Purpose and location of steel in concrete is totally depending on the types of the forces we are facing, we use different reinforcement in different locations. The location of reinforcement fall into the following categories.
1: Main reinforcement..
2: Secondary reinforcement.
The main reinforcement is placed in the structural members, to counter the tensile forces produced by the loads ( Live and dead load).
The secondary reinforcement are may subdivided into different types which are
1: Web reinforcement
2: Distribution bars
3: Anchorage bars
a) Web reinforcement:
The web reinforcement is responsible to take care of shearing and diagonal forces. They also tie all the reinforcement mesh together. These reinforcements were not provided in slabs. In Beam it is called Stirrup and in Column it is called Tie.
b) Distribution Bars:
The distribution bars are responsible for distributing the load evenly on the main reinforcement. They also responsible of take care of shrinkage and temperature forces.
c) Anchorage Bars:
The anchorage reinforcement was used at the time of assembly of reinforcement to tie all the reinforcement mesh together.
Read also:- http://www.civilclick.com/read-beam-drawing-plan-site/