May 12, 2015
CHICAGO – Clark's 150 North Riverside project team has completed several milestones since breaking ground last July. To begin construction on Chicago's 16th tallest building, the team completed the city's second largest mat foundation placement pour; they also installed a Manitowoc 888 Ringer Crane, which is located within the Chicago River.
The 55-story building is nestled between the Chicago River and an existing building. Seven active railroad tracks run directly through the site and two elevated roadways border the site on the river's side. With a number of site limitations, Clark's team had to construct a 10-foot-thick mat foundation to support the tower. The team placed 3,024 cubic yards of an 8,000-pounds-per-square-inch, self-consolidating concrete mix and 750 tons of rebar to support the 755-foot-tall steel structure. The effort took 336 concrete trucks and 19 hours to complete. Sixteen rock-socketted caissons, measuring 10 feet in diameter, also comprise the foundation system of the main tower structure.
Once the foundation was complete, the team turned their focus to enclosing the active rail lines to create a public plaza. Crews will use 30-foot-tall, cast-in-place concrete walls and concrete bulb tees to cover the tracks. With no space to put a crane, and bulb tees weighing as much as 128,000 pounds, which is too heavy for tower cranes to lift, the team designed an anchoring system that would allow them to place a crane on a barge in the Chicago River.
The barge consists of 31 interlocking sections that support the two-million-pound Manitowoc 888 Ringer Crane and 800,000 pounds of matting and payload. The barge is anchored by four spuds driven into the riverbed. The crane has a 300-foot boom and a maximum capacity of 660 tons. The size of the crane will allow the team to pick up the bulb tees over the rising core and set them up to 200 feet away on the west side of the site.
The team will spend the next month placing 196 bulb tees to complete this phase of the project.