The Trump Tower currently under construction in Chicago will be the tallest building project in the United States since the completion of the Sears Tower in 1974. It will also be the tallest structural reinforced concrete building in the country when it is completed in 2009.
Concrete for the Trump Tower is state-of-the-art, starting with the 10-foot-thick mat slab which rests on 110-foot-long caissons that extend into the bedrock. SOM specified self-consolidating concrete (SCC) for the mat. The 47,000 cubic yards placed had to reach 10,000 psi compressive strength within 56 days, not exceed placement temperatures of 80° F, and not reach 170° F after placement. Also, there could be a temperature differential of no more than 40° F between the center of the mat and the outside surface in order to avoid the possibility of thermal cracking.
The floor area of the tower is set back three times along its height, requiring structural transition areas for changes in the location of columns. To provide for load transfer between columns above and below the transitions, Robert Siegel, a project engineer for McHugh Construction, Chicago, says they constructed a series of “belt walls” and transfer girders. These belt walls consist of steel reinforced column and beam grids. SOM specified 12,000 psi (at 90 days) SCC to ensure good consolidation around the relatively congested rebar.
Siegel says they are keeping to their planned construction schedule and completed the 17th floor on November 30, 2006.