Concrete & Masonry work on both stations.
Large tension forces on the caissons
required heavy reinforcement, which, in turn, dictated that large slump, small
aggregate concrete be used. Additional cement was required because concrete was placed underwater in the tremie method and to maintain adequate slump as
additional water was added because of the high ambient temperatures that existed during concrete placement.
Manhattan Station: Concrete ground level slab, boarding slabs and beams and four main 40’ high columns, which support the roof and station saddles. Two of these are 41” square composite concrete columns, which are designed to also support a future 32 story building above the station. |
Roosevelt Island Station: Two, 2’ thick shear walls serve as the main anchorage for track cables. An 11’-6” diameter concrete bollard, integrally formed as part of the shear wall, protrudes 1’ out from each face of the shear wall. The large uplift force on each wall due to the overturning moment is resisted by splicing tensile reinforcement to a steel base plate which is anchored to rock using pre-stressed rock anchors.
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