When new high mast light poles at the Port of Oakland's Berths 55–56 yard began moving significantly in relatively low, commonly occurring winds, Liftech's analysis showed that a small amount of damping would solve the problem. The fix, fiber-reinforced elastomeric dampers at the pole base plates, was practical and low cost to implement on existing and future poles.
In the late 1990s, very tall high mast lighting was installed at the Port of Oakland for the new Berths 55–56 yard. The taller light poles reduced the number of poles required, saving valuable yard space. In the poles' 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, however, it was discovered that the poles' second mode of vibration was a significant problem. Vortex shedding caused resonance conditions and significant movement at relatively low, 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. They provided enough stiffness to keep the lights plumb, enough strength to withstand 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 both existing and future light poles.
