This study presents a description of the mechanics of forming dough pieces into cylindrical (cylinder-like) shapes. Based on the configuration of forming, the movement of the formed piece and its surface deformations were described. Kinematic relationships concerning the dough piece material as a rheological fluid were formulated. Next, the relationships coupling the kinematic quantities present with both descriptions were determined. The components of the deformation rate tensor, presented in the assumed forming configuration (cylindrical coordinate system), describe the velocity distribution on the surface of dough piece being formed and deformed. The determined kinematic quantities and their interrelations may be used to describe the process of forming dough pieces into cylindrical shapes.
The analysis was focused on three post-tensioned slab bridges, constructed in 1950s. Two of them function normally and will probably achieve the life span of 100 years required by the relevant regulations. The third one will likely be demolished soon and replaced with a new reinforced concrete frame bridge. To its degradation contributed the faulty diagnosis of its technical condition during its periodic technical inspections. The introduction briefly characterises the development of the prestressed structure theories reviewing papers on concrete rheology and monographs looking into prestressing. The paper is based on the existing fragments of the technical design documents concerning the bridges in question. The bridges were designed by Polish civil engineers.