Selections of Steel mech properties to avoid brittle failure

[LICP]

Hi. I'm struggling to select the right mech properties for a S235 or S275 steel. I´m not sure if JR is Ok or I should go to a J0 or J2.
location: Uzbekistan
I got the following outdoor temperature (°C)
Monthly average: 1.5 (jan);3.0(Feb);8.2 (Mar)...13.9(oct); 8.1(nov); 4.1(Dec)
Average annual: 14.8
Absolute min: -20.5
Average max of the coldest month: -2.4

As you can see from monthly/annual average JR looks suitable, but the average of coldest month suggests me to select J2.
J0: 3.5% increase of material cost relative to JR
J2: 4% increase of material cost relative to JR

 

[LittleWheels]

In that environment, I would choose J2 unless you have a reasonable justification to pick a less onerous steel grade (e.g. steelwork within a permanently heated building). What will you do if the heating goes off for a significant length of time?

 

[LICP]

Hi, tks for your reply.
I just found one restriction according to EN 1993-1-10 Material toughness and through-thickness properties, specifically chapter 2.3 "Max permitted thickness values". See attached table 2.1
At the end I see that this introduces a restriction of thickness for high tension. This is something to be highlighted.

Extract form Table 2.1 Max permissible values of element thickness t in mm
________Reference temp. T_Ed °C
________10 0 -10 -20 -30
________ S_ed=0.75fy(t)
s275 JR___55 45 35 30 25
s275 J0___75 65 55 45 35
s275 J2___110 95 75 65 55

so for -20°C for 075fy(t)is just t=30mm
some additional restriction that I'm not taking into consideration?