Hi,

I am using first time EN 13480 Code in Caesar ii analysis.
Can somebody please confirm whether there is any liberal stress eq for calculating exp stress range like b31.3 in EN13480?

See paragraphs 12.3.4 and 12.1.3.2 in EN-13480.

Hi Richard,

Thanks for your response.

I had read the mentioned paragraphs

Still I am confused whether paragraph 12.3.4 speaks about operating stress or liberal expansion stress for sigma4 stresses.

Can you please through some light on this?

Hi,

Can any body please help on my above query.

Actually B31.3 had also removed Operating stresses (app p),So I am having doubt whether EN13480 speaks about liberal stress or operating stress in sigma 4 stresses in paragraph 12.3.4?

The original intention of B31.3 was to calculate a range stress under the combined loading of weight, pressure and thermal expansion (strain) between cold and hot and to limit it as Syc+Syh or (1.5*Sc)+(1.5*Sh), with an appropriate safety factor. Cannot say it is "operating" stress, it is a range. Same is true for EN 13480, with a different rule.

To simplify the calculation in B31.3 the range was considered for displacement stress only, as a subset of the range described above but setting conservatively the "sustain" to Sh.

"Liberal stress" means that, when calculate the allowable displacement stress range , you may remember how the original range was defined and consider there is a difference between the calculated sustained longitudinal stress and the allowable Sh.

You can see that 12.3.4-1 is similar with B31.3 equation that evaluates the displacement range stress by setting the sustain stress to Sh (without "liberal stress").

12.3.4-2 rather addresses the "original" range stress of B31.3; because the formula does not set the sustain stress to Sh, you may consider it includes what we call here "the liberal stress".