Originally Posted by elgaz
If he can move/lift a schoolbus as a child, I don't see why he would be straining that much under a steel girder when he's a fully grown and more powerful adult. Perhaps he's not straining at all and his expression is for a totally different reason.
I don't think it is just a steel girder. Based upon the set photos, it looks likeClark is holding up the base of a large structure that will be extended in post.
I bet he will be holding up something much larger like the entire central steel tower on this oil rig.
Arguably, it seems like Supes won't be moving planets or lifting continents this time around, but I think that is a good thing. I'd prefer a Superman who struggles with lifting things that much larger than a jumbo jet.