Modelling a H frame double pole

Distribution and transmission lines may be supported by an H frame double pole arrangement.

This example includes wire bracing between the poles. Poles may be unbraced or have a variety of arrangements of bracing.

If you need to assess an existing pole you probably can’t accurately determine if the bracing is effective. A conservative approach is to consider the poles as unbraced.

The images above show output from a simple finite element analysis, modelling the poles as beams with a load applied at the tip. The single pole on the right has twice the strength of each single pole on the left. The bracing on the left model is hinged, causing the poles to deflect together but providing no strength. The deflection is the same for the two models.

Therefore it is reasonable to model unbraced poles in Poles ‘n’ Wires as a single pole with twice the strength of the single pole, if the two poles are the same size and strength. (If the poles differ you may want to use the strength of the smaller pole.) If you need to include wind loading on the pole you will need to work out the average equivalent diameter—don’t just double the diameter.