A highly efficient vibration isolation solution was provided for a major luxury high-rise project in Manhattan, New York City to prevent vibrations from a train tunnel under the property.

The Rushmore Building on the Upper West Side of Manhattan, is a 41-storey luxury condo complex developed by real estate developer Extell as part of New York City’s largest construction project in the last 50 years. The overall project consists of 18 high-rise buildings and 7.9 million square metres of floor space.

The construction of the Rushmore presented a massive challenge as the two-towered high-rise was to be constructed directly over an AMTRAK railway tunnel. The tunnel consists of two railway lines carrying 25-ton axle loads and a planned future metro line, leading to concerns about rail-generated vibrations.

In addition to mounting a two-tower high-rise complex above a train tunnel, key challenges also included decoupling individual floors from vibrations, and meeting compliance requirements for ceiling height with smaller distance between the floors.

A developer and manufacturer of materials for vibration mitigation and isolation, Getzner Werkstoffe GmbH is also an experienced consultant in construction engineering issues related to vibration and isolation. Thanks to Getzner’s technical expertise in vibration isolation, the end result is a smart system using elastic materials, which ensure high levels of cost effectiveness, noise protection and comfort.

Getzner Werkstoffe worked with their North American partner Soundown Corporation during the 2007-2008 implementation period to develop and successfully install a suitable vibration isolation solution.

Polyurethane mats for highly efficient vibration isolation

Getzner Werkstoffe developed a completely new method for the elastic mounting of the skyscrapers. All the individual floors of the 41-storey building are elastically mounted with two storeys completely decoupled in terms of vibrations, similar to drawers that can be removed. The ground floor and mezzanine level are mounted on 9cm polyurethane Sylomer blocks, with neither of the two floors connected with the building in a fixed manner.

Sylomer mats were also used on the sides of the loadbearing columns to protect against the influence of wind. Working with the architects and structural engineers, Getzner prepared detailed load distribution plans, with loads on each of the 350 bearing points precisely determined. The ground floor was constructed using support beams with the isolation recessed in the ceiling of the first floor. The new construction method with T-beams helped minimise the built-up height.

Feedback from the general contractor

“Our project team was very impressed with the cooperation with Getzner and Soundown during the course of the planning and coordination. Both firms were extremely flexible and proactive in getting all participants involved in the project and coordinating the work together.

“Thanks to this approach, it was possible to devise an isolation system for the building, which is successfully integrated into the structure itself. Installation on-site went very smoothly and quickly, without interruptions. If vibration isolation is what you need, I would not hesitate to recommend Getzner, Soundown and Sylomer products,” says David Ridoutt, Project Manager.