In the CEASAR model I am currently working on I have a restraint at node 2000 defined as +Y and X. I have a displacement defined at this restraint, via 20001 CNode, of 0.5" in the X direction only. This is intended to simulate seismic movement of the building in which the line represented by the model is located. The displacement is defined for the CNode 20001 as X=0.5, all other degrees of freedom as 0.0. I have a number of load cases which I will not go into here. Suffice it to say that for some cases CAESAR reports a vertical load as if the restraint were modelled as a Y, instead of a +Y. Can anyone explain what is wrong here?

Yes, you are looking at a combination case, which you should not be. Only look to load cases of native loads (W+T1+P1 for example) and not combinations (L1-L2 for example) when determining restraint loads. For example, say I have three load cases and their associated restraint loads as follows:

L1 = W+P1+T1 (OPE) Fy = 0 lb (lift-off)
L2 = W+P1 (SUS) Fy = -550 lb (weight on restraint)
L1-L2 (EXP) Fy = 0 -(-550) = +550 lb.

This of course is impossible, but that is how an algebraic combination is done. We look at the EXP case for stress because they are computed correctly, but restraint loads and displacements are not.

Dear Goodsalt,

Just want to add link to previous post:
http://www.coade.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=18899&page=1#Post18899
http://www.coade.com/ubbthreads/ubbthrea...=true#Post14855

I also want to paste Sir Loren Brown's point from second link.

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"ONLY stress as the Output Type for your combination load cases (this include EXP as well). Displacements, Forces and Moments are NOT REAL in combination load cases"
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We can browse also for Static Load Case Setup / Modification:
http://www.coade.com/support_tutorial.asp

In Static Analysis dialogue box, for combination load cases in load case options output type should Stress. This is the conclusion. The reason is as already explained by Sir Loren Brown.