Guide to Design of Shear Reinforcement in a beam

Design of Shear Reinforcement in a beam

The beam is failed by the diagonal tension in which the cracks start from support and extend upto a distance equal to effective depth and making an angle more or less than 45 degrees.

Shear reinforcement diagram (beam longitudinal section)
Shear reinforcement diagram (beam longitudinal section)

Here are the steps for the design of Shear Reinforcement in a beam:

Step one

Nominal shear stress

Tv = Vu/bd

Where, Vu = shear force due to design load

b = width of the beam

d = depth of the beam

Step two

Percentage of steel

Percent steel = Ast/bd x 100

Step three

Find the shear stress in concrete (Tc) for the above percentage of steel as per IS:456:2000

Step four

If, Tv < Tc

No shear reinforcement is required. However, nominal stirrups are provided and their spacing is determined by,

Asv/b.Sv= 0.4/(0.87fy)

Where, Sv = spacing of stirrups

Asv = Area of stirrups

In any case, the spacing should not be more than  0.75d

Step five

If, Tv > Tc

Sv = 0.87fy. Asv. d/(Vus)

Where, Vus = strength of shear reinforcement

Here’s an example of the design of Shear reinforcement of a beam:

Example of shear reinforcement of a beam

6 thoughts on “Guide to Design of Shear Reinforcement in a beam”

  1. i saw a building been constructed and it has been divided into 3 different sections with the provision of expansion joints .Why the expansion joint?

    • Expansion joints can be used if the facades are huge. If the building is divided into three sections with the help of expansion joints, the cracks that occur due to heat induced expansion or contraction of various materials can be prevented. It also helps in absorption of vibrations.
      Expansion joints are not generally used in buildings, they are preferably used in bridges, sidewalks, railway tracks, piping systems etc. In case the building to be constructed is huge and falls in an earthquake prone zone, then expansion joints are used to prevent the structure from damage of vibrations.

  2. You steps for the design of Shear Reinforcement in a beam is really amazing. I am an engineering enthusiast and I am learning from this. Thanks.

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