Theory Of Structures(Civil Engineering ) Questions and Answers

Question 1. A simply supported beam A carries a point load at its mid span. Another identical beam B carries the same load but uniformly distributed over the entire span. The ratio of the maximum deflections of the beams A and B, will be
  1.    $$\frac{2}{3}$$
  2.    $$\frac{3}{2}$$
  3.    $$\frac{5}{8}$$
  4.    $$\frac{8}{5}$$
Explanation:-
Answer: Option D. -> $$\frac{8}{5}$$
$$\eqalign{
& {\text{Deflection max }}\left( {\text{A}} \right) = \frac{{{\text{P}}{{\text{L}}^3}}}{{48{\text{E}}I}} \cr
& {\text{Deflection max }}\left( {\text{B}} \right) = \frac{{5{\text{w}}{{\text{L}}^4}}}{{384{\text{E}}I}};\,\,\,\left( {{\text{w}} = \frac{{\text{P}}}{{\text{L}}}} \right) \cr
& = \frac{{5{\text{P}}{{\text{L}}^3}}}{{384{\text{E}}I}} \cr
& {\text{Ratio}} = \frac{{{\text{P}}{{\text{L}}^3}}}{{48{\text{E}}I}} \times \frac{{384{\text{E}}I}}{{5{\text{P}}{{\text{L}}^3}}} = \frac{8}{5} \cr} $$
Question 2. Principal planes are subjected to
  1.    Normal stresses only
  2.    Tangential stresses only
  3.    Normal stresses as well as tangential stresses
  4.    None of these
Explanation:-
Answer: Option A. -> Normal stresses only
Question 3. A shaft is subjected to bending moment M and a torque T simultaneously. The ratio of the maximum bending stress to maximum shear stress developed in the shaft, is
  1.    $$\frac{{\text{M}}}{{\text{T}}}$$
  2.    $$\frac{{\text{T}}}{{\text{M}}}$$
  3.    $$\frac{{2{\text{M}}}}{{\text{T}}}$$
  4.    $$\frac{{2{\text{T}}}}{{\text{M}}}$$
Explanation:-
Answer: Option C. -> $$\frac{{2{\text{M}}}}{{\text{T}}}$$
Question 4. A masonry dam (density = 20,000 N/m3) 6 m high, one metre wide at the top and 4 m wide at the base, has vertical water face. The minimum stress at the base of the dam when the reservoir is full, will be
  1.    75 N/m2
  2.    750 N/m2
  3.    7,500 N/m2
  4.    75,000 N/m2
Explanation:-
Answer: Option C. -> 7,500 N/m2
Question 5. Y are the bending moment, moment of inertia, radius of curvature, modulus of If M, I, R, E, F and elasticity stress and the depth of the neutral axis at section, then
  1.    $$\frac{{\text{M}}}{{\text{I}}} = \frac{{\text{R}}}{{\text{E}}} = \frac{{\text{F}}}{{\text{Y}}}$$
  2.    $$\frac{{\text{I}}}{{\text{M}}} = \frac{{\text{R}}}{{\text{E}}} = \frac{{\text{F}}}{{\text{Y}}}$$
  3.    $$\frac{{\text{M}}}{{\text{I}}} = \frac{{\text{E}}}{{\text{R}}} = \frac{{\text{F}}}{{\text{Y}}}$$
  4.    $$\frac{{\text{M}}}{{\text{I}}} = \frac{{\text{E}}}{{\text{R}}} = \frac{{\text{Y}}}{{\text{F}}}$$
Explanation:-
Answer: Option C. -> $$\frac{{\text{M}}}{{\text{I}}} = \frac{{\text{E}}}{{\text{R}}} = \frac{{\text{F}}}{{\text{Y}}}$$
Question 6. A rolled steel joist is simply supported at its ends and carries a uniformly distributed load which causes a maximum deflection of 10 mm and slope at the ends of 0.002 radian. The length of the joist will be,
  1.    10 m
  2.    12 m
  3.    14 m
  4.    16 m
Explanation:-
Answer: Option D. -> 16 m
Question 7. Maximum strain theory for the failure of a material at the elastic limit, is known as
  1.    Guest's or Trecas' theory
  2.    St. Venant's theory
  3.    Rankine's theory
  4.    Haig's theory
Explanation:-
Answer: Option B. -> St. Venant's theory
Question 8. A body is said to be in equilibrium if
  1.    It moves horizontally
  2.    It moves vertically
  3.    It rotates about its C.G.
  4.    None of these
Explanation:-
Answer: Option D. -> None of these
Question 9. The stiffness of the close coil helical spring is
  1.    $$\frac{{{{\text{d}}^4}{\text{N}}}}{{8{{\text{D}}^3}{\text{n}}}}$$
  2.    $$\frac{{{{\text{d}}^4}{\text{N}}}}{{4{{\text{D}}^3}{\text{n}}}}$$
  3.    $$\frac{{4{{\text{D}}^3}{\text{N}}}}{{{{\text{d}}^4}{\text{n}}}}$$
  4.    $$\frac{{8{{\text{D}}^3}{\text{N}}}}{{{{\text{d}}^4}{\text{n}}}}$$
Explanation:-
Answer: Option A. -> $$\frac{{{{\text{d}}^4}{\text{N}}}}{{8{{\text{D}}^3}{\text{n}}}}$$
Question 10. Pick up the correct statement from the following:
  1.    In a loaded beam, the moment at which the first yield occurs is called yield moment
  2.    In a loaded beam, the moment at which the entire section of the beam becomes fully plastic, is called plastic moment
  3.    In a fully plastic stage of the beam, the neutral axis divides the section in two sections of equal area
  4.    All the above
Explanation:-
Answer: Option D. -> All the above
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