Frame with mutipoint constraint? 1

[idly123]

Hi,
We have a frame with an inclined leg. This inclined leg rests on a roller support inclined at 30 degrees to horizontal . If this is to be treated as a mulyi pont constraint problem how do we account for the stifnes contribution from roller support taking in to consideration that the lateral moment at roller is not afffected by the horizontal component of reaction.
regds
Raj

 

[EdR]

Define your MPC so that the proper global DOF times the sine and cosine of the angles gives a normal displacement component of zero.

 

[pjhype]

Or, you could define a local coordinate system at the roller support inclined at 30 degrees and constrain only the motion in the normal direction.

 

[idly123]

Wouldnt the cosine term(horizzontal) calculated from Dof at roller affect the behaviour of he roller in that the horizontal movement at roller would be affected??!

If that is the case can an inclined roller be equivalent to a hinge with a force acting equivalent to the cosin component......can such an argument be valid
please let me know
regds Raj

 

[EdR]

1. If constraint of local coordinate systems is available then pjhype's suggestion is the same as mine and probably easier to accomplish...

2. I didn't really understand your question but maybe this will help...both the horizontal and vertical (assuming these are global dof) deflections will be affected by such a constraint. They will be affected in such a way that their final values will give a zero deflection normal to the inclined slope...Unles otherwise constrained the deflection parallel to the slope will be non-zero..

Ed.R.