STAAD Base plate with hole using FEM strange results

[e104909]

Fellows,

Could you help me with this problem?

http://www.eng-tips.com/viewthread.cfm?qid=305365&page=1

Regards,
E104909

 

[bkal]

Hi,

can you explain why are you using 0.4*60MPa as your modulus of subgrade reaction, are you not mixing up strength and stiffness?

When you say (in point 1) that it is not capturing a real behaviour, can you explain in what way?

 

[e104909]

I just assumed 0.4*60 as the bearing capacity of my concrete and that is strength.

Because the baseplate is sitting on concrete pier.

I am also not sure.

But I understand your point. If it is a soil then value of K would have to be Subgrade modulus / allowable displacement multiplied by influence area. But for this case can you correct me?

Because, if i run the analysis and take a look at support reactions it is not realistic. 2nd, the displacement if i animate, it is really not true.

But I cannot think of another way and what is i am missing.

It should'nt behave like that.

Actually this is my first time to do base plate on top of concrete pier. I just want to observe the extent of hole and see how it reacts with the stresses. Though I am confident that it shouldnt be an issue because it is outside the bearing area. But i just want to make sure and prove it.

what is your idea?

Regards,
E104909

 

[bkal]

I am not sure if it matters in why your results seem to be wrong, but Young's modulus of concrete is probably of the order tof 20,000N/mm2 .

I have no access to STAAD, so if you could post a sketch of your detail as well as screenshoot of your results where you can explain why are they wrong it would help.