# THEORY of STRUCTURES Interview Questions

## 100+ TOP THEORY of STRUCTURES Questions and Answers

Q No: 01
P=4²EI/L² is the equation of Euler’s crippling load if
A. Both the ends are fixed
B. Both the ends are hinged
C. One end is fixed and other end is free
D. One end is fixed and other end is hinged
ANS: A

Q No: 02
Pick up the correct statement from the following:
A. The structural member subjected to compression and whose dimensions are small as
B. compared to its length, is called a stmt
The vertical compression members are generally known as columns or stanchions
C. Deflection in lateral direction of a long column, is generally known as buckling
D. All the above
ANS: D

Q No: 03
0y/n [1 – a (1/r)²]is the empirical formula,
For calculating the allowable stress of long columns
known as
A. Straight line formula
B. Parabolic formula
C. Perry’s formula
D. Rankine’s formula
ANS: B

Q No: 04
Maximum principal stress theory for the failure of a material at elastic point, is known
A. Guest’s or Trecas’ theory
B. St. Venant’s theory
C. Rankine’s theory
D. Von Mises’ theory
ANS: C

Q No: 05
Pick up the correct statement from the following:
A. The moment of inertia is calculated about the axis about which bending takes place
B. If tensile stress is less than axial stress, the section experiences compressive stress
C. If tensile stress is equal to axial stress, the section experiences compressive stress
D. All the above
ANS: D

Q No: 06
A composite beam is composed of two equal strips one of brass and other of steel. If the temperature is raised
A. Steel experiences tensile force
B. Brass experiences compressive force
C. Composite beam gets subjected to a couple
D. All the above
ANS: D

Q No: 07
A shaft subjected to a bending moment M and a torque T, experiences
A. Maximum bending stress = 32M d3
B. Maximum shear stress = 16 T d3
C. Both A. and B.
D. Neither A. nor B.
ANS: C

Q No: 08
A two hinged parabolic arch of span l and rise h carries a load varying from zero at the left end to
A. /4h thrust is
B. /8h
C. /12h
D. /16h
ANS: D

Q No: 09
The horizontal thrust on the ends of a two hinged semicircular arch of radius carrying
A. A uniforml 4/3
B. end, is
C. All the above
ANS: C

Q No: 10
Maximum strain theory for the failure of a material at the elastic limit, is known as
A. Guest’s or Trecas’ theory
B. St. Venant’s theory
C. Rankine’s theory
D. Haig’s theory
ANS: B

Q No: 11
Slenderness ratio of a long column, is
A. Area of cross-section divided by radius of gyration
B. Area of cross-section divided by least radius of gyration
C. Radius of gyration divided by area of cross-section
D. Length of column divided by least radius of gyration
ANS: D

Q No: 12
A close coil helical spring when subjected to a moment M having its axis along the axis of the helix
A. It is subjected to pure bending
B. Its mean diameter will decrease
C. Its number of coils will increase
D. All the above
ANS: A

Q No: 13
The ratio of the stresses produced by a suddenly applied load and by a gradually applied load on a bar, is
A. 1/4
B. 1/2
C. 1
D. 2
ANS: D

Q No: 14
Maximum shear stress theory for the failure of a material at the elastic limit, is known
A. Guest’s or Trecas’ theory
B. St. Venant’s theory
C. Rankine’s theory
D. Haig’s theory
ANS: A

Q No: 15
A cantilever of length is subjected to a bending moment at its free end. If EI is the flexural rigidity of the section, the deflection of the free end, is
A. ML/EI
B. ML/2EI
C. ML²/2EI
D. ML²/3EI
ANS: D

Q No: 16
Pick up the correct statement from the following:
A. For channels, the shear centre does not coincide its centroid
B. The point of intersection of the bending axis with the cross section of the beam, is called shear centre
C. For I sections, the shear centre coincides with the centroid of the cross section of the beam
D. All the above
ANS: D

Q No: 18
If a three hinged parabolic arch, (span l, rise h) is carrying a uniformly distributed load w/unit length over the entire span,
A. Horizontal thrust is wl2/8h
B. S.F. will be zero throughout
C. B.M. will be zero throughout
D. All the above
ANS: D

Q No: 19
The force in BC of the truss shown in the given figure, is
A. 3.0 t compression
B. 3.0 t tension
C. t tension
D. t compression
ANS: C

Q No: 20
P = / L² is the equation for Euler’s crippling load if
A. Both the ends are fixed
B. Both the ends are hinged
C. One end is fixed and other end is free
D. One end is fixed and other end is hinged
ANS: B

Q No: 21
The degree of indeterminacy of the frame in the given figure, is
A. Zero
B. 1
C. 2
D. 3
ANS: B

Q No: 22
The forces in the members of simple trusses, may be analysed by
A. Graphical method
B. Method of joints
C. Method of sections
D. All the above
ANS: D

Q No: 23
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
A. 2/3
B. 3/2
C. 5/8
D. 8/5
ANS: D

Q No: 24
A road of uniform cross-section A and length L
force P. The Young’s Modulus E of the material, is
A. E = /A. L
B. E =/P. L
C. E = P. L/
D. E = P. A/ ANS: C

Q No: 25
In case of a simply supported I-section beam of span L and loaded with a central load W, the length of elasto-plastic zone of the plastic hinge, is
A. L/2
B. L/3
C. L/4
D. L/5
ANS: D

Q No: 26
The yield moment of a cross section is defined as the moment that will just produce the yield stress in
A. The outer most fibre of the section
B. The inner most fibre of the section
C. The neutral fibre of the section
D. The fibre everywhere
ANS: A

Q No: 27
If Ix and Iy are the moments of inertia of a section about X and Y axes, the polar moment of inertia of the section, is
A. (IX + IY)/2
B. (IX – IY)/2
C. IX + IY
D. (I /I )
ANS: C

Q No: 28
A simply supported beam carries varying load from zero at one end and w at the other end. If the length of the beam is a, the maximum bending moment will be
A. wa/27
B. wa²/27
C. w²a
D. wa²
ANS: D

Q No: 29
If E, N, K and 1/m are modulus of elasticity, modulus of rigidity. Bulk modulus and Poisson ratio of the material, the following relationship holds good
A. E = 3K (1 – 2/m)
B. E = 2N (1 + 1/m)
C. (3/2)K (1 – 2/m) = N (1 + 1/m)
D. All the above
ANS: D

Q No: 30
The forces acting on the bar as shown in the given figure introduce
A. Compressive stress
B. Tensile stress
C. Shear stress
D. None of these
ANS: C

Q No: 31
A. Magnitude
B. Direction
C. Point of application
D. All the above
ANS: D

Q No: 33
A body is said to be in equilibrium if
A. It moves horizontally
B. It moves vertically
C. It rotates about its C.G.
D. None of these
ANS: D

Q No: 34
Pick up the incorrect statement from the following: The torsional resistance of a shaft is directly proportional to
A. Modulus of rigidity
B. Angle of twist
C. Reciprocal of the length of the shaft
D. Moment of inertia of the shaft section
ANS: D

Q No: 35
The forces acting normally on the cross section of a bar shown in the given figure introduce
A. Compressive stress
B. Tensile stress
C. Shear stress
D. None of these
ANS: B

Q No: 36
The ratio of circumferential stress to the longitudinal stress in the walls of a cylindrical shell, due to flowing liquid, is
A. ½
B. 1
C. 1½
D. 2
ANS: D

Q No: 37
The load on a spring per unit deflection, is called
A. Stiffness
B. Proof resilience
C. Proof stress
ANS: A

Q No: 38
A compound bar consists of two bars of equal length. Steel bar cross -section is 3500 mm2and that of brass bar is 3000 mm2. These are subjected to a compressive load 100,000 N. If Eb = 0.2 MN/mm2 and Eb = 0.1 MN/mm2, the stresses developed are:
A. b = 10 N/mm2 s = 20 N/mm 2
B. b = 8 N/mm2 s = 16 N/mm2
C. b = 6 N/mm2 s = 12 N/mm2
D. b = 5 N/mm2 s = 10 N/mm2
ANS: A

Q No: 39
A close coil helical spring of mean diameter D consists of n coils of diameter d. If it carries an axial load W, the energy stored in the spring, is
A. 4WD²n/d4N
B. 4W²Dn/d4N
C. 4W²D3n/d4N
D. 4W²D3n²/d4N
ANS: C

Q No: 40
The degree of indeterminacy of the frame in the given figure, is
A. 1
B. 2
C. 3
D. Zero ANS: C

Q No: 42
The moment of inertia of a triangular section (height h, base b) about its base, is
A. bh²/12
B. b²h/12
C. bh3/12
D. b3h/12
ANS: C

Q No: 44
The assumption in the theory of bending of beams is:
A. Material is homogeneous
B. Material is isotropic
C. Young’s modulus is same in tension as well as in compression
D. All the above
ANS: D

Q No: 45
For determining the force in the member AB of the truss shown in the given figure by method of sections, the section is made to pass through AB, AD and ED and the moments are taken about
A. Joint C
B. Joint B
C. Joint D
D. Joint A
ANS: C

Q No: 47
The ratio of crippling loads of a column having both the ends fixed to the column having both the ends hinged, is
A. 1
B. 2
C. 3
D. 4
ANS: D

Q No: 48
A load of 1960 N is raised at the end of a steel wire. The minimum diameter of the wire so that stress in the wire does not exceed 100 N/mm2 is:
A. 4.0 mm
B. 4.5 mm
C. 5.0 mm
D. 5.5 mm
ANS: C

Q No: 50
The maximum deflection due to a uniformly distributed load w/unit length over entire span of a cantilever of length l and of flexural rigidly EI, is
A. wl3/3EI
B. wl4/3EI
C. wl4/8EI
D. wl4/12EI
ANS: C

Q No: 51
A compound truss may be formed by connecting two simple rigid frames, by
A. Two bars
B. Three bars
C. Three parallel bars
D. Three bars intersecting at a point
ANS: B

Q No: 52
The forces acting normally on the cross section of a bar shown in the given figure introduce
A. Compressive stress
B. Tensile stress
C. Shear stress
D. None of these
ANS: A

Q No: 53
A spring of mean radius 40 mm contains 8 action coils of steel (N = 80000 N/mm2), 4 mm in diameter. The clearance between the coils being 1 mm when unloaded, the minimum compressive load to remove the clearance, is
A. 25 N
B. 30 N
C. 35 N
D. 40 N
ANS: C

Q No: 54
If a solid shaft (diameter 20 cm, length 400 cm, N = 0.8 × 105 N/mm2) when subjected to a twisting moment, produces maximum shear stress of 50 N/mm 2, the angle of twist in radians, is
A. 0.001
B. 0.002
C. 0.0025
D. 0.003
ANS: C

Q No: 55
The strain energy stored in a spring when subjected to greatest load without being permanently distorted, is called
A. Stiffness
B. Proof resilience
C. Proof stress
ANS: B

Q No: 56
To determine the force in BD of the truss shown in the given figure a section is passed through BD, CD and CE, and the moments are taken about
A. A joint
B. B joint
C. C joint
D. D joint
ANS: C

Q No: 57
The strain energy due to volumetric strain
A. Is directly proportional to the volume
B. Is directly proportional to the square of exerted pressure
C. Is inversely proportional to Bulk modulus
D. All the above
ANS: D

Q No: 58
A simply supported uniform rectangular bar breadth b, depth d and length L carries an isolated load W at its mid-span. The same bar experiences an extension e under same tensile load. The ratio of the maximum deflection to the elongation, is
A. L/d
B. L/2d
C. (L/2d)²
D. (L/3d)²
ANS: C

Q No: 59
A simply supported beam which carries a uniformly distributed load has two equal overhangs. To have maximum B.M. produced in the beam least possible, the ratio of the length of the overhang to the total length of the beam, s
A. 0.207
B. 0.307
C. 0.407
D. 0.508
ANS: A

Q No: 60
In the truss shown in given figure the force in member DC is
A. 100 t compressive
B. 100 t tensile
C. Zero
D. Indeterminate
ANS: C

Q No: 61
Pick up the correct statement from the following:
A. A wire wound in spiral form, is called a helical spring
B. The pitch of a close coil spring, is very small
C. The angle made by the coil with horizontal, is called the angle of helix
D. All the above
ANS: D

Q No: 62
The ratio of lateral strain to axial strain of a homogeneous material, is known
A. Yield ratio
B. Hooke’s ratio
C. Poisson’s ratio
D. Plastic ratio
ANS: C

Q No: 63
A short column (30 cm × 20 cm) carries a load P 1 at 4 cm on one side and another load P2at 8 cm on the other side along a principal section parallel to longer dimension. If the extreme intensity on either side is same, the ratio of P1 to P2 will be
A. 2/3
B. 3/2
C. 8/5
D. 5/8
ANS: C

Q No: 64
The force in BF of the truss shown in given figure, is
A. 4t tension
B. 4t compression
C. 4.5t tension
D. 4.5t compression
ANS: D

Q No: 65
A. Depth d M
B. Depth d 3
C. Depth d
D. Depth d 1/M
ANS: B

Q No: 66
The ratio of maximum shear stress to average shear stress of a circular beam, is
A. 2/3
B. 3/2
C. 3/4
D. 4/3
ANS: D

Q No: 67
For calculating the permissible stress 0 y /[(1 + a(l/r)²] is the empirical formula, known as
A. Straight line formula
B. Parabolic formula
C. Perry’s formula
D. Rankine’s formula
ANS: D

Q No: 68
Pick up the correct statement from the following:
A. In a loaded beam, the moment at which the first yield occurs is called yield moment
B. In a loaded beam, the moment at which the entire section of the beam becomes fully plastic, is called plastic moment
C. In a fully plastic stage of the beam, the neutral axis divides the section in two sections of equal area
D. All the above
ANS: D

Q No: 69
For a strongest rectangular beam cut from a circular log, the ratio of the width and depth, is
A. 0.303
B. 0.404
C. 0.505
D. 0.707
ANS: D

Q No: 70
Pick up the correct statement from the following:
A. Mcg = M M2 + r2) where letters carry their usual meanings
B. Tcp = m2 + T2)where letters carry their usual meanings
C. The torque which when acting alone would produce maximum shear stress equal to the maximum shear stress caused by the combined bending and torsion, is called equivalent torque
D. All the above
ANS: D

Q No: 71
m1 and m2 are the members of two individual simple trusses of a compound truss. The compound truss will be rigid and determinate if
A. m = m1 + m2
B. m = m1 + m2 + 1
C. m = m1 + m2 + 2
D. m = m + m + 3
ANS: D

Q No: 72
The maximum B.M. due to an isolated load in a three hinged parabolic arch, (span l and rise h) having one of its hinges at the crown, occurs on either side of the crown at a distance
A. l/4
B. h/4
C. l
D. l
ANS: C

Q No: 73
The greatest load which a spring can carry without getting permanently distorted, is called
A. Stiffness
B. Proof resilience
C. Proof stress
ANS: D

Q No: 74
The force in AC of the truss shown in the given figure, is
A. 5t tension
B. 4t tension
C. 4t compression
D. 5t compression
ANS: B

Q No: 75
A bar L metre long and having its area of cross-section A, is subjected to a gradually applied tensile load W. The strain energy stored in the bar is
A. WL/2AE
B. WL/AE
C. W²L/AE
D. W²L/2AE
ANS: D

Q No: 76
The maximum bending moment for a simply supported beam with a uniformly distributed load w/unit length, is
A. WI/2
B. WI²/4
C. WI²/8
D. WI²/12
ANS: C

Q No: 77
An isolated load W is acting at a distance a from the left hand support, of a three hinged arch of span 2l and rise h hinged at the crown, the horizontal reaction at the support, is
A. Wa/h
B. Wa/2h
C. 2W/ha
D. 2h/Wa
ANS: B

Q No: 78
The force in CD of the truss shown in given figure, is
A. 3t compression
B. 3t tension
C. Zero
D. 1.5t compression
ANS: C

Q No: 79
At any point of a beam, the section modulus may be obtained by dividing the moment of inertia of the section by
A. Depth of the section
B. Depth of the neutral axis
C. Maximum tensile stress at the section
D. Maximum compressive stress at the section
ANS: B

Q No: 80
The ratio of the area of cross-section of a circular section to the area of its core, is
A. 4
B. 8
C. 12
D. 16
ANS: D

Q No: 81
The ratio of maximum and average shear stresses on a rectangular section, is
A. 1
B. 1.25
C. 1.5
D. 2.5
ANS: C

Q No: 82
In the truss shown in the given figure, the force in member BC is
A. 100 t compressive
B. 100 t tensile
C. Zero
D. Indeterminate
ANS: C

Q No: 83
If a concrete column 200 × 200 mm in cross-section is reinforced with four steel bars of 1200 mm2 total cross-sectional area. Calculate the safe load for the column if permissible stress in concrete is 5 N/mm2 and Es is 15 Ec
A. 264 MN
B. 274 MN
C. 284 MN
D. 294 MN
ANS: C

Q No: 84
In plastic analysis, the shape factor for rectangular section, is
A. 1.4
B. 1.5
C. 1.6
D. 1.7
ANS: B

Q No: 85
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
A. 75 N/m2
B. 750 N/m 2
C. 7500 N/m 2
D. 75000 N/m2
ANS: C

Q No: 86
A material is said to be perfectly elastic if
A. It regains its original shape on removal of the load
B. It regains its original shape partially on removal of the load
C. It does not regain its original shape at all
D. None of these
ANS: A

Q No: 87
A shaft rotating N.R.M. under a torque T, transmits a power
A. /30 Newton metres/sec
B. /30 Newton metres/min
C. /60 Newton metres/min
D. /60 Newton metres/sec
ANS: A

Q No: 88
If Q is load factor, S is shape factor and F is factor of safety in elastic design, the following:
A. Q = S + F
B. Q = S – F
C. Q = F – S
D. Q = S × F
ANS: D

Q No: 89
The maximum deflection due to a load W at the free end of a cantilever of length L and having flexural rigidity EI, is
A. WL²/2EI
B. WL²/3EI
C. WL3/2EI
D. WL3/3EI
ANS: D

Q No: 90
Pick up the correct statement from the following:
A. For a uniformly distributed load, the shear force varies linearly
B. For a uniformly distributed load, B.M. curve is a parabola
C. For a load varying linearly, the shear force curve is a parabola
D. All the above
ANS: D

Q No: 91
The ratio of the length and depth of a simply supported rectangular beam which experiences maximum bending stress equal to tensile stress, due to same load at its mid span, is
A. 1/2
B. 2/3
C. 1/4
D. 1/3
ANS: B

Q No: 92
A simply supported rolled steel joist 8 m long carries a uniformly distributed load over it span so that the maximum bending stress is 75 N/mm². If the slope at the ends is 0.005 radian and the value of E = 0.2 × 106 N/mm2, the depth of the joist, is
A. 200 mm
B. 250 mm
C. 300 mm
D. 400 mm
ANS: D

Q No: 93
The force in EC of the truss shown in the given figure, is
A. Zero
B. 5t tension
C. 5t compression
D. 4t tension
ANS: C

Q No: 94
The area of the core of a column of cross sectional area A, is
A. (1/3) A
B. (1/6) A
C. (1/12) A
D. (1/18) A
ANS: D

Q No: 95
If and are external and internal diameters of a circular shaft respectively, its polar moment of inertia, is
A. D4 – d4)
B. D4 – d4)
C. D4 – d4)
D. D4 – d4)
ANS: D

Q No: 96
The force in AD of the truss shown in given figure, is
A. 4.0t compression
B. 3.0t compression
C. 0.5t compression
D. 0.5t tension ANS: C

Q No: 97
length of a column of length L, having one end fixed and other end hinged, is
The equivalent
A. 2 L
B. L
C. L/2
D. L
ANS: D

Q No: 98
static equations i.e. H V M = 0, to a determinate structure, we may
By applying the
determine
A. Supporting reactions only
B. Shear forces only
C. Bending moments only
D. All the above
ANS: D

Q No: 99
A lift of weight W is lifted by a rope with an acceleration f. If the area of cross-section of the rope is A, the stress in the rope is
A. [W (1 + f/ G)]/ A
B. (1 – g/f)/A
C. [W (2 + f/G)]/A
D. [W (2 + g/f)]/A
ANS: A

Q No: 100
Co-efficient of wind resistance of a circular surface, is
A. 1/2
B. 1/3
C. 2/3
D. 3/2
ANS: C