Steel Boxes Carry Rail Lines

by Andre Witschi, (M.ASCE), Assoc.; Envirodyne Engrs. Inc., Chicago, IL,
Rene Amon, (F.ASCE), Prof.; Civ. Engrg. Dept., Univ. of Illinois, Chicago, IL,

Serial Information: Civil Engineering—ASCE, 1987, Vol. 57, Issue 4, Pg. 62-64

Document Type: Feature article


Steel box girders plus novel bearing details led to beautiful curved bridges carrying Chicago Transit Authority trains into its Howard Yard. During preliminary design three alternative designs were considered—through steel girders, curved steel plate girders supporting a concrete deck, and curved steel box girders supporting a concrete deck. Though not least costly, the last was chosen, because it is esthetically superior. At the ends of the two box structures crossing Chicago Avenue, the forces and motions the bearings have to handle are complex. The expansion pin bearing, thought to be a unique bearing, was developed. Because the center span is long relative to the end spans, the bearing has handle uplift forces in addition to thermal expansion and contraction, so movable vertical links and pin connections were included. To permit longitudinal movement but prevent transverse movement, a sliding rod-in-groove detail was developed.

Subject Headings: Steel decks | Steel plates | Plate girders | Curvature | Steel | Rail transportation | Steel bridges | Girder bridges | Chicago | Illinois | United States

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