I assume first off here you are talking about prestressed concrete beams, no?

About in this case is said of the ends of the beam, where stresses are concentrated under the anchorage head, requiring lots of special reinforcement.

Which of course means that - if properly designed - there is little risk of buckling. So maybe we have to look further.

Maybe then they are referring to the panel/section of beam (panel/section length undefined) beyond the about section.

Or if a steel girder, then just "end panel" I presume, since for steel girders about would not have the same "reinforcement/stress" notion, even if stresses there will be different from those more centrally (bearing point inducing different forces in the beam).

You had a question previously about rib reinforcement on panneaux of steel beams, and IIRC "panel" was found to be the right word, so I assume "panel" works here too.

It needn't be the abutment panel. In a multispan bridge you'll have only two abutment panels but twice the number of end panels as there are intermediate piers.

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Note added at 1 hr (2009-11-07 12:38:05 GMT)
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This bridge is a very old example of a pin-connected Pratt through truss, ... which include replacement of one floor beam, END PANEL points reinforced, ...
www.historicbridges.org/newjersey/stanton/index.htm

BRIDGE END PANEL, BR165 ... Concrete Post and Beam Bridge Rail .... BRIDGE 400 - REINFORCED PRESTRESSED SLABS AND BOX BEAMS ...
www.oregon.gov/ODOT/HWY/.../bridge_drawings.shtml

Dowel bar for bridge END PANEL, see dwg. BR165. ...
ftp://ftp.odot.state.or.us/techserv/roadway/web.../bridge/.....

Mr. G.L. Vose, in his admirable work on R.R. Construction, observes very truly that "The braces, at the end of a long span, may be nearer the vertical than those near the centre, as they have more work to do. If the END PANEL be made twice as high as long, and the centre panel square, the intermediates varying as their distance from the end, a good architectural effect is produced."
http://infomotions.com/etexts/gutenberg/dirs/1/4/8/7/14873/1...

The principal diagonals and END PANEL hangers consist of needle-headed or loop ... All floor beams are perpendicular to the bridge centerline with the ...
www.historicbridges.org/newjersey/.../index.htm