Remove roof, save building

How would you go about taking this roof off and saving the steel structure? The concrete block walls will be taken down, but the building owner would like to save the I-beams, joists and columns.

I'm not 100% sure how it was originally installed. But there is a joist every 5'. Every 33" along the joist there is an upside down T. It appears they put some sort of drywall type material in those rectangles, then poured 2" of concrete on top of that, with wire in it. On top of that, there is...

Remove roof, save building

Remove roof, save building