The Attachment Geometric Nonlinearity feature used in a Nonlinear Analysis, is responsible for changing the DIRECTION of span attachment tensions to match the deflection of the structure under analysis. This feature can make a small difference in %utilization in some cases, particularly tangent poles.
While in most cases this feature will provide a more accurate analysis of all structures, caution should be used in scenarios where several tangent poles in series are being analyzed. Since currently each structure is evaluated separately in Quick Pole while the others are assumed fixed, a tangent pole using this feature will a generate support from the fixed pole(s) that doesn't happen in reality. In reality the entire string of tangent poles will deflect from wind load in the same direction and at the same time. This means that this additional support does not happen. For this reason we always suggest turning this feature OFF for tangent poles whose adjacent poles are also tangent.
We have plans in the works to analyze each wind angle related loadcase, for all structures, at the same time. When this happens, this feature will be discontinued. For those familiar with PLSCADD, this would equate to a Level 4 analysis.
With that said, this feature was disable by accident in the last update. Please update to the latest version if you wish to use this feature. If you have further questions about this, this don't hesitate to contact us for more information.