The reception won't be **** BECAUSE of steel walls and steel roof if you can place the antenna close to a window pointed in the direction of the transmission tower. It may be **** if you are too far away from the transmission tower, there are large obstacles between your pole barn and transmission tower, the antenna is not pointed in the correct direction, etc.
Look at one of the antenna websites like
http://www.tvfool.com The website has a free tool that can tell you how how likely you are to receive good reception.