Plain cement concrete has low tensile strength. A beam made up of plain cement concrete will have low load carrying capacity and will fail by cracking in the tension zone. It is therefore reinforced by placing steel bars in the tensile zone. These bars will take up the tensile stresses and thus increase the load carrying capacity or strength of the beam. The steel placed in the tensile zone, is called as longitudinal steel or main steel.
Types of R.C.C. Beams
R.C.C, beams are of following three types:
- Singly Reinforced Beams
- Doubly Reinforced Beams
- Flanged Beams (T beams and L beams)
Singly Reinforced Beams:
The beams in which steel reinforcement is placed in the tensile zone only are called as singly reinforced beams.
Doubly Reinforced Beams:
The beams in which reinforcement is placed in the tensile as well as compression zone are called as doubly reinforced beams.
Flanged Beams (T beams and L beams):
In most reinforced concrete structures the slab, and beams are cast monolithic. Thus, the beam forms a part of the floor system. When the beam bends, a part of the slab also bends along with the beam. So the intermediate beams in a floor system act as T beams and the end beams as L beams. The beams in which a portion of the slab acts together with the beam for resisting compressive stresses are called as flanged beams.