Consider two RCC beams, P and Q, each of width 400 mm and effecti
A. Shear reinforcement should be designed for 175 kN for beam P and the section for beam Q should be revised
B. Nominal shear reinforcement is required for beam P and the shear reinforcement should be designed for 120 kN for beam Q
C. Shear reinforcement should be designed for 175 kN for beam P and the section for beam Q should be designed for 525 kN for beam Q
D. The sections for both beams, P and Q need to be revised
Please scroll down to see the correct answer and solution guide.
Right Answer is: A
SOLUTION
Concept:
As per IS 456:2000
Nominal shear stress = \({\tau _v} = \frac{V}{{bd}}\)
Where, V = Ultimate shear force, b = width of beam, d = effective depth of beam
Nominal shear stress should never be greater than maximum shear stress with shear reinforcement.
Calculation:
Two Beams P & Q of B = 400 mm
d = 7.50 mm
τc, max = 2.0 MPa
τc = 0.75 Mpa
Design shear force for P = 400 kN
Design shear force for Q = 750 kN
For beam P,
Vu = 400 kN
\({\tau _V} = \frac{V}{{bd}} = \frac{{400 \times {{10}^3}}}{{400 \times 750}} = 1.33\;N/m{m^3} < {\tau _{c,\;max}} = 2.0\) N/mm2
⇒ Vus = (1.33 – 0.75) × 400 × 750 = 175 kN
For Beam Q,
Vu = 750 kN
\({\tau _v} = \frac{{750 \times {{10}^3}}}{{400 \times 750}} = 2.5\;N/m{m^2}\; > {\tau _{c,\;max}}\)
So, section for Beam Q should be revised.