For long spans or heavy loadings that exceed the capacity of standard rolled shapes, plate girders can be used. Plate girders are composed of individual steel plates that can vary in width, thickness, and grade of steel along their length to optimize the cross section. However, it is important to recognize that a minimum weight design is not always the most cost effective design. For example, it is often more economical to use a thicker web plate, rather than a thinner one with multiple transverse stiffeners, because of the reduced fabrication costs. Also, the material savings obtained from splicing flange plates may be offset by the cost of the welded splice. (See Art. 11.17.)
