A New Dimension In Precast Prestressed Concrete Bridges For Congested Urban Areas In High Seismic Zones

A New Dimension In Precast Prestressed Concrete Bridges For Congested Urban Areas In High Seismic Zones Twin precast, pretensioned concrete bridges were recently built over Tlalpan Freeway - in one of Mexico City''s most densely populated areas. Designed for a clear span of 170 (52 m) over a major freeway, they bring a new dimension to bridges for heavy traffic urban areas in seismic zones. Each of the twin gridgees consists of three longitudinal girders with a total length of 1539 ft (469 m). Each girder comprises 13 pretensioned elements of hollow box cross section with two upper flanges. The substructure consists of cast-in-place columns supported on a foundation of casst-in-place caissons and precast, reinforced concrete piles. Seismic forces are resisted by longitudinal frames integrating columns with main support elements, and by transverse reinforced concrete beams.

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