Overview

Mahir Sen, P.E.

Manager, Structures Department
Michael Baker Jr., Inc.
Princeton, New Jersey

Alfred Hedefine, P.E.

Former President
Parsons Brinckerhoff Quade & Douglas Inc.
New York, New York

John Swindlehurst, P.E.
Former Senior Professional Associate
Parsons Brinckerhoff Quade & Douglas Inc.
Newark, New Jersey

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 highway-bridge 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.