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I have an assignment where I need to analyze a structure and have it approved according to the Eurocode 3 standard.
It is a rather simple steel frame that serves two functions. It is used for assembling a series/stack of ventilation devices (filters, heat exchanger etc) onto it, and then, once assembled and transported to customer, it is also used for lifting it into place. It is the lifting that is the critical load case that need to be analyzed.
Setting up the model with constraints, material properties, loads etc is pretty easy. I can run it, and I can extract results, such as stress, strain. I can, if necessary, refine the model and solution, to get a more accurate result etc. It has a few bolt connections that can be modeled in more or less detail.
So far so good.
Now I'm trying to figure out how to relate these results; i.e. stresses, strains, displacements, to the Eurocode 3 standard. This is not straight forward. I called a guy at the Swedish Institute for Standards, who are responsible for issuing these standards in Sweden. He could not give me a straight answer. "It sorta depends"... 😕
The standard describes how to introduce so-called partial factors, i.e. safety factors to account for uncertainties regarding loads, geometry, material properties etc. Also this is pretty straight forward. So given that I know these partial factors, I can run my analysis and calculate, say a maximum stress level. How do I then use this stress (or strain or deformation) to determine wether or not my design fulfils the standard. I.e. what is actually the dimensioning criteria that should be satisfied. The standard says, as far as I can see, that the "design value of effect of actions should be less thatn the design value of the resistance"
What the (*f-word*) does this mean???
i don't think you can use a FEA analysis for eurocode due to stress concentrations (artificial in the fem software). EC3 basically gives you the allowable stress (sigma zulässig) for the given usage conditions/ loads.
i am more familiar with FEM 1.001, but it's basically the same.
there is a software to calculate that but i don't remember its name.
I can use different techniques to refine the FEA model so that it correctly calculates stresses in critical regions. That's just a matter of how detailed/complex I want to make the model. So the stress level from the FEA is correct. It is how to compare this stress and deformation result with Eurocode 3 that is not clear. There are a few paragraph's in Appendix C of "EN 1993-1-5: General rules - Plated structural elements" that mention how to use FEA for Eurocode, but how to establish a dimensioning criteria is not explicitly described.
Anybody out there, who can interpret the Eurocode 3 standard for Mats, when it says:
"design value of effect of actions should be less than the design value of the resistance"