Design Shear Strength of Concrete

Q. Shear strength of concrete in a reinforced concrete beam is a function of which of the following:

1. Compressive strength of concrete
2. Percentage of shear reinforcement
3. Percentage of longitudinal reinforcement in tension in the section
4. Percentage total longitudinal reinforcement in the section

Select the correct answer using the codes given below:

1. 1, 2 and 4
2. 1, 2 and 3
3. Only 1 and 3
4. Only 1 and 4

Q. Minimum shear reinforcement is provided to

1. resist shear force at the support
2. resist shear on account of accidental torsion
3. arrest the longitudinal cracks on side faces due to shrinkage and temperature variation
4. resist shear in concrete developing on account of non-homogeneity of concrete

Q. The distance between theoretical cut-off point and actual cut-off point in respect of the curtailment of reinforcement of reinforced concrete beams should not be less than

1. Development length
2. 12 $\times$ diameter of bar or effective depth whichever is greater
3. 12 $\times$ diameter of bar or effective depth whichever is smaller
4. 30 $\times$ diameter of bar or effective depth whichever is greater

Q. The maximum pemissible shear stress ${\tau }_{c,max}$ given BIS : 456-1978 is based on

1. Diagonal tension failure
2. Diagonal compression failure
3. flexural tension failure
4. flexural compression failure

Q. If a 2-legged 8 mm diameter HYSD bar is used as shear reinforcement for a beam of width 230 mm and effective depth 300 mm, what is the nearest magnitude of the spacing of minimum shear reinforcement?

1. 420mm
2. 390 mm
3. 350 mm
4. 320 mm

Q. As per IS 456-2000 for the design of reinforced concrete beam, the maximum allowable shear stress $\left({\tau }_{{}_{Cmax}}\right)$ depends on the

1. grade of concrete and grade of steel
2. grade of concrete only
3. grade of steel only
4. grade of concrete and percentage of reinforcement

Q. If the stirrup spacing is equal to 0.75 times the effective depth of an RC beam. then the shear capacity of stirrup steel is equal to

where $f_y$ is strength and $A_{sv}$ is cross-sectional area of the stirrup steel.

1. $1.25\left(f_y{A}_{sv}\right)$
2. $1.16\left(f_y{A}_{sv}\right)$
3. $1.08\left(f_y{A}_{sv}\right)$
4. $1.00\left(f_y{A}_{sv}\right)$

Q.

A rectangular beam of width 230 mm and effective depth 300 mm is proposed to carry a BM and SF of 120 kNm and 270 kN, respectively. If M30 grade of concrete and Fe 415 steel are used for which ${\tau }_{cmax}$ = 3.5 MPa, which one of the following statements is correct?

1. It can be designed as a singly reinforced, under-reinforced section.
2. It can be designed as a doubly reinforced section.
3. The section is unsafe from shear considerations.
4. It can be designed as a doubly reinforced section but it is unsafe from shear considerations

Q. Consider the following statements in the light of IS 456 : 2000:

1. There is an upper limit on the nominal shear stress in beams (even with shear reinforcement) due to the possibility of crushing of concrete in diagonal compression.
2. A rectangular concrete slab whose length is equal to its width may not be a two-way slab for certain definable support conditions.

1. 1 only
2. 2 only
3. Both 1 and 2
4. Neither 1 nor 2

Q. In shear design of an RC beam, other than the allowable shear strength of concrete (${\tau }_c$), there is also an additional check suggested in IS 456-2000 with respect to the maximum permissible shear stress (${\tau }_{cmax})$. The check for $\left({\tau }_{cmax}\right)$ is required to take care of

1. additional shear resistance from reinforcing steel
2. additional shear stress that comes from accidental loading
3. possibility of failure of concrete by diagonal tension
4. possibility of crushing of concrete by diagonal compression

Q. The safe shear resistance of an anchor connector is given by
( K is a coefficient and other symbolshave the usual meanings)

1. 
   $V=K{f}_{sy}{A}_t$
2. $V=K{f}_{sy}^2{A}_t$
3. $V=K{f}_{sy}^{1/2}{A}_t$
4. $V=K{f}_{sy}^{1/2}{A}_t^{1/2}$

Q. Consider the following statements:
1. Reinforcement that is no longer required for flexure beyond a certain section, shall however be extended by d or 12$\varphi$. whichever is greater, before being curtailed.
2. Atleast half the bars should be bent up at the cut-off point.
3. The shear capacity at cut-off point should atleast be 1.5 times the shear force at that section.

Which of these statements are correct?

1. 1 and 2
2. 1 and 3
3. 2 and 3
4. 1, 2 and 3