This paper presents results of an experimental study and a literature survey of the reinforcement detailing in concrete frame corners subjected to closing or opening moment. A total of 11 full-scale specimens (8 for closing moment and 3 for opening moment) were tested to evaluate whether a new reinforcement detailing using reinforcement loops lap-spliced within the corner is appropriate for use in Swedish civil defense shelters. In combination with nonlinear finite element analysis, it was found that the new detailing was sufficient for use. It is also shown that the use of inclined bars, commonly accepted in opening frame corners, may not be as effective as previously believed.