About Damping Systems
Why structures move and why it matters
When a building, bridge or other structure is subjected to external forces—typically wind, pedestrian movement or seismic activity—it vibrates or sways. In tall buildings and on large bridges, even movement that presents no danger can make people uncomfortable. Over time, such movement can also hasten material fatigue and shorten the life of the structure.
What is a tuned mass damper (TMD)?
TMDs supplement a structure’s inherent damping – for instance, the stiffness of its structural steel – and minimize undesirable motion. A properly designed damping system can easily double or triple the inherent damping capacity of a traditionally designed structure. A TMD is typically more cost effective than other strategies for controlling unwanted motion, such as adding structural material or reorienting the building relative to prevailing winds.
How a TMD works
A TMD includes a carefully designed, heavy mass that can move – for example, swinging on a pendulum or pushing against a spring. When a structure moves in response to wind or other forces, the mass also moves; this function is passive, requiring no electricity or computer system to control it. The device simply responds to the structure’s movement according to basic physical principles.
Where have TMDs been used?
TMDs support the performance of some of the world’s most demanding structures – from the tallest skyscrapers to the longest bridges. The Motioneering team has designed and implemented dozens of advanced damping systems to help owners and designers build higher, realize their business objectives and achieve bold architectural visions.
How do we create damping systems?
Our proven process optimizes efficiency from conception to completion and delivers exceptional performance and occupant comfort over the long term.
Step 1 – Wind studies
We begin by performing virtual and/or physical testing to gain deep insight into the loads the structure will experience under a range of conditions, from normal operations to extreme weather events or large crowds. Collaboration is key: we work with structural engineers, architects and owners to ensure that the structure meets its objectives – from its design ambitions to its business goals.
Step 2 – Damping system selection
After establishing performance requirements ensure safe, comfortable conditions and sustained serviceability, we determine which damping system is best suited to the project’s needs. Considerations include the structure’s proportions, its wind environment and the scale and dimensions of the space available to house the system.
Step 3 – Detailed design and fabrication
Once we’ve determined the right overall approach, we develop a more detailed design for the damping system, establishing its mass, how it will move, and exactly how it will function inside the structure. This stage involves rigorous testing of the device’s mechanics, to ensure that it functions effectively and moves at the right frequency to mitigate the structure’s movement.
Step 4 – Installation and operation
Fabricating a machine that weighs several hundred tons and installing it at the top of a skyscraper is an engineering challenge in itself, and our team is experienced in every aspect of this process. Each damping system is designed and manufactured with a tuning range, so once it’s installed it can be tuned to the precise frequency that delivers optimal as-built performance. We also deliver a complete commissioning report and train maintenance crews to ensure the effective function of the damping system over time.