Guyed Structure Response
The focus of these tests are to ensure that the combined models of both the pole and the supporting guying components work together in a consistent way to provide an accurate overall response. Individually the models may behave as expected, but when combined additional consistency constraints are demanded in order for them to work together properly.
As hinted in other sections, the amount that the pole or the guying components are permitted to deflect for a given amount of load is a critical determining factor for how much load each will carry. With respect to the law of diminishing returns, thicker poles or thicker guy wires will generally attract higher loads due to the fact that they are more "stiff" and have more resistance to deflection and stretch. This is the reason that the entire structure (poles plus guying components) must be solved as one unit and not independently.
Another important aspect to consider is that all guying must be applied to the SIDE of the pole. It is not possible to actually or effectively guy at the very center of the pole. The vertical load applied to the side of the pole from guying creates bending moments, which are additional loads which must be considered. When more than one guying component is attached to the pole in the same direction, these guy-created bending moments can affect the sharing of the loads between them.
To fairly evaluate any software tool, the main aspect to consider in the testing is whether the loads are accurately shared between the pole and the guying. This includes along the length of the pole and moments in addition to just forces. While the specific tests should evaluate different heights of both load and guying attachments, multiple guying scenarios should also be included.
The focus of this category of tests is to confirm that the basic pole model with the addition of guying elements behaves as expected. It is important to validate that the pole and the guys share the loads in ways that are consistent with an established baseline. The model should not produce different results when loads and guys are placed at different angles. The use of strong and weak poles with guys attached close and far away from the loads, plus multiple guy scenarios, is the focus of these tests. To simulate stronger poles, tests are performed at lower levels of the pole where the pole is thicker.
The following tests are suggested:
- Use a 40ft class 4 pole. Species to be Red Pine. Use NESC derived pole dimensions and Modulus of Elasticity.
- Apply a 10000N load at 2 feet from the top of the pole (9.75m).
- Place a 3/8" Grade 160 (or HS grade) guy wire at the load point to an anchor with a lead of 4 meters
- Measure deflection, forces, moments and fiber stresses at the guy location.
- Repeat the above test similating an overhead span guy of 40 meters with no effective vertical elevation changes.
- Repeat the above tests with the guy attachment lowered to 5 meters
- Repeat the above test with the load and guy attachment points reversed.
- Repeat the above test with the load and guy attachment points both at 5 meters high.
- Repeat all above tests with an additional same guy attachment at 7.0 meters high.
- Repeat steps 1 to 6 with the load and guying rotated by 90 degrees to prove that the models are directionally insensitive.
- No wind or storm loads
- This is a Linear Analysis with loads applied without additional load factors applied. If non-factored loads are not possible, divide the proposed load by the load factor before it is applied to the pole.