2-D finite element analysis of singly curved prestressed concrete shells

Singly curved or doubly curved shells, most commonly used in large span structures, are analyzed using flat plate/shell/plate-shell. Depending on their structural actions and stresses generated, sometimes they are also prestressed. If the prestressing is in a direction where the curvature of the shell is negligible or zero, the shell structure could be analyzed using surface elements (e.g. cylindrical shells prestressed longitudinally). If the prestressing is in a direction where the structural element has a curvature (e.g. cylindrical shells prestressed along the curved axis), it introduces circumferential forces and hence may introduce stress gradients in direction normal to the curved axis viz., in the thickness direction, which cannot be idealised using surface elements. Analysis of such shells using ADINA code is presented in this paper. The results show that for a prestressing cable placed somewhere within the thickness of the shell and sufficiently away from the boundaries, the variation of normal radial stress changes from tension above the cable profile to compression below the cable profile, clearly indicating the existence of radial tension. The magnitude of the radial tension is influenced by the parameters like radius, semi-central angle, rise of the shell and thickness. The radial stress varies inversely with radius and directly with rise, while change in thickness and semi-central angle do not affect its behaviour at the apex.