The plastoelastic deformation of a structure consisting of a plate stiffened with ribs, was considered. The rib lower ends were made fast on an undeformable support. The structure in a whole was uniformly heated and then cooled. The problem was solved in the one-dimensional approximation. At that the structure was represented as a system of horizontal and vertical bars. The analysis was made for the cases of elastic and plastoelastic deformations. The size of plastic zones and the moments in the place of bar and pillar fixation depending on the load, were calculated. It was revealed that the zone size increased with the load growth. The bending of a horizontal bar was also calculated.