Steel beam and girder bridges are often the most economical type of framing. Contemporary capabilities for extending beam construction to longer and longer spans safely and economically can be traced to the introduction of steel and the availability, in the early part of the twentieth century, of standardized rolled beams. By the late thirties, after wide-flange shapes became generally available, highway stringer bridges were erected with simply supported, wide-flange beams on spans up to about 110 ft. Riveted plate girders were used for highwaybridge spans up to about 150 ft. In the fifties, girder spans were extended to 300 ft by taking  advantage of welding, continuity, and composite construction. And in the sixties, spans two and three times as long became economically feasible with the use of high-strength steels and box girders, or orthotropic-plate construction, or stayed girders. Thus, now, engineers, as a matter of common practice, design girder bridges for medium and long spans as well as for short spans.

2.1. Characteristics of Beam Bridges
2.2. Example Allowable-Stress Design of Composite, Rolled-Beam Stringer Bridge
2.3. Characteristics of Plate-Girder Stringer Bridges
2.4. Example Allowable-Stress Design of Composite, Plate-Girder Bridge
2.5. Example Load-Factor Design of Composite Plate-Girder Bridge
2.6. Characteristics of Curved Girder Bridges
2.7. Example Allowable-Stress Design of Curved Stringer Bridge
2.8. Deck Plate-Girder Bridges with Floorbeams
2.9. Example Allowable-Stress Design of Deck Plate-Girder Bridge with Floorbeams
2.10. Through Plate-Girder Bridges with Floorbeams
2.11. Example Allowable-Stress Design of a Through Plate-Girder Bridge
2.12. Composite Box-Girder Bridges
2.13. Example Allowable-Stress Design of a Composite Box-Girder Bridge
2.14. Orthotropic-Plate Girder Bridges
2.15. Example Design of an Orthotropic-Plate Box-Girder Bridge
2.16. Continuous-Beam Bridges
2.17. Allowable-Stress Design of Bridge with Continuous, Composite Stringers
2.18. Example Load and Resistance Factor Design (LRFD) of Composite Plate-Girder Bridge