The reinforced concrete beam which has width 25 cm, lever arm 40 cm, shear force 6 t/cm2, safe shear stress 5 kg/cm2 and B.M. 24 mt,
A. Is safe in shear
B. Is unsafe in shear
C. Is over safe in shear
D. Needs redesigning
Answer: Option B
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Distribution of shear intensity over a rectangular section of a beam, follows:
A. A circular curve
B. A straight line
C. A parabolic curve
D. An elliptical curve
If the shear stress in a R.C.C. beam is
A. Equal or less than 5 kg/cm2, no shear reinforcement is provided
B. Greater than 4 kg/cm2, but less than 20 kg/cm2, shear reinforcement is provided
C. Greater than 20 kg/cm2, the size of the section is changed
D. All the above
In a pre-stressed member it is advisable to use
A. Low strength concrete only
B. High strength concrete only
C. Low strength concrete but high tensile steel
D. High strength concrete and high tensile steel
In a simply supported slab, alternate bars are curtailed at
A. $${\frac{1}{4}^{{\text{th}}}}$$ of the span
B. $${\frac{1}{5}^{{\text{th}}}}$$ of the span
C. $${\frac{1}{6}^{{\text{th}}}}$$ of the span
D. $${\frac{1}{7}^{{\text{th}}}}$$ of the span
Acc to IS 456:1978
Max shear stress (q max)
Q max= shear force/lever arm*width
= 6000/40*25 = 6kg/cm2
So shear stress(6)>safe shear stress(5)
So ans B is correct. Unsafe in shear