The most standard bike rack in campuses are the ones in the picture. You cannot use it like a pole, where you lock your rear tire through the frame triangle (without the frame) onto a pole, except on the very two ends.
You can lock your bike lengthwise along the rack but that's not possible in crowded campuses.
So, how do you lock your bike in the middle portions of the rack? I know most people put the front wheel of their bike over the top tube of the rack and lock their U-lock through the front wheel, rack, and bike frame. But this constant practice will leave your fork and frame all scratched up til bare metal and beyond.