As part of our continual efforts to make our Pole Analysis results accurate reflect actual pole line behaviors, we have completed the last in a series of planned Nonlinear Analysis techniques for Quick Pole. This last part was called Load Nonlinearity.
The term Nonlinear Analysis covers several different factors which can be considered to increase the accuracy of the analysis results. These were covered in detail in a previous post. The most basic and the minimum requirement for Nonlinear Analysis is what is called "P-Delta" effect. That is the consideration of vertical loads creating additional bending moments when the pole deflects under load. This is where most other Pole Line Design tools stop for capability, which is a shame.
A second Nonlinear effect that Quick Pole has had for quite some time is the nonlinear effect that guying to anchors can have on a pole as it deflects under load. National Standards of many countries already include guying assemblies of a pole to be considered as part of those structures; which would suggest that a Nonlinear Analysis of these structures would include all geometric Nonlinearities of the pole and its guying assemblies. We know of at least two popular Pole Line Design tools that claim to implement Nonlinear Analysis, but do not include this aspect.
The third Nonlinear effect that has been added today is called Attachment Load Nonlinearity. This is the nonlinear effect that all the line attachments have on the pole, as the pole deflects. This means that all line attachments are modeled as wire attachments (similar to guys) and not just as a computed force acting onto the pole like many other programs. Unbalanced tensions from line attachments will cause the pole to deflect (as before). The important Nonlinear effect added here is that the tensions/forces of the line attachments will now change as the pole deflects (in response to unbalanced forces). For instance, when the pole moves attachments in one direction will tighten (higher forces) and another may slacken (lessen forces). The determination of this effect is an iterative process of pole deflection, change in unbalanced forces acting on the pole, pole deflection changes... Based on where the attachments are attached onto the pole has an impact as well, given that the pole is more flexible closer to its top.
This last Nonlinear effect can be very significant in pole lines with unequal span lengths. If you just apply the initial assumed forces/tensions to a pole and ignore the balancing that the pole's deflections will assist with, your load analysis results will always show the pole with unrealistically high utilization percentages. You may even drive unnecessary Make Ready work.
For those people interested in experimenting with these Nonlinear effects in a more granular way, Quick Pole has provided extra analysis options in the Nonlinear category. One for Guying Nonlinearities and one for Attachment Load Nonlinearities. This is for informational and educational purposes only and is not considered a project option to be stored with the project. You can now prove that the "Ruling Span Concept" is real with Quick Pole; if you had the interest.