How does vibration affect industrial light towers? This article covers types of wind-based and environmental factors that contribute to vibration for poles supporting lights.
First and Second Mode Vibration
Vibration experienced by poles and masts is categorized under first mode and second mode. First mode refers to infrequent, but powerful gusts of wind encountered by the mast. During such occurrences, most of the movement or swaying is happening at the top of the pole. Compared to second mode, this type does not always contribute to damage, since most units are designed to address first mode vibration. Signs of first mode vibration includes the movement of light beams from side to side.
During second mode vibration, most of the shaking is happening at the center, foundational components of the mast. Winds are consistent and frequent, sometimes reaching 35 mph. Persistent pressure-shifting experienced by the unit results in stress and fatigue. Second mode vibration is difficult to detect because the equipment on top of the mast is unfazed by the shaking. Operators can detect such occurrences by listening for a humming sound from the pole.
Factors to Consider (Height and Location)
There are several factors that can either contribute to or reduce vibration for industrial light towers on construction sites. Masts taller than 25 feet are more prone to experiencing wind-based vibration. Furthermore, the load of the pole (when mounting equipment at the top) should never be exceeded, as it could cause unnecessary strain on the structure.
Lastly, the location of deployment could dictate the amount and type of vibration encountered by the light mast. Construction sites, airports, parking lots and bridges are locations that experience massive amounts of vibration on a regular basis, from moving cars and airplanes. Large fields, as well as high and low elevation areas that are unprotected by crippling winds are also prone to high-level vibration.