## Prestressed Concrete Structures MCQ Set 1

1. Which one of the following is the Indian standard regarded to the limit state of deflection:

a) IS: 1443-1950

b) IS: 1343-1980

c) IS: 1514-1941

d) IS: 1600-1948

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2. The final deflection due to all loads including the efforts of temperature, creep and shrinkage should normally exceed span up to:

a) Span/250

b) Span/300

c) Span/500

d) Span/800

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3. The deflection including the effects of temperature, creep and shrinkage occurring after the erection should not normally exceed:

a) Span/400

b) Span/350

c) Span/140

d) Span/100

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4. If the finishes are to be applied to the prestressed concrete members, the total upward deflection should not exceed:

a) Span/300

b) Span/450

c) Span/150

d) Span/350

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5. The British code specifies a maximum deflection limit of span which the sag in the member usually become noticeable is:

a) Span /130

b) Span/250

c) Span/200

d) Span/150

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6. The type of deflection of not supporting and non structural elements of flat roofs is:

a) Large deflection

b) Immediate deflection

c) Small deflection

d) Edge deflection

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7. The floors not supporting and not attached to non structural elements are damaged by:

a) Large deflection

b) Column deflection

c) Span deflection

d) Beam deflection

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8. The FIP-1984 limits for total deflection below the level of supports up to:

a) Span/200 to Span/300

b) Span/150 to Span/250

c) Span/100 to Span/50

d) Span/175 to Span/280

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9. The FIP-1984 limits for deflection that occurs after addition of partitions up to:

a) Span/200 to Span/300

b) Span/250 to Span/350

c) Span/500 to Span/1000

d) Span/170 to Span/320

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10. The French code limits the deflection of members carrying masonry and partition walls up to:

a) Span/600

b) Span/400

c) Span/500

d) Span/700

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## Prestressed Concrete Structures MCQ Set 2

1. The composite sections provide one monolithic action between:

a) Prefabricated units

b) Post fabricated units

c) Pasteurized units

d) Tensioned units

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2. The high strength prestressed units are used in which zone?

a) Compression zone

b) Tension zone

c) Span zone

d) Beam zone

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3. The Composite construction was first tries for a motorway bridge:

a) 1940

b) 1945

c) 1960

d) 1980

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4. Due to the effect of composite action sizes of precast prestressed units can be:

a) Increased

b) Reduced

c) Deducted

d) Serviced

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5. In many cases precast prestressed unit serve as:

a) Supports and dispences

b) Girders and dispences

c) Area and dispences

d) Beams and dispences

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6. The efficient utilization of material in a composite section in which the low and medium strength concrete resists:

a) Tensile forces

b) Principal forces

c) Compressive forces

d) Axial forces

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7. The combination of light weight concrete for the cast insitu slab results in reduced:

a) Live loads

b) Dead loads

c) Constant loads

d) Limited loads

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8. In case of conventional method there will be a steel beam and slab construction in which the components carries their:

a) Entire load

b) Half load

c) Span load

d) Deflection

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9. The main components of the composite beam are prestressed precast stem and:

a) A cast insitu flange

b) A cast insitu beam

c) A cast insitu slab

d) A cast insitu column

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10. To attain the composite action the precast stem and the flange is:

a) Laced together

b) Tied together

c) Keyed together

d) Cutted together

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## Prestressed Concrete Structures MCQ Set 3

1. The equivalent moment of given loading is:

a) Pe

b) 4Pe/L

c) Pe/L^{2}

d) Pe/aL

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2. The tendon profile of given equivalent loading is:

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^{2}/48EI.

3. The cable provided for the given loading is:

a) ML^{2}/8EI

b) WL^{3}/48EI

c) 5WL^{4}/384EI

d) 12WL^{4}/384EI

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^{2}and Camber provided for the cable is 5WL

^{4}/384EI.

4. The moment profile for given loading is:

a) W=Pe/aL

b) W=Pe/4aL

c) W=Pe/16aL

d) W=Pe/24aL

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^{2})WL

^{2}/24EI.

5. A rectangular prestressed beam 150 mm wide and 300mm deep is used over a effective span of 10m and the cable with zero eccentricity at the supports, linearly varying to 50mm at the centre carries an effective prestressing force of 500kn(Z=225×10^{4}). Evaluate stress due to prestressing?

a) 22.2n/mm^{2}

b) 42.2n/mm^{2}

c) 32.2n/mm^{2}

d) 52.2n/mm^{2}

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^{2}=13.5knm, Stress due to self weight = (13.5×10

^{6}/225×10

^{4}) = 6n/mm

^{2}, Stress due to prestressing = (P/A+Pe/A) = (500×10

^{3}/45×10

^{3})+(500×10

^{3}×50/225×10

^{4}) =22.22n/mm

^{2}.

6. A rectangular beam of 300mm wide and 800mm deep supports two concentrated loads of 20kn each at a span of 9m.Calculate the prestressing force and suggest a suitable cable profile if the eccentricity is 50mm?

a) 600kn

b) 500kn

c) 200kn

d) 800kn

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^{6}mm

^{3}Pe = QL/3 , P = (QL/3e) = (200×9000/3×100) = 600kn.

7. A beam of symmetrical I-section spanning 8m has a flange width of 250mm and flange thickness of 80mm, overall depth is 450mm, eccentricity of 150mm, g = 1.57kn/m, q = 2.50kn/m. Determine effective force?

a) 250

b) 217

c) 320

d) 200

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_{g}= (0.125×1.57×8

^{2}) = 12.56knm M

_{q}= (0.125×2.50×8

^{2})=20knm, Total moment M = (M

_{g}+M

_{q})=32.5knm P = (M/e) = (32.5×103/150) = 217kn.

8. The shape of the bending moment diagram results from:

a) Tendon profile

b) External loads

c) Cable profile

d) Compression

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9. When the beam supports two concentrated loads, the cable follows which profile?

a) Straight

b) Bent

c) Curved

d) Trapezoidal

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10. If the beam supports uniformly distributed load the tendon follows:

a) Straight

b) Ellipse profile

c) Random profile

d) Parabolic profile

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_{x}= p = w

_{e}l

^{2}/8h.

11. The concept of load balancing is useful in selecting the:

a) Anchorage profile

b) Bending profile

c) Tendon profile

d) Jack profile

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## Prestressed Concrete Structures MCQ Set 4

1. The width of cracks that developed in prestressed members is governed by how many factors:

a) 3

b) 4

c) 5

d) 7

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2. The formula recommended by the British code BS: 8110 – 1985 for the estimation of surface crack width W_{cr} is:

a) W_{cr} = 3a_{cr}ε_{m} / 1+2(a_{cr} – C_{min}/h-x)

b) W_{cr} = 3a_{cr}ε_{m}

c) W_{cr} = 3a_{cr}ε_{m} / 1+2(a_{cr} + C_{min}/h-x)

d) W_{cr} = 5a_{cr}ε_{m }

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_{cr}= 3a

_{cr}ε

_{m}/ 1+2(a

_{cr}– l

_{min}/h-x) is recommended by the British code BS: 8110 – 1985 for the estimation of surface crack width based on the work of beedy, a

_{cr}= distance from the point considered to the surface of the nearest longitudinal area, ε

_{m}= average strain at the level where cracking is being considered, C

_{min}= minimum cover to the tension steel, h = overall depth of member, x = neutral axis.

3. The reason for smaller crack widths in slabs under service loads is:

a) H – x is large

b) H + x is small

c) 0

d) Constant

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_{m}is a maximum at the tension face if h-x is sufficiently small for the crack width at the tension face not to exceed the permissible limit of 0.3mm, it will not exceed the limit anywhere, this is the reason for smaller crack widths in slabs under service loads, provided the thickness does not exceed about 200mm.

4. The stabilized mean crack spacing acs can be expressed as:

a) C (A_{1}/Ʃ0)

b) C (A_{1}/Ʃ8)

c) C (A_{1}/Ʃ5)

d) C (A_{1}/Ʃ7)

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_{cs}can be expressed as C (A

_{1}/Ʃ0) A

_{t}= effective concrete area in tension, Ʃ0 = sum of the circumferences of the reinforcing elements, C = empirical constant.

5. The width of cracks is influenced by:

a) Hollow stress

b) Linear stress

c) Net stress

d) Shear stress

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_{cr}is equal to the concrete cover C

_{min}equation then reduces: W

_{cr}= 3a

_{cr}ε

_{m}and Case 2: when distance a

_{cr}is large: W

_{cr}= 1.5(h-x) εmin.

6. The British and Indian standard codes on prestressed concrete maximum limiting crack for members exposed to aggressive environment is:

a) 0.1mm

b) 0.3mm

c) 0.6mm

d) 0.4mm

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7. A nano polymer range which meets wider expectations as aesthetics is known as:

a) Refit

b) Break

c) Struck

d) Collapse

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8. The construction joints should be located at points of:

a) Maximum shear

b) Minimum shear

c) Total shear

d) Average shear

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9. When the work is resumed the surfaces of the concrete previously placed should be cleaned of:

a) Ash

b) Mud

c) Dirt

d) Soil

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10. In roadway slabs, construction joints should be formed:

a) Vertical

b) Horizontal

c) Aligned

d) Loaded

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## Prestressed Concrete Structures MCQ Set 5

1. The soffit of the beam after the transfer of prestress to concrete will be under:

a) Tension

b) Compression

c) Breakage

d) Bondage

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2. The compressive and tensile stresses developed in cracking moments are due to:

a) Bending loads

b) Transverse loads

c) Tensile loads

d) Compressive loads

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3. The micro cracks develop as soon as the tensile strain in concrete exceeds about:

a) 80-100×10^{-6} units

b) 100-150×10^{-6}units

c) 150-300×10^{-6} units

d) 300-500×10^{-6} units

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^{-6}units and the parameters in concrete are influenced by various materials and their permissible values according to Indian standard codes.

4. When the loads in a concrete member are further increased than permitted, the crack widths are of an order of limit:

a) 0.01-0.02mm^{5}

b) 0.05-0.10mm^{5}

c) 0.03-0.05mm^{5}

d) 0.07-0.08mm^{5}

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^{5}and these width of cracks are considered from a value of minimum to maximum not excess till permitted.

5. A rectangular concrete beam of cross section 120mm wide and 300mm deep is prestressed by a straight cable, effective force of 180kn at an eccentricity 50, area of 36×103mm2(z=18×105mm3). Find the total stress due to prestress?

a) 10

b) 25

c) 35

d) 45

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^{3}mm

^{2}, e = 50mm, b = 120mm, d = 300mm, z = 18×10

^{5}mm

^{3}Stresses due to prestress = (p/a) = (180×10

^{3}/36×10

^{3}) = 5n/mm

^{2}, (p

_{e}/z) = (180×10

^{3}×50/18×10

^{5}) = 5n/mm

^{2}

Total stress = ((p/a)+(p_{e}/z))=(5+5) = 10n/mm^{2}.

6. A rectangular concrete beam of cross section 100mm wide and 400mm deep is prestressed by a straight cable of span 6m, imposed load is 3.14kn/m, area is 36×10^{3}mm^{2}(Z=18×10^{5}mm3). Calculate working moment assuming the self weight of concrete as 24kn/m^{3}?

a) 10.25

b) 2.25

c) 3.25

d) 4.25

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^{5}mm

^{3}, A= 36×10

^{3}mm

^{2}, G = (0.1×0.4×24) =0.96kn/m Total load W = (g+q) = (0.96+3.14) = 4.1kn/m, Maximum working moment = (0.125×4×6

^{2}) = 18.45knm (M/Z) = (18.45×10

^{6}/18×10

^{5}) = 10.25n/mm

^{2}.

7. When the tensile stresses are developed in the cracks, they are visible at:

a) Hoop stress of beams

b) Soffit of beams

c) Sagging of beams

d) Hogging of beams

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8. The cracks appear when the tensile stresses at the soffit are equal to:

a) Modulus of elasticity

b) Modulus of rupture

c) Tension modulus

d) Reinforcement modulus

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9. The widths of the cracks are influenced by:

a) Degree of bond

b) Stress

c) Strain

d) Tension

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10. The formulae for load factor against cracking is:

a) Cracking moment/Working moment

b) Cracking moment/Bending moment

c) Cracking moment/Tensile moment

d) Cracking moment/Aerial moment