French term (edited): reprise des charges in this context

Imagine you have just acquired a French country house with old oak floor beams. The beams are spaced 50 cm apart and are all parallel. Trouble is, you want to put in an extra staircase so you needn't run into the servants when you go up to your lover's/mistress's room .... And through years of overeating, there is no way you will fit between the 50 cm gap of a narrow staircase.

Obviously part of one (at least) of those beams will have to go. But that means that the weight of one leg of the grand piano, with its solid gold candelabra, on the upper floor will be supported by the beam whose end has been removed, and no longer spans wall to wall.

The answer? A trimmer joist, one fixed to the end of the shortened beam and to the beams on either side of it, thus spreading the load of that leg of the grand piano across three beams (two spanning wall to wall, one fixed into the wall at one end and supported at the other by a "construction de reprise des charges").

Not only can you make now make love all night and the servants will be none the wiser, but you can also play the piano (funny, you couldn't before and have never taken a lesson in your life) to your heart's content without fear of bringing everything crashing about your ears.

Oh, the joys of French country living!