Built-up girder

A built-up girder is a primary structural member fabricated by welding plate elements, a web plate with a welded face plate or flange, rather than rolled as a single section, used where a member exceeds the size of available rolled shapes. In hull structure the built-up plate girder forms deck girders, bottom side girders, and the webs of transverse and longitudinal primary members. The web carries shear, the flange carries the bending stress at the extreme fiber, and the section modulus is sized to the class-rule bending moment. Stiffeners and tripping brackets are added to the web to prevent buckling under shear and compression.