Not limited. Ptsd can occur from any kind of trauma. The severity of the trauma and duration of exposure seem to play a role in who develop ptsd . Victims of rape and other crimes may develop ptsd.
No. The fact that there are so many veterans with this disease, sometimes gives people the idea that it is a military disorder. What is necessary is that that their is a trauma or traumas that are horrific or life threatening. There are many civilian who suffer from ptsd.