Located at 250 South Street in New York City, a new tower, known as One Manhattan Square, is currently being built on the site of a former Pathmark grocery store. When complete, the 80-story building will stand out significantly within the context of the neighborhood, since the next highest structure in the immediate area is the 330-foot-high Manhattan Bridge.
The Lower East Side has traditionally been an enormous low-rise residential area along the East River. This new, modern, glass tower will be located on the edge of the New York Harbor and provide stunning river and skyline views, with beautiful apartments surrounded by lush private gardens and more than 100,000 square feet of indoor and outdoor amenities.
This structure presents many design and site challenges for the formwork. To begin with, it is necessary to form a nonsymmetrical V-column 70 feet in height and cast in just three lifts. The cantilevered fifth-floor slab calls for 36-inch concrete beams, 70 feet high. Also, it is necessary to form the 70-foot column without any deviation. The project is designed with unusual triangular-shaped geometry, which is a challenge for any formwork. Additionally, the location has proven to be difficult — there is limited space onsite in downtown Manhattan. And, as on any jobsite, there must be an emphasis on safety.
“When we estimated this project, we went out to several form and scaffold suppliers for suggestions and solutions. We knew how we were going to build the concrete formwork and were looking for a system to provide the support of both the sloping columns and deck above. After interviewing three form/scaffold design firms, it was Doka that provided the best and most efficient solution to solving this problem and providing the engineering that we required,” says Robert Mannino, senior estimator and executive project manager, Pinnacle Industries.
Maximum safety is achieved on this project by using Doka’s Staxo safety tie-off points and slip-resistant ladders, which are integrated in every frame. The formwork’s high leg load capacity (of up to 22.5 kip per leg), combined with the optimum adaptability to different layouts, floor shapes and loads, including precise height adjustment, aids in project success. Additionally, the pallets used for the Staxo frames make it easy to organize the frames. When the frames are in use, the pallets stack and may be stored neatly in a small organized area. The Staxo system is being used to support the fifth-floor cantilever.
Doka also is providing working platforms and support for the full height of column forms. Doka’s ability to form the column at full height, but yet being able to set rebar and pour in manageable lifts, have made accuracy and the high-quality results desired possible. Using Frami Xlife, Doka was able to form the columns in the full 70-foot height, but place the concrete in three lifts. To work with the triangular geometry, the column was formed on three sides with Frami Xlife, which allowed the contractor to pour the columns in manageable lifts, but still would ensure an accurate and precise outcome. Additionally, shoring doesn’t typically take lateral load, but Doka designed it so it could stand the full 70 feet and support the formwork, enabling the column to be plumbed and formed perfectly straight. On the job, using Frami Xlife panels allows flexible and fast forming of the 5x3-foot columns with minimal ties required.
An unexpected challenge was that the hoist towers were erected early. This meant that when Doka was erecting their formwork, they needed to work around the hoist towers that were already in place.
The 80-story One Manhattan Square is still in process, with a projected completion date of 2019.