Unbalanced moment in punching design (Eurocode 2)
Unbalanced moment in punching design (Eurocode 2)
(OP)
Hi everyone!
I have a basic question. When you design a slab-column joint for punching shear in Eurocode 2, in the equation of the factor betta:
- should MEd (the unbalanced moment) be calculated using an elastic linear analysis?
Never mind seismic actions at this moment, let's assume that eccentricity is due to building geometry only. How would you support your answer?
I have a basic question. When you design a slab-column joint for punching shear in Eurocode 2, in the equation of the factor betta:
- should MEd (the unbalanced moment) be calculated using an elastic linear analysis?
Never mind seismic actions at this moment, let's assume that eccentricity is due to building geometry only. How would you support your answer?






RE: Unbalanced moment in punching design (Eurocode 2)
1) Analysis of the overall structure.
2) Taking the Med and converting it to stresses at the punching shear plane.
I can't respond specifically about Eurocode off the top of my head. But, for the US / ACI codes you would generally use an Elastic analysis with geometric non-linearity (i.e. P-Delta).
For calculating the stress at the punching shear perimeter this would calculated using an elastic stress distribution.
RE: Unbalanced moment in punching design (Eurocode 2)
Actually, my question is specifically related to Eurocode. In Eurocode you calculate the resisting shear stress and the acting shear stress. In the latter calculation, you consider linear distribution of stresses due to unbalanced moment along the critical perimeter (that's the code). A factor β (beta) is introduced in the calculations as a function of MEd and VEd amongst others. My question is specific for the MEd in the formula for β (beta).
RE: Unbalanced moment in punching design (Eurocode 2)
RE: Unbalanced moment in punching design (Eurocode 2)
that's what I think too.
But when you get into more details (I mean, scientific details), you see that there is room for discussion in this topic.
RE: Unbalanced moment in punching design (Eurocode 2)
RE: Unbalanced moment in punching design (Eurocode 2)
that's logical for design purposes. However, I have been trying to find out what is the background of the Eurocode formulas for punching. So far I have not succeeded.
That would be a new topic, but if any of you have such information, I would appreciate it if you post it here.
RE: Unbalanced moment in punching design (Eurocode 2)
You can take a look the following document, which has extensive background on the Eurocode provisions (Punching starts at page 6-26):
Commentary to Eurocode 2
LinkStudPSR also has a great guide on the calculation of punching shear reinforcement:
Downloads
Direct link for LinkStudPSRDesignManualtoEC2v3.0
If you can read French, I'd recommend the Eyrolles books ("Calcul des structures en béton" or "Maîtrise de l'Eurocode 2").
RE: Unbalanced moment in punching design (Eurocode 2)
Codes in may cases are simplified solutions simply because either there is no practical "scientific" solution or because the scientific solution is too complex and a lower bound solution is adequate, or because in this case in my opinion it is a brittle failure criterion and the elastic case will actually cause the failure. Redistribution due to cracking etc cannot be allowed for in a brittle failure case.
RE: Unbalanced moment in punching design (Eurocode 2)
especially avscorreia for the great links. I had previously "seen" the commentary to Eurocode 2 (quite some time ago) but you reminded me of a good source of information on the background of EC.
I can read French, so I will also check the books you suggested (if I find them).