Target Damping
Ratio
Actual Damping
Ratio After Install
Problem
A major Canadian telecom operator had noticed significant vibration on a monopole tower located in Calgary, Alberta. The tower was experiencing vortex shedding, a phenomenon where wind flowing past a tall, cylindrical structure creates alternating low-pressure vortices, causing the structure to vibrate. These oscillating forces can lead to fatigue, structural damage, or even failure if they align with the tower’s natural frequency.
Varcon assessed that the tower needed a 3.2% reduction in vibration, a not insignificant intervention. Without addressing these vibrations, the tower faced additional stress and was likely to wear and fail more quickly, requiring increased maintenance and incurring added costs for its owner.
An additional challenge in this case was the presence of an access hatch at the top of the tower, limiting space for the installation of countermeasures to address vibration.
“Liquid dampers empower tower owners to reduce vibration and wear on their assets. The result is greater structural longevity, maintenance savings, reduced downtime, and risk mitigation.”
Kevin Scherbatiuk, Ph.D., P.Eng.
Varcon Structural Engineer
Solution
The Varcon team in Alberta designed, fabricated and installed a liquid damper on the tower to mitigate against the vibrations. Liquid dampers, also known as tuned liquid dampers (TLDs), use the movement of liquid within a sealed chamber to counteract structural vibrations. In tower engineering, they are sometimes installed as mounted components to absorb wind-induced oscillations, especially on tall, slender structures like monopoles. Their effectiveness in damping low-frequency vibrations makes them valuable for extending tower lifespan and minimizing maintenance related to dynamic wind loads.
The Varcon team designed a pair of liquid dampers, instead of a single unit, to accommodate the access hatch at the top of the tower. This split the damping power in two, making the footprint more manageable for the site, without compromising the damping power of the solution.
Outcome
The tower not only achieved the 3.2% target, but exceeded it. Ultimately, a 3.74% improvement was delivered by the twin liquid dampers. This figure was confirmed in a post-installation assessment by the Varcon team. Additionally, our client was not forced to make changes to the access hatch or the tower design (beyond installing the dampers) which represents a major savings.
Dampers are a cost-effective, low-disruption solution that protects telecom towers from vibrational damage, reduces lifecycle costs, and supports the longevity and reliability of critical communications infrastructure. As environmental forces intensify and towers age, damper technology is shifting from optional to essential.
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