Stub sill assemblies

A subassembly for a railroad tank car having a tank with a generally cylindrical tank body and a convex head, the subassembly comprising:

• a center sill including a generally horizontal top member and a pair of upright side plates spaced apart laterally from each other;
• and
• a head brace having a lower margin welded to the top member of the center sill and an upper margin welded to the head of the tank,
• wherein each of the pair of upright side plates includes opposed first and second longitudinal end portions and a longitudinal central portion disposed between the first and second longitudinal end portions, the second longitudinal end portion being adjacent to the head brace and the first longitudinal end portion being spaced from the head brace relative to the second longitudinal end portion, each of the pair of upright side plates having a top surface and an opposed bottom surface, the top surface being co-planar within the longitudinal central portion and at least a substantial part of the first longitudinal end portion, the bottom surface being parallel to the top surface within the longitudinal central portion, the second longitudinal end portion, and a first portion of the first longitudinal end portion, and the bottom surface being co-planar within the longitudinal central portion, the second longitudinal end portion, and the first portion of the first longitudinal end portion,
• wherein each of the pair of upright side plates further includes opposed first and second longitudinal end surfaces that are parallel to each other, the first longitudinal end surface is within the first longitudinal end portion, and the second longitudinal end surface is within the second longitudinal end portion,
• wherein each of the pair of upright side plates further includes an inclined surface connecting the first longitudinal end surface and the bottom surface, and
• wherein the entirety of the bottom surface between the inclined surface and the first portion of the bottom surface has a shape that includes or approximates one or more radiuses of curvature.