How does struts in KSP works?

[RainDreamer]

Are they like struts in real life, as in they can be used to hold things in place, resist compression, separate 2 things from each other, and can hold up against gravity? Or are they like space ropes that use tension to hold things in place, and can't hold things up?

Edited December 7, 2014 by RainDreamer

[Zylark]

They behave more or less like a steel rebar that reinforce an existing connection. It will stretch, compress and twist - even snap - depending on what and how strong a force is applied to it. So whilst struts do add rigidity to the connection of two parts, how much rigidity depends on how you strut, and how many struts you apply.

For instance if you got two 2.5m tanks connected through two 1.25m docking ports, having 4 struts that just go straight up/down from the one tank to the other won't be very efficient, and still cause considerable flexibility in the connection if under stress. Configure those same four struts into two X'es or V'es, one on either side, and you'll get a very rigid connection.

edit: like so:

Oh, and the struts will disappear if you decouple or undock the connection the struts support.

Edited December 7, 2014 by Zylark

[RainDreamer]

So basically they are hard structures that are rigid and can withstand compression? I thought they were like space tapes that use tension to hold things together and would fail if there were some slack. That is helpful to know.

I have a cargo that is needed to be held up and away from the cargo bay floor of my space plane, so I was wondering if I can use struts for that purpose, instead of having to build more structure that hold them up.

Edited December 7, 2014 by RainDreamer

[Zylark]

Struts are great for keeping cargo in place inside a cargo-bay. Have two struts on either side, going down to the floor or lower part of sidewall in an inverted V, and your cargo should sit tight and not bounce around.

As far as tension and compression strength is concerned, I think it is equal in both directions. I don't know how much it is, but I've seen them (ahem, slightly top-heavy payload...) stretch and compress quite significantly, perhaps up to half their length, before snapping.