## Prestressed Concrete Structures MCQ Set 1

1. The shear stress is a function of:

a) Shear force and Cross section

b) Principle stresses and elevation

c) Strain & Compatibility

d) Axial prestress & tension

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_{v}=VS/IB, τ

_{v}=shear stress, V = shear force, S = first moment of inertia, I = moment of inertia, B = width of the beam section.

2. The strength of concrete subjected to pure shear being nearly twice that in:

a) Compression

b) Tension

c) Bond

d) Anchorage

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3. The effect of maximum shear stress (τ _{v}) produces:

a) Principal tensile stresses

b) Principal compression stresses

c) Principal strain stresses

d) Principal span stresses

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_{v}) also produces principle tensile stresses on diagonal plane, the calculation of principle tensile stress resulting from direct at critical sections with or without bending and shear combined shall be carried out it is also done at the material change in width of section and should be less than 0.126(f

_{c})

^{1/2}.

4. In a prestressed concrete member, the shear stress is generally accompanied by:

a) Zone stresses

b) Anchorage stresses

c) Direct stresses

d) Bondage stresses

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5. The major principal stresses produced on diagonal plane is expressed as:

a) f_{x} + f_{y}/2

b) f_{x} + f_{y}/2 – 1/2 ((f_{x} – f_{y} )^{2} +4τ _{v}^{2} )^{1/2}

c) f_{x} + f_{y}/2 + 1/2 ((f_{x} – f_{y})^{2} +4τ _{v}^{2} )^{1/2}

d) f_{x} – f_{y}/2

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_{max}= f

_{x}+ fy/2 + 1/2 ((f

_{x}– f

_{y})

^{2}+4τ

_{v}

^{2})

^{1/2}Minor principal stress F

_{min}= f

_{x}+ f

_{y}/2 + 1/2 ((f

_{x}– f

_{y})

^{2}+4τ

_{v}

^{2})

^{1/2}F

_{x}, F

_{y}are the direct stresses in horizontal & vertical directions respectively.

6. If the direct stresses are compressive, then the magnitude of principal stresses in prestressed concrete member gets:

a) Increased

b) Decreased

c) Constant

d) Zero

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7. How many ways are there for improving the shear resistance of structural concrete members by prestressing techniques?

a) 4

b) 6

c) 3

d) 2

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8. A prestressed concrete beam span 10mm of rectangular section, 120mm wide & 300mm deep is axially prestressed on effective force of 180kn, uniformly distributed load of 5kn/m include the self weight of member. Find maximum shear stress at support?

a) 20.5n/mm^{2}

b) 1.05n/mm^{2}

c) 15.08n/mm^{2}

d) 4.05n/mm^{2}

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^{3}mm

^{2}, I = 27×10

^{7}mm

^{4}, W

_{d}= 5kn/m Shear force at support V = (5×10/2) =25kn Maximum shear stress at support, τ

_{v}= (3v/2bh) = (3/2)x(25×10

^{3}/120×300) = 1.05n/mm

^{2}.

9. A prestressed concrete beam of span 10m of rectangular section, 120mm wide & 300mm deep a curved cable having an eccentricity of 100mm at the centre of span. Find the slope of cable of support:

a) 0.08 radians

b) 0.01 radians

c) 0.04 radians

d) 0.12 radians

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10. Which type of tensioning is generally uneconomical for vertical prestressing?

a) Post tensioning

b) Pre tensioning

c) Chemical tension

d) Thermal tension

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## Prestressed Concrete Structures MCQ Set 2

1. The short term deflections are also known as:

a) Cracked

b) Un cracked

c) Instantaneous

d) Non instantaneous

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2. Which of the following is the equation given Mohr’s first theorem?

a) Area of bending moment deflection/flexural rigidity

b) Moment/flexural rigidity

c) Deflection/flexural rigidity

d) Loads/flexural rigidity

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3. Which of the following is the equation given by Mohr’s second theorem?

a) Mid span/flexural rigidity

b) Moment of area of bending moment diagram/flexural rigidity

c) End span/flexural rigidity

d) Thickness/flexural rigidity

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4. Which of the following deflections are directly obtained by Mohr’s second area theorem?

a) Simply supported beam

b) Uniformly distributed load

c) Point beams

d) Fixed beams

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5. The problems involving unsymmetrical loading can be solved by:

a) Mohr’s theorem

b) Kennedy’s theorem

c) Row’s theorem

d) Casagrande’s theorem

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6. A straight tendon at a uniform eccentricity below the centroidal axis is given as:

a) –PeL^{2}/4EI

b) –PeL^{2}/8EI

c) –PeL^{2}/14EI

d) –PeL^{2}/16EI

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^{2}/8EI, P = effective prestressing force, e = eccentricity, L = length of beam.

7. A tendon with a trapezoidal profile considering the bending moment and deflection at the centre of the beam is obtained by:

a) –Pe/6EI(2l_{1}^{2}+6l_{1}l^{2}+3l_{2}^{2})

b) –Pe/6EI(2l_{1}^{2}+6l_{1}l^{2}+3l_{2}^{2})

c) –Pe/6EI(2l_{1}^{2}+6l_{1}l^{2}+3l_{2}^{2})

d) –Pe/6EI(2l_{1}^{2}+6l_{1}l^{2}+3l_{2}^{2})

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_{1}

^{2}+6l

_{1}l

^{2}+3l

_{2}

^{2}).

8. The deflection of a beam with parabolic tendon is given as:

a) –5PeL^{2}/48EI

b) –10PeL^{2}/48EI

c) –15PeL^{2}/48EI

d) –3PeL^{2}/48EI

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^{2}/48EI, a beam with a parabolic tendon having an eccentricity e

_{1}at the centre of span and e

_{2}at the support sections and the resultant deflection at the centre is obtained as the sum of the upward deflection of a beam with a parabolic tendon of eccentricity e

_{1}+e

_{2}at the centre and zero at the supports and the downward deflection of a beam subjected to a uniform sagging bending moment of intensity pe

_{2}throughout the length, the resultant stress becomes a = PL

^{2}/48EI(-5e

_{1}+e

_{2}).

9. The deflection is computed in a way similar to sloping tendon is given as:

a) 2PL^{2}/24EI

b) 4PL^{2}/24EI

c) PL^{3}/24EI (-2e_{1}+e_{2})

d) PL^{2}/24EI (e_{1}+e_{2})

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^{2}/12EI(e

_{1}+e

_{2})) + (Pe2L

^{2}/8EI) A = (PL

^{3}/24EI (-2e

_{1}+e

_{2})).

10. The deflection due to self weight and imposed loads are:

a) 5(g+q)L^{4}/384EI

b) 5(g+q)L^{4}/384EI

c) 5(g+q)L^{4}/384EI

d) 5(g+q)L^{4}/384EI

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^{4}/384EI and deflections due to concentrated live loads can be directly computed by using Mohr’s theorem.

## Prestressed Concrete Structures MCQ Set 3

1. The estimation based on compatibility of strain of prestressed concrete involves:

a) Flexural strength

b) Tensile strength

c) Compressive strength

d) Bulking strength

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2. The distribution of concrete in strain compatibility method is:

a) Aligned

b) Curved

c) Linear

d) Bent

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3. The resistance of concrete is neglected at:

a) Tension

b) Compression

c) Shear

d) Breakage

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4. The stress distribution in the compression zone of concrete can be defined by means of:

a) Specific gravity

b) Coefficient

c) Modulus of elasticity

d) Span moment

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5. The flexural compression stress in the compressive zone follows the:

a) Block curve

b) Anchorage curve

c) Mid span

d) Stress strain curve

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_{1}& k

_{2}.

6. The stress strain characteristics of steel used as prestressing tendons is necessary for:

a) Principal computation

b) Stress computation

c) Flexural computation

d) Strain computation

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7. The number of steps to be followed in the strain compatibility method is:

a) 4

b) 7

c) 10

d) 6

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_{u}& tension T

_{u}, if the compressive and tensile forces are equal, evaluate the ultimate moment M

_{u}.

8. Who suggested a graphical version compatibility method?

a) Cornd

b) Morsch

c) Lin

d) Musy

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9. How much percentage of tensile strain is assumed at the failure of under reinforced sections?

a) 0.7%

b) 0.5%

c) 0.4%

d) 0.2%

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10. The strain compatibility method is generally applicable for:

a) Under & over reinforcement sections

b) Partially prestressed sections

c) Mid span sections

d) Fully prestressed sections

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## Prestressed Concrete Structures MCQ Set 4

1. During stress distribution in end blocks the prestressing force is applied as:

a) Concentrated force

b) Deviated force

c) Tension force

d) Torsion force

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2. The stress distribution in concrete member which is away from the anchorage and in the region of the anchorage will be:

a) Non uniform

b) Zero

c) Constant

d) Uniform

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3. The tensile stresses which tend to split the concrete are placed in the transverse direction to the:

a) Edge of member

b) Span of member

c) Axis of member

d) End of member

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4. The bursting tensile forces in end bocks with proportion P_{i} is given as:

a) F_{bst} = Pi(0.32-0.3(y_{po}/y_{o}))

b) F_{bst} = fi(0.32-0.3(y_{po}/y_{o}))

c) F_{bst} = Ti(0.32-0.3(y_{po}/y_{o}))

d) F_{bst} = πi(0.32-0.3(y_{po}/y_{o}))

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_{bst}= P

_{i}(0.32-0.3(y

_{po}/y

_{o})), y

_{po}/y

_{o}< or equal 0.3, F

_{bsr}/P

_{i}= 0.23, y

_{po}/y

_{o}> or equal 0.3, F

_{bst}/P

_{i}= 0.11.

5. The longitudinal extent of the concrete member which is rectangular in cross section is:

a) Zero

b) Equal

c) Constant

d) Unity

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6. The member within or ahead of the anchorage zone will not have any:

a) Strain

b) Stress

c) Discontinous

d) Torsion

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7. The main plate of the member in the anchorage zone has minimum edge distance of at least:

a) 2.0

b) 1.5

c) 1.8

d) 3.0

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_{b}< 0.7ϕf”c

_{i}(A/A

_{g}).

8. The anchorage zone consists of how many devices:

a) 5

b) 3

c) 2

d) 1

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9. If the centre to centre spacing of the anchorage devices will not exceed 1.5 times width then they are considered as:

a) Closely spaced

b) Gapely spaced

c) Farley spaced

d) Rectangular spaced

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10. If the anchor force points are towards the centroid, the center line of the member will not be greater than:

a) 15_{o}

b) 10_{o}

c) 20_{o}

d) 25_{o}

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_{o}and 5

_{o}respectively will be the angle of inclination of a tendon.

## Prestressed Concrete Structures MCQ Set 5

1. The prestressed member undergoes deformation due to the action of:

a) Prestressing force and flexural loads

b) Prestressing force and combined loads

c) Prestressing force and transverse loads

d) Prestressing force and tangential loads

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2. The rotation equation obtained by applying Mohr’s theorem considering a concrete beam of span l, force p, eccentricity e is:

a) θ_{p} = PeL/2EI

b) θ_{p} = PeL/4EI

c) θ_{p} = PeL/16EI

d) θ_{p} = PeL/20EI

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_{p}= Area of bending moment/flexural rigidity = PeL/2EI.

3. The cross section of a prestressed concrete beam is 100mm wide and 300mm deep and the initial stress in tendons are located at a eccentricity of 50mm is 1000n/mm^{2}, the sectional area is 100mm^{2}. Find rotation due to prestress (hogging moment)?

a) 0.00155

b) 0.00165

c) 0.00175

d) 0.00185

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^{3}/12) = 225×10

^{6}mm

^{4}Prestressing force p = (1000×100) = 10

^{5}= 100kn Rotation due to prestressing force θ

_{p}= PeL/2EI = (100×50×6×10

^{3}/2×36×225×10

^{6}) Hogging moment = 0.00185radians.

4. In the elastic range, any increase in prestressed member does not show any effect on:

a) Steel stress

b) Compressive stress

c) Bending stress

d) Flexural stress

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5. The rate of increase in stress in the tendons of a prestress concrete member depends upon:

a) Bond and breakage

b) Bond and surrounding concrete

c) Bond and elasticity

d) Bond and anchorage

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6. A prestressed concrete beam used over a span of 6m is 100mm wide and 300mm deep, live load of 4kn/m, density of concrete is 24kn/m^{3}, modulus of elasticity of concrete is 36 and steel is 210kn/mm^{2}. Find rotation due to loads(sagging moment)?

a) 0.005

b) 0.00525

c) 0.0024

d) 0.0045

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^{2}, Self weight of the beam, g = (0.1×0.3×24) = 0.72kn/m Live load on the beam (q) = 4kn/m, Total load on the beam, W

_{d}= (q+g) = (4+0.72) = 0.00472kn/mm Rotation due to prestressing force θ

_{p}= PeL/24EI = (100×50×6×10

^{3}/24×36×210×10

^{6}) Sagging moment = 0.00525radians.

7. The stress in tendons of bonded beams is:

a) α_{e} (My/I)

b) α_{e} (My/R)

c) α_{e} (My/L)

d) α_{e} (My/20)

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_{e}(My/I), α

_{e}= Modular ratio of steel to concrete, y = vertical distance of a point from centroid of concrete section, M = bending moment, I = moment of area of the section, in cases of bonded members such as pretensioned elements or post tensioned grouted members, the composite action between steel and concrete prevails and the stresses in steel are computed using the theory of composite sections up to stage of cracking.

8. The rate of increase of stress is larger in case of:

a) Bonded beams

b) Un bonded beams

c) Tensioned beams

d) Anchorage beams

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9. The development of crack widths is comparatively larger in:

a) Bonded beams

b) Un bonded beams

c) Localized beams

d) Strengthened beams

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10. Which beams are preferred mostly due to their higher flexural strength?

a) Bonded beams

b) Un bonded beams

c) Exhaustive beams

d) Extended beams