View Single Post
  #2092  
Old Posted Jan 20, 2022, 5:32 PM
ardecila's Avatar
ardecila ardecila is offline
TL;DR
 
Join Date: Jun 2006
Location: the city o'wind
Posts: 16,356
Quote:
Originally Posted by Fvn View Post
Rebar mats like this are actually pretty "hollow" since all rebar structures are generally massive cages. The reinforcement cage for a mat foundation consists of a thicker layer of rebar on the bottom and the top with supporting bars to hold the top layer up/tie the layers together. The ends of the top and bottom bars are also bent at 90 and then tied together with additional bars which makes it even more like a cage. A mat like this could only have 10 actual layers of rebar.
Yeah the greatest forces on a horizontal element (like a beam or a foundation) are always concentrated at the top and bottom so that's where you put the reinforcement.

It's also why I-beams have heavy top and bottom plates and a pretty thin web connecting them, and you can even cut holes in the web without affecting the strength (note: don't try this at home, kids).
__________________
la forme d'une ville change plus vite, hélas! que le coeur d'un mortel...
Reply With Quote