The inclusion of New York’s first viscous damping system on a 40-storey office tower in Manhattan has saved the client, Boston Properties, $5 million by reducing steel requirements by 10 per cent.
The building, at 250 West 55th Street, was designed by architect Skidmore Owings and Merrill LLP (SOM) and engineers Arup. It includes office space, a green roof, two podium levels and two basement levels.
The incorporation of the innovative viscous damping system into the outrigger and belt truss at the crown of the building reduces the building’s motion during wind storms, enabling the steel tonnage to be significantly reduced, resulting in the excellent cost savings.
Fluid viscous dampers for structures are similar in action to the shock absorber on a car but operate at a much higher force level. Fluid viscous dampers can be incorporated into both new buildings and existing structures. As they are relatively small and inconspicuous, they can be built into a structure without compromising its appearance. This is especially useful in the refurbishment of historically significant buildings. They can also be added without significant structural modification in most cases.
Seven small viscous dampers integrated into the mechanical space at the top of this Manhattan building eliminated the need for a tuned-mass damper, which would have taken up valuable space and reduced the lettable area of the development.
Arup used Building Information Modelling (BIM) to deliver the design, pushing the technology even further by passing the design model to the fabricator and then reviewing the detailed fabrication model in 3D, speeding the review process and dramatically reducing coordination problems.
“Arup’s engineering innovations helped us save $5 million and gave us more usable space per floor. The degree of coordination achieved with the Revit and Tekla models was extremely thorough evidenced by the low number of RFI’s received for the entire steel fabrication and erection process,” said Robert Schubert, senior vice president of construction at Boston Properties.
Borrowing from SOM’s classic designs for Lever House and Chase Manhattan Bank, this building begins with a strong, clear form that derives directly from its program.
“Changing sky conditions and the surrounding Manhattan context interact with the building’s exterior skin, result in an ever-changing visual phenomenon. This changing composition is achieved by an assemblage of semi-reflective, low-iron vision glass and reflective vertical fins which together, add visual depth to the surface of the building and provide shifting readings depending on viewer perspective and daylight conditions,” SOM said on its website.
The office tower is slated for occupancy in early 2014, having just reached substantial completion of the structure and envelope.