It is many years since I saw one of the IH bedplates removed from the floor. My recollection is that the underside looked pretty much like the OP. I think ours were set into a bed of wet concrete or grout and levelled when they were installed in the new building around 1954. Remember, they were permanently set in the floor, not supported on legs.
Some of the applications involved relatively heavy static loading with very little vibration, like the axle dyno. But a few involved extremely violent cyclic mostly vertical loading, probably never envisioned when the building was designed. Think several very large MTS Systems electro-hydraulic linear actuators programmed to shake an entire heavy duty truck cab and hood to simulate driving over a rough road. For weeks. Our large torsion test machine would apply a twisting load to the bedplate between the headstock and tailstock. The Stress Lab applied several ton loads in various directions to components fastened to the bedplate using the overhead chain hoist or hydraulic cylinders. But I do not recall a bedplate being damaged.
The building still stands at 2911 Meyer Rd., Fort Wayne, IN. It has been vacant since a few years after I retired, so I don't know if some bedplates are still in place. Over the years I was there, many of the testing areas with bedplates were converted to office space.
Larry