[Ocikat]

Gluing the 2x4's to the floor is your best option, the problem in attaching anchors to a post tension slab is twofold, one is drilling into the tension rods and damaging them in the process, which would compromise the structure, this can still be done if you can accuratly locate the tension rods with a metal detector or Xray, ( a stud finder is not the right tool for this ) ( Your building prints will help if they are available however most construction companys don't always build exacltly to the architects drawings) . there is still a probem though, you cannot use a screw, or expansion type device as these will impose a lateral stress on your flooring and it will eventually crack and again this will compromise the structural integrity of your slab. the proper way to install a stud in this type of flooring would be to core drill ( after properly locating the tension rods ) the floor and install the studs in a bed of structural epoxy. kits to do this are available from vendors such as Hilti. you would really only need to do this if your attaching something like a lift or other type of machinery on the floor. The cast spikes you mentioned were placed in the floor during the concrete pour so there would not have been any compromise or lateral tension from them. hope this helps