Cable Analysis: Linear Static or Nonlinear Static load cases?

[psu08engr]

I’m looking for some tech support on whether to use linear or nonlinear analysis to perform simple cable analysis. I’m doing a displacement verification analysis for cable to be used in pedestrian railing. I am trying to determine the displacement effects of the cable due to an external distributed load. As of now I have modeled a simple 2 span cable supported with pins on the exterior and a roller on the interior supports. I’m using a Nonlinear Static (P-Delta) load case to consider the stiffening effects of the tension in the cables. The applied distributed load then uses the stiffness from this Nonlinear tension case. However my question is this, would the applied distributed load also need to be a Nonlinear Static (P-Delta) load case, or simply a Static Load case (the displacement results vary greatly between the two)? Thank you in advance for any suggestions you may have.

 

[IJR]

psu

I recommend you model using frame elements, and not the cable element.

Then since you have an elastic cable and span loads(uniformly distributed or point loads, it wont matter), try to use the nonlinear P-delta with large displacement. Your cable will then take up a final shape and you will see that all forces are tensile.

Make sure there is no other frame element other than the one representing the cable. Mixing frame elements will give you strange results when usign P-D with large delta.

I used this a couple of time for vertical loadings, and it worked out fine.