I did some testing of the loot tables for some various tel var boxes.
I opened 50 Reactive armor boxes, I got 0 pieces in sturdy.
I opened 50 Black Rose armor boxes, I got 0 pieces in sturdy.
I opened 50 Imperial Physique boxes, I got 4 pieces in sturdy: 1 in light, 1 in medium, 2 in heavy armor.
It appears that the tel var boxes dedicated to heavy armor alone do not get this trait on their loot tables. Now, I understand sturdy is not a very popular trait; the reason I see this as an issue is that armor sets like Black Rose and Reactive benefit tanks, and I know many tanks that desire at least one or two pieces to be in sturdy. I personally wanted to test out how well 5pc black rose and eight sturdy traits would fare.
@Wrobel If you would consider putting sturdy in the loot tables for the heavy armor boxes in Imperial City, it would be much appreciated. I would like to see increased armor diversity, and for some builds, having sturdy is a must.