RISA 3D graphical representation of Thermal Load

[CCox]

This is probably a question for JoshPlum.

I am retrofitting a bowstring truss with a broken bottom chord. I am using post-tensioned strands to accomplish this. My question is why RISA graphically shows this as a distributed load applied normal to the strand, when it is a thermal load applied axially? The output shows the cable has a tension load applied to it.

Thanks,

Cody

 

[jayrod12]

I haven't done post-tensioned but in Risa I've set the density of some materials to zero when I wanted to ignore the self-weight but run the remaining checks.

Perhaps that would do the trick? Change the density of your cable material to zero but leave the remaining properties the same. Should get rid of the udl you are seeing.

 

[Lomarandil]

No, the thermal load, when applied, looks like a UDL, even though the effect will be axial shortening/lengthening. (It computes out fine)

It's an odd quirk of RISA. Also curious if Josh will weigh in.

 

[JoshPlumSE]

Yes, it is something of an odd quirk in the program. No real explanation... other than it has always been like that.All the way back to the old DOS version of the 1980's / 1990's.

My belief is that it was done that way originally because of limits on what could be easily done graphically. Then it just carried on from version to version and was never a high enough priority to update. Especially considering how much programming work it takes to make changes to our graphics.

I just looked through our "enhancement request" database and didn't see any logged requests for updating this. I will add one now.