What should designers consider when choosing girder flange sizes?
Fabricators combine plates and nest them to realize economy and minimize scrap. Flange plates are flame cut to width and several items need to be considered in design:
- Avoid transition in flange width. Fabricators prefer to weld slabs and then strip. This simple request eliminates over 50% of the crane moves to prepare flanges. It also economizes non-destructive testing costs by eliminating many run-off tabs in the weld process, tab removal, and grinding operations.
- Curved flanges can be cut to a common radii and heat adjusted to final shape after the girders are built.
- The center flange plate of a girder should be a common length across the bridge width.
- A709 Grade 50 and HPS 70 steel is readily available in 1/8" increments, but consider using 1/4" increments to achieve economy through greater uniformity in flange cross-section.