Laminating steel to wood?

[Maurice Mcmurry]

This is fun stuff to think about. Sagging shelves sure do spoil the look of woodwork. I have made several monuments to inadequate design. I made some bookcases for a preacher 40 years ago with 4 foot long shelves, 3/4 inch plywood edged with 1x2s. He still has them. I married his daughter so I still I get look at those heavily laden shelves, sagging, and smiling back at me.

[Jim Becker]

Just to clarify, it is the extreme fibers in a beam that do the preponderance of the work. ie in an I-beam, it is the flanges, one in tension and one in compression, that are doing the work. The web mostly just holds the flanges together/apart. In the shelf, for example, it is the upper and lower skins, one in tension and one in compression, that are doing the work. Thickening the shelf makes it stiffer, not because the "web" is thicker, but because it separates the skins by a greater distance.

Thanks, Andy. That makes sense.

[Maurice Mcmurry]

This page on woodbin has helpful data.
Shelves - WoodBinhttps://woodbin.com › ref › furniture-design › shelves