Not sure if this is the best place to ask this question but forums on this seem to be limited, can anybody explain how one would discover if a steel pole lighting structure is being effected by harmonic resonance? I do not know what tools and methods would be used, if anyone can provide some detail on that. But what I struggle to understand is if a pole structure is being effected by this, it would likely only be at certain times with the right wind speeds and possibly wind direction, so if its a case of using test instruments onsite would one have to continuously visit and test in different conditions in an attempt to strike the right one? Also I believe you can use computer software to model and discover the natural frequency of a structure, but to know if it's environment will make it resonant at that exact frequency seems difficult, does anyone know the logic behind designing against such a problem? Thanks David.