I have a transformer with multiple taps on the secondary coil deliverin many different voltages and I want to know if I blow something up when I convert the AC of the transformer to DC with bridge rectifiers and then connet the ground.
Unless the secondaries are made with isolated windings, if you try and add 2 or more bridge rectifiers you will find that commoning up the "ground" output side of the bridges will short out the windings. There are many variations of secondaries with taps but I'm yet to see one that doesn't ALWAYS short out the winding in one direction of current flow.
See this Dave Tweed answer
Also see this answer