Sags & Tensions of Span Attachments

After you have your starting point on the Initial Curve you must then apply all reasonable load conditions to the wire or cable to find the one that stretches it the highest on that curve. This helps to define the Final after Load curve. You also need to determine where on the Initial Curve the average everyday "No Load" at average day temperature (e.g. 10C) condition would lie. You need to specifically calculate the stress of this condition. For each constant span length and elevation differences in a line, you can solve for the applicable strain value after Creep from the Creep polynomials. Following this stress and new strain value down to zero strain using the slope of the Final Modulus of Elasticity will determine the amount of permanent stretch due to creep and the Final after Creep Curve.

Wires/cables with different material type for inner and outer layers will need to be calculated in a coordinated way. Once these three curves are well defined, all other load conditions required by code (plus other reasonable or desired ones) should be tested and made available. Then for each code requirement, as mentioned before, the results from all three curves must be considered under all reasonable load conditions.

As mentioned previously, maximum sag and maximum tension will not be from the same load case. Each span will need to be calculated separately to uniquely consider the span length and elevation differences. Other code requirements could require different load case results from the maximum sag or maximum tension ones.

To support sags and tensions, but also a multitude of clearance/separation tests in 3D, Quick Pole utilizes an advanced Catenary Cable Element. This speeds up structural calculations by providing both support loads for complicated weather loads, plus an accurate model of the stiffness the span attachments provide to the structure.