Why ribs are provided in Steel bars or Reinforcement bars in construction

We used Square or without ribs circular bars a decade before.

But with time when our structure collapsed due earthquake or not able to make a strong bond between Reinforcement and Concrete in structure then we need to think in different ways.

So Ribs are introduced which are continuously all over the Reinforcement and which works as a lock or obstacle for Concrete to slide down once it's set or hardened.

Ribs makes the bond between Reinforcement and Concrete stronger.

Watch the video below for more details about it 

https://youtu.be/76wV7F0CBbs