Design of Vertical Stirrups

Q. A rectangular beam of 230 mm width and effective depth = 450 mm, is reinforced with 4 bars of 12 mm diameter. The grade of concrete is M 20, grade of steel is Fe500. Given that for M20 grade of concrete, the ultimate shear strength ${\tau }_{uc}=0.36N/m{m}^2$ for steel percentage of p = 0.25, and ${\tau }_{uc}=0.48N/m{m}^2$ for steel percentage p = 0.5. For a factored shear force of 45 kN, the diameter (mm) of Fe500 steel 2 legged stirrups to be used at spacing of 375 mm should be

1. 8
2. 10
3. 12
4. 16

Q. Minimum shear reinforcement in beams is provided in the form of stirrups

1. to resist extra shear force due to live load
2. to resist the effect of shrinkage of concrete
3. to resist principal tension
4. to resist shear cracks at the bottom of beam

Q. What is the adoptable maximum spacing between vertical stirrups in an RCC beam of rectangular cross-section having an effective depth of 300 mm?

1. 300mm
2. 275mm
3. 250mm
4. 225mm

Q. If the nominal shear stress $\left({\tau }_v\right)$ at a section does not exceed the permissible shear stress $\left({\tau }_c\right)$

1. minimum shear reinforcement is still provided
2. shear reinforcement is provided to resist the nominal shear stress
3. no shear reinforcement is provided
4. shear reinforcement is provided for the
   difference of the two

Q. Diagonal tension reinforcement is provided in a beam as

1. longitudinal bars
2. bent up bars
3. helical reinforcement
4. 90° bend at the bends of main bars

Q. In a combined footing, in the zones where the shear stresses are less than $5kg/c{m}^2$, stirrups to be provided are generally

1. 2-legged
2. 4-legged
3. 8-legged
4. 12-legged

Q. Shear resistance of concrete in a reinforcement beam is dependent on

1. Tension reinforcement in the beam
2. Compression reinforcement in the beam
3. Shear reinforcement in the beam
4. None of the reinforcement in the beam

Q. How can shear strength be ensured in a beam?

1. By providing binding wire on main bars
2. By providing HYSD bars instead of mild steel bars
3. By providing rounded aggregate
4. By providing stirrups

Q. Torsion resisting capacity of a given RC section

1. decreases with decrease in stirrup spacing
2. decreases with increase in longitudinal bars
3. does not depend upon stirrup and longitudinal steels
4. increases with the increase in stirrup and longitudinal steels

Q. Directions: The following items consists of two statements; one labelled as 'Assertion (A)' and the other as 'Reason (R)'. You are to examine these two statements carefully and select the answers to these items using the codes given below:

Codes:
(a) both A and R are true and R is the correct explanation of A
(b) both A ·and Rare true but R is not a correct explanation of A
(c) A is true but R is false
(d) A is false but R is true

Assertion (A): Minimum shear reinforcement as stirrups must be provided in beams, even if the shear stress ${\tau }_v$ is less than the shear strength of concrete ${\tau }_c$.

Reason (R) : The bending of beams creates a tendency in the particles to slide upon each other with the beam. This tendency is called shear.

1. both A and R are true and R is the correct explanation of A
2. both A and Rare true but R is not a correct explanation of A
3. A is true but R is false
4. A is false but R is true

Q. Consider two RCC beams, P and Q each having the section 400 mm x 750 mm (effective depth, d = 750 mm) made with concrete having a ${\tau }_{cmax}=2.1N/m{m}^2$. For the reinforcement provided and the grade of concrete used, it may be assumed that the ${\tau }_c=0.75N/m{m}^2$. The design shear in beam P is 400 kN and in beam Q is 750 kN. Considering the provisions of IS : 456-2000, which of the following statements is true?

1. Shear reinforcement should be designed for 175 kN for beam P and the section for beam Q should be revised.
2. Nominal shear reinforcement is required for beam P and the shear reinforcement should be designing for 120 kN for beam Q.
3. Shear reinforcement should be designed for 175 kN for beam P and the shear reinforcement should be designed for 525 kN for beam Q.
4. The sections for both beams P and Q need to be revised.

Q. Match List-I (Reinforcement type) with List-II
(Anchorage requirement) and select the correct
answer using the codes given below the lists:
List-I
A. Footing slab, tensile reinforcement
8. Cantilever beam, tensile reinforcement
C. Simply supported beam, tensile reinforcement
D. Beam, shear stirrup
List-I
1 $\frac{L_d}{3}$ into the support
2. 6$\varphi$ for 135° bend
3. $L_d$ into the support
4. $L_d$ from the column face
Codes:
A B C D

1. 1 3 4 2
2. 1 2 4 3
3. 4 3 1 2
4. 4 2 1 3