Damping Explained: A range of possibilities

Updated: Sep 3, 2021



As buildings get taller, they often require robust damping solutions to mitigate wind-induced movement. Project engineers have multiple options to reduce building movement using supplemental damping systems. Understanding the benefits of each system will help you determine which type of damper will work best with your project.


A traditional approach: distributed damping Distributed damping is when viscous dampers are positioned throughout a building in different areas and on every floor. This is a mature technology that works well for buildings with shear-type deformation located in seismically-active areas. However, it’s better suited for low-rise buildings such as manufacturing facilities as opposed to high-rise structures. As buildings become taller, distributed damping can occupy too much space or become too expensive.


What is a tuned mass damper (TMD)?


Fortunately, damping technology continues to advance and today tuned mass dampers are more economical and compact than ever before, and easier to maintain than distributed damping systems. Simply put, a TMD is a heavy piece of ballast placed at the location where the building moves the most, usually the top. The TMD cancels out the building’s movement by moving in opposite phase.


Tuned mass dampers are an effective solution when space is at a premium. Although TMDs can be expensive, they help save valuable floorspace elsewhere in the building. A compact TMD at the top of your building leaves more room for amenities and residential and/or commercial units on lower floors.


What is a tuned sloshing damper (TSD)?


If space is not at a high premium, a tuned sloshing damper can be a viable option. A TSD is a large tank of water or other liquid that moves around to offset the building’s movements.

Although a TSD typically requires more space than a TMD (because it is filled with liquid instead of metal) it can be a more economical option. This is particularly true when there is flexibility in repositioning top-of-building elements such as HVAC, amenities, and fire suppression.


In addition, TSDs can also have other practical functions in addition to damping. Some jurisdictions, for instance, require rooftop fire suppression systems. Often, this involves a large volume of water located on or near the roof. It makes sense to design this tank of water to also function as a damper.


What is a Hummingbird damper?


A Hummingbird damper is a variation on the tuned sloshing damper. The liquid is held in long cylinders, instead of in a large tank as traditionally found in TSDs. Hummingbird dampers are therefore modular and do not need to be positioned immediately next to each other, which means they can be positioned almost anywhere within the top of the building.


Hummingbirds are also an effective retrofit option. For example, a building might have been reclad and the new cladding provides less damping, requiring additional mitigation to reduce building motion. A Hummingbird damper is the best option in such situations.


What type of supplemental damping systems should I choose?


Whether you have a lot of space for a damping system and want the least expensive solution available, or you have incredibly valuable space at the top of the building and are looking for a solution that will fit within your existing design, we can work with you to identify which system best meets your needs.


Find the right damping solution for your project or check out the first video in our Damping Explained series, Chapter 1: What is Damping.

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