In the late 1990s, very tall high mast lighting was installed at the Port of Oakland for the new Berths 55–56 yard. The tall light poles reduced the number required, saving valuable yard space. In their design, the primary mode of vibration was analyzed, and it was determined that wind induced vibration from vortex shedding during probable winds would not be a problem.
Soon after installation, it was discovered that the light pole second mode of vibration was a significant problem with vortex shedding, experiencing resonance conditions and significant movement at relatively low and commonly occurring winds.
Liftech’s analysis indicated that a small amount of damping would mitigate this unacceptable vibration.
Fiber reinforced elastomeric dampers were installed on both sides of the light pole base plates that provided enough stiffness to keep the lights plumb, enough strength to not fail under the combined pole and lighting weight and storm wind moment, and enough damping to solve the problem. This innovative method was practical and low cost to implement on existing and future light poles.
