Learning Forum

[AR]

Hello,

 

I have done an analysis about a struture where the only load applied is the gravity aceleration (then a modal and a response spectrum for an earthquake). However, I have a stress concentration/singulatiry in a joint conection as it is possible to see in the image below:

If I hide this item, the highest stress value is 27 MPa. I have refined the mesh in both items and I have changed the joint with a beam connection, but it does not work. Any tip about how to treat with the stress singularities ? Is there a way to hide only the most stressed part of the item?

Is not the first time when this ocurrs. Is it common to happen?

 

Thanks. Best Regards,

[peteroznewman]

The joint is an idealization of the real connection, but the joint measured the peak force (three components) that went through the joint during the earthquake. Probe the joint to obtain those measurements.

Build a Static Structural detailed model of the real connection around that point in the structure. Apply the force components measured at the joint to the same location in the detailed model.  You can eliminate the stress concentration in the detailed model by using frictional contact to spread the load over an area.

 

[AR]

Hello Peteroznewman,

 

Thank for your answer. I will do that. Related to this topic, do you recommend using Joint or Beam Connection instead 3D bolt model?

[peteroznewman]

If you have a large number of bolts holding a structure together, use joints because they are faster and simpler to use. You can put the forces from each joint in a table, and sort the output to focus on a few joints that have high forces and ignore the many joints that have low forces. Then you can add 3D bolts in only a few places.

[AR]

Ok,

Thank you Peter.

 

Best regards,