Example of the Design of Shear reinforcement in a beam

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Design of Shear reinforcement in a beam

A reinforced cement concrete beam 300mm wide and 500mm effective depth is subjected to a shear force of 40KN at the ends. The beam is provided with 6 bars of 20mm diameter of which 3 bars are cranked at 45 degrees. Design the shear reinforcement for M20 grade concrete.

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

Width of the beam = b = 300mm

Shear force = Vu = 40KN

Effective depth = d = 500mm

Area of steel, Ast = 3 x 3.14/4 x 20 x 20 = 942.47 mm2

Step one

Nominal shear stress

Tv = Vu/bd

Tv = 40 x 1000/(300 x 500) = 0.26N/mm2

Step two

Percentage of steel

Percent steel = Ast/bd x 100

Percent steel = (942.47 x 100)/ (300×500)

= 0.63%

Step three

As per IS: 456: 2000

Tc = 0.48 + (0.56-0.48)/(0.75-0.5) (0.63 – 0.5)

Tc= 0.52 N/mm2

Therefore, Tv < Tc

No shear reinforcement required.

Step four

Provide minimum shear reinforcement;

As per IS : 456 : 2000

Asv/bsv = 0.4/(0.87 fy)

Assuming 6mm diameter, 2 – legged stirrups

Asv = (2 x 3.14 x 6 x 6)/4 = 56.54 mm2

Sv = (0.87fy.Asv)/0.4b

Sv = (0.87 x 250 x 56.54)/(0.4×300) = 102.47mm say 100mm

As per IS:456:2000,

Maximum spacing = 0.75d

= 0.75 x 500

= 375mm

Provide 6mm diameter, 2-legged stirrups@100mm c/c.

Maximum spacing = 0.75d

= 0.75 x 230 = 172mm

Provide 6mm diameter 2-legged stirrups @ 100mmc/c

Shear reinforcement in a Beam
Shear reinforcement in a Beam

22 thoughts on “Example of the Design of Shear reinforcement in a beam”

      • Dear Madam,

        I found your one of the beam detailing page, which is quite informative.

        I’ve an query regarding beam steel reinforcement detailing that, in the End of the beam do the making of L shape in the rebar is essential in all the cases, specially in the ends of the Beam?

        Please educate me if you have a time. I am an sit civil engineer working in the construction projects. It ll be highly appreciable if u could answer.

  2. hi experts, i have i query about my house in my house have a porch 15feet x 6 feet laying on four column (250mm x 250 mm) porch beam ( 250mm wide x depth is 350mm along with slab ) beam have only four 10mm bar tie with 6mm @150mm is it possible to construct 6 feet high parapet brick wall above slabe any suggetion please.

    • Site Engineer and Structural engineer both have good scope. But there is a lot of hard work you have to do if you are a site engineer. Your whole and sole work is to monitor the activities on the site. Whereas if you are a Structural Engineer, your work is limited to structural drawings accompanied by a couple of site visits.
      Structural Engineer makes more money than a Site Engineer. And of course, if you are looking at future scope, then Structural Engineers have hell lot of scope everywhere in the world.

      Cheers!

  5. I would to thankx who provide it & i like it too much…..but, it is necessary new idea & concept(to reduce like the effect of earthquake) to design shear reinforcement

  6. Indeed the site engineer has more work to do in the field but these are easy to do only more paper works like daily time records, accomplishment report equipment utilization reports,etc. However being a structural engineer requires specialty of engineering. In field, you will observe that the structural engineer has less work to do. But in reality hidden from the outside world, it takes a lot of time of researches, studies, calculations, analysis, comparison etc to hone the skills. Indeed structural engineers command higher salary. I once worked as a site engineer in a hydro dam before becoming a structural engineer at present. I hope this will enligthen

  7. Hi,

    Its mahesh here i completed BE in Civil engineering i would like to work in structural engineering field. Is this qualification enough to work in same field or M.Tech is must..?
    Is there any alternate way get into the Structural field…?

    • Hello Abhijit,
      We haven’t yet covered the topics of bridge design | STeel structures. We will be doing that soon. We will inform you whenever it is done.
      Cheers 🙂

  15. Please give their complete solution immediately …..>A simply supported beam of size(300×550) effective is reinforced with 5-20#bars. It is subjected to a factored shear force of 300kN at support. Design the shear reinforcement if 2-20# bar are bent at a distance of 650mm from face of support. The material are M-20 grade of concrete and HYSD Fe-415 steel.

  16. while finding Nominal Shear Stress, we have to convert Shear Stress to factored shear stress.
    That means factored shear stress (Vu)= 1.5 * shear stress

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