How should I connect a steel I beam to the sill plate above it?
Drew is correct. You can remove the bent nails to have your new wall ensure it won't go anywhere. However, you can drill a few small holes, like every 4', out by the outer edge of the flange to pop in some screws or nails...nothing major is needed at all. You just don't want to do anything to the inner "I" that may compromise the engineering. That's actually pretty much impossible to do anyway in a residential situation, unless you wanted to cut or drill big holes in the I-beam.