United States Department of Transportation
i
Development of guidelines for transportation of prestressed concrete girders.
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2011-11-01
[PDF-216.98 KB]
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Alternative Title:Research project capsule;10-5st;
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Abstract:"Prestressed concrete girders are an economical superstructure system for bridges. With the
advent of higher strength concretes and more effi cient cross sections, the use of long span (>100
ft.) prestressed girders are now specifi ed. Such long span girders require special consideration
during manufacturing, transporting, handling, and erecting. Many forces associated with
construction of a precast concrete girder are well understood – less, however, is known about
the forces a girder is subjected to during transport. While girders are designed for strong axis
loadings and can readily accommodate such loading during transport, they are typically braced in
service and may have inadequate resistance to lateral or lateral-torsional load eff ects. As a result,
girders have arrived on job sites exhibiting cracks indicative of weak axis bending or torsion. In
other instances, trucks transporting girders have rolled as the girders laterally buckled. These
transportation problems can delay construction while the girders are repaired or replaced and
lead to a reduced service life as moisture and chlorides infi ltrate unrepaired cracked girders.
The Louisiana Department of Transportation and Development (LADOTD) has observed these
transportation problems with prestressed concrete girders. Building on research into girder
stability design by Laszlo and Imper and estimations of transportation stresses by Mast, LADOTD
recently instrumented two 150-ft. long prestressed bulb-tees during transport in an eff ort to
assess the forces on the girders. Transportation of these instrumented girders resulted in some
weak axis cracking."
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