How to calculate end rotation for a truss

[psuarcher]

I am trying to calculate the end rotation of a truss for pot bearings. What units should my deflections and lengths be in?

 

[Ron]

It's a pinned connection...shouldn't rotate.

 

[hokie66]

Deflections and lengths, use mm.

 

[csd72]

Ron,

What exactly stops it from rotating?

psuarcher,

Radians are dimensionless so as long as you use consistent units throughout you will be fine.

If in doubt, put your units into the formula and see what it comes out as.

 

[Ron]

csd72...if you get significant deflection in the truss you will get a modicum of rotation; however, such rotation is so small that designing the bearing for such is, in my opinion, a waste of time. The bottom chord (or intersecting members..depending on geometry) stiffness will control, to some degree, the stress distribution across the bearing surface.

So then you have to decide where the rotation actually occurs....is it over the bearing surface (not likely) or is it just off the bearing surface?