Ok, I wasn't talking about the 1997 movie's Grand Staircase, I know it was built differently. (I apologize if I sound rude in the following) but how do you explain the Grand Staircase being missing? even the balustrades?It's time this 'the staircase floated out' nonsense is put to bed once and for all. Just because a look-a-like film set broke free, it doesn't mean that the real staircase did. Also- and this is fundamental I think- 'the staircase' was actually hundreds of individual wooden pieces, and dozens of metal ones. It almost certainly broke up in situ and was dispersed far and wide within the bow section, probbaly mostly aft. Some of it was definitely ejected from the open end of the bow section on bottom impact because ballustrades have been seen there under the boiler pipes, along with the candelabra from the D deck landing.
I think your theory is correct, but tweaked a little. I think the wreckage was the Grand Staircase, just splintered. The majority of it probably lifted up, and splintered within the ship. Then, when she broke in two, the wreckage went down the C and B-Deck First Class Hallways, and out the Bow's open end. Then, the wreckage was dispersed wide through the debris field.