[en] Within a German PRCV-program at the Institut fuer Massivbau of the Technical University of Munich tests are made in order to provide the information necessary for an analytical modelling of thick concrete cylinders. In 1976 the series was started with 2 tests on large size unreinforced concrete rings (inner diameter 10.9 cm, outer diameter 36.5 cm resp. 62.5 cm, thickness 10 cm) under inside pressure. The loading was electronically controlled under the condition of a linear increase of the mean strain rate (0.0002/hour). This method provides detailed information on the deformation behavior during rupture of the specimen. The main strain was measured at the inner side of the ring by 8 inductive gages. To obtain the information necessary for a finite element analysis the specimen was subdivided by a triangular net for which all tangential strains have been measured by inductive gages, whereas all radial and diagonal strains have been measured using strain gages. Additionally the increase of the ring diameter has been recorded. (Auth.)