Bespoke Spring Mount Bearings for Helipad, Stockholm Hospital – Sweden
Mason UK worked on the new Karolinska Hospital in Stockholm, Sweden where the roof serves as a landing pad for two helicopters. To prevent pulsations from the rotor blades affecting the sensitive equipment in this medical research facility the entire roof structure is isolated by our bespoke spring mounts.
The spring isolators were designed to provide a natural frequency of 2Hz, offering high isolation efficiency against the 24Hz rotor pulsations. The building features highly sensitive research equipment which would likely be affected by such energy, even following dissipation through the building structure.
Detailed Design
It was important to work closely with the structural engineering team on this project. The springs were integrated in the columns at the steelwork fabricator’s premises, meaning minimal interruption on the actual site. The column heads featured telescoping stanchions which bore the weight of the building during construction, providing a static platform.
When the construction was completed, Mason UK used the load transfer method to move weight from the stanchions to the spring mounts. This enabled precise control of spring compression and only negligible roof movement. This method significantly reduced the risk of isolating such a large structure. In addition to that, the Mason springs were designed to tolerate variation in the final weight. The spring compression was simply changed to suit the actual loading.
Successful Installation
The process of floating this large structure was complex but successful. Isolating the helipad rather than the sensitive equipment allowed for a much more flexible space and negated the need for large inertial blocks in each sensitive area.
Products Related to Article
Restrained Spring Mounts
Restrained Spring Mounts are spring mounts supplied with a housing which restricts spring travel. This is useful when equipment is subject to wind loading or changes weight during maintenance.
Elastomeric Isolation Bearings
Elastomeric bearings can be made from a variety of materials and are very effective against most medium to high frequency vibration sources. The material choice depends on the environment, but natural rubber is the most common choice due to its low dynamic stiffness.
Structural Isolation Bearings
Building isolation bearings are used to isolate entire buildings or elements such as walls, floor plates, or columns. Bearings are normally bespoke, designed to accept the specific loads and have the correct isolation characteristics.
Spring Isolation Bearings
Spring bearings are used to isolate against low frequency vibration sources and impact. They can be made using single or multiple springs and low natural frequencies of less than 2.0Hz can be achieved.
