A pre-stressed rectangular beam which carries two concentrated loads W at $$\frac{{\text{L}}}{3}$$ from either end, is provided with a bent tendon with tension P such that central one-third portion of the tendon remains parallel to the longitudinal axis, the maximum dip h is
A. $$\frac{{{\text{WL}}}}{{\text{P}}}$$
B. $$\frac{{{\text{WL}}}}{{2{\text{P}}}}$$
C. $$\frac{{{\text{WL}}}}{{3{\text{P}}}}$$
D. $$\frac{{{\text{WL}}}}{{4{\text{P}}}}$$
Answer: Option C
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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
Reaction Ra = W.
Reaction Rb = W.
Bending Moment at Center of the Beam = [W * (L/3 + L/6) ]-[W* (L/6) ].
= WL/3.
Now Moment due to prestressing force = P*h (h= maximum dip).
Dip required => P*h = WL/3.
Therefore h = WL/3P.
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