How to calculate the cutting length of bars and determine appropriate zone of lapping in Beam

1) Beam :-

• A concrete beam is a structural element made of reinforced concrete that primarily resists loads applied perpendicularly to its longitudinal axis.
• It is designed to carry and transfer loads from slabs, walls, or other structural components to vertical supports such as columns or foundations.
• Concrete by itself has good compressive strength but poor tensile strength, which is why reinforced concrete beams are typically used. These beams are embedded with steel reinforcement bars (rebars) to resist tensile forces, while the concrete handles the compressive forces. This combination of concrete and steel allows the beam to support significant loads and resist bending, shear, and deflection.
• Clear cover provided in beam is 25 mm.

2) Key Functions of a Concrete Beam:

a) Carry loads: Supports loads from the structure (e.g., roof, floors).

b) Transfer forces: Moves the loads to the supporting columns or walls.

c) Resist bending: The beam resists the forces trying to bend it, with the concrete handling the compression and the steel reinforcement handling the tension.

3) Lapping in Beam :-* The lap length should not be less than the development length of largest longitudinal reinforcement bar in tension.

• Lapping should not provided -

a) Within a joint

b) Within a distance of 2D from face of the column, where D = (Depth of beam - Bottom cover - Stirrup dia - Main bar dia)

• Minimum diameter of a link should be 8 mm.

4) Notation :-

• 4-12# (2+2) - means 4 bars of 12 mm diameter in which 2 are main bars and other 2 are extra bar (either top or bottom).
• 8# 2LG.ST @130 c/c - means 2 legged stirrup having diameter of 8 mm with spacing 130 mm center to center.