Get FinancingPotain MR 415 & MR 418 Build 43-Story One Congress Office Tower Using Internal Climbing Configuration
One Congress is a 1-million-square-foot, 43-story office tower in construction on Boston’s North End, and 16 floors will be ready for occupancy in 2023 thanks to the creative use of Potain’s MR 415 and MR 418 luffing-jib tower cranes.
“We were approached by John Moriarty Associates, the main contractor, to devise a plan that would allow them to start leasing floors six through 25 before the rest of the structure was complete,” says Cori Amadon, vice president of crane provider James F. Stearns. “That meant we had to rethink the original plan of tying in tower cranes to the building’s outside perimeter and come up with an interior climbing program instead.”
Climbing Tower Cranes In A Confined Space
Potain’s MR 415 and MR 418 both have 26.5-ton (24-metric-ton) lifting capacities and bases that are interchangeable with those of Potain’s MD and MDT cranes. This compatibility increases installation options for internal and external climbing configurations. Prior to the construction of One Congress, the contractor also expressed desire for a spacious working platform, and Potain luffing mechanisms and hoists were critical to saving space and pulling beams into place without taking up a large area on the working platform. The use of smaller, lighter tower cranes like the MR 415 and MR 418 also provided the project with cost savings.
“By reducing the loads that are imposed, they give you the flexibility to come up with a different type of support system that’s not as cumbersome as would be needed to support a larger tower crane,” Amadon says. “You can get great results working with an MR 608 (35.3 t/32 mt maximum capacity) from the perimeter, but if you put a 24-tonne-capacity MR 418 into the core of a building with a shorter boom, you can pretty much get the same benefit.”
Working With The MR 415
The MR 418 was installed on the western side to help with construction, including placing glass. The MR 415 was initially installed as a freestanding crane with just under 197 feet (60 meters) of mast and a matching jib length. But once the climbing frame was installed and the building erected to the 15th floor, the project progressed to phase two, where the MR 415’s mast was extended to 246 ft (75 m) and the jib was shortened to 131 ft (40 m) to erect the building to the 22nd floor. During the next two phases, the MR 415 would begin to climb the structure with the help of a diving board (support frame), letting the crane raise 90 ft (27.4 m) with each stage. Additional diving boards were added to the structure for support, including on levels 32 and 39, leading to the last phase where the MR 415 climbed 88 ft (26.8 m). Both tower cranes are now removed, opening up floors six to 25 for finishing work, while construction continues above.
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Source: Manitowoc