## Prestressed Concrete Structures MCQ Set 1

1. In post tensioning, the concrete units are cast by:

a) Ducts

b) Jacks

c) Anchorages

d) Wedges

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2. After the tensioning operation, the space between the tendons and the ducts are:

a) Layered

b) Grouted

c) Cemented

d) Drilled

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3. The Freyssinet system of post tensioning anchorages was developed in:

a) 1934

b) 1935

c) 1939

d) 1936

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4. The Freyssinet system of prestressing involves the arrangement of wires of number:

a) 10

b) 14

c) 12

d) 8

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5. In Freyssinet system which element behaves as a guide?

a) Spiral spring

b) Hallow spring

c) Trapezoidal spring

d) Cable spring

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6. One of disadvantage of Freyssinet system is:

a) Stresses in the wires are not similar

b) Rapid attainment of stretching force

c) Safeguarding of wires is economical

d) Projection of plug left in concrete

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7. In Gifford-Udall system, the number of methods for prestressing members are:

a) 1

b) 2

c) 3

d) 4

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8. In Gifford-Udall system, which method involves prestressing by H.T type tendon?

a) Method 1

b) Method 2

c) Method 3

d) Method 4

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9. In Lee-McCall system, the prestressing tendons are in the form of:

a) Steel bars

b) Tension bars

c) Compression bars

d) Rings

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10. The drawback of Lee-McCall system is it cannot use:

a) Straight tendons

b) Elliptical tendons

c) Curved tendons

d) Trapezoidal tendons

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11. The method of tensioning Magnel-Balton system involves:

a) Hydraulic jack and wires

b) Hydraulic jack and bars

c) Multi strand hydraulic jack

d) Jack inserted at centre of beam

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12. Which system of prestressing is widely used in India?

a) Gifford-Udall

b) Lee-McCall

c) Magnel-Balton

d) Freyssinet

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## Prestressed Concrete Structures MCQ Set 2

1. The prestressed concrete bridge decks generally comprise

a) Precast pretensioned

b) Precast post tensioned

c) Partially pretensioned

d) Partially post tensioned

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2. The precast prestressed I and inverted T beams have been standardized by:

a) Pulverization association

b) Cement and concrete association

c) Brick association

d) Steel association

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3. The post tensioning is ideally suited for prestressing of:

a) Short span girders

b) Long span girders

c) Effective span

d) Limited span

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4. In India, a large number of long span bridges have been constructed using:

a) Simply supported beam

b) UDL

c) Point

d) Cantilever

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5. Long span continuous prestressed concrete bridges are built of which type of box girders:

a) Single celled

b) 3 celled

c) Multi celled

d) 4 celled

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6. Calculate Permissible stresses compressive stresses in concrete at transfer and working loads, as recommended given f_{ct} = 15n/mm^{2}, f_{st} = 0.8, f_{cw} is 12n/mm^{2}?

a) 13.2

b) 13.4

c) 13.8

d) 13.0

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_{ct}= 15n/mm

^{2}< 0.4f

_{ci}= (0.45×35) = 15.75n/mm

^{2}, f

_{st}ratio, ɳ = 0.80, f

_{cw}= 12n/mm

^{2}< 0.33f

_{ck}= (0.33×40) = 13.2n/mm

^{2}, f

_{u}= f

_{tw}= 0.

7. Calculate bending moment of dead load given total load = 14n/mm^{2}, Dead load bending moment dead weight of slab = 12kn/m^{2}, dead weight of w.c = 1.76kn/m^{2}, span length is 10.4m?

a) 120knm

b) 130knm

c) 190knm

d) 160knm

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^{2}, dead weight of w.c = 1.76kn/m

^{2}, total load = 14n/mm

^{2}, Dead load bending moment (m

_{g}) = (14×10.42)/8 = 190knm.

8. Calculate effective length of Road on a highway given the overall thickness is 500mm and thickness of wearing coarse is 80mm ( x is 3.6m)?

a) 4.76m

b) 34.8m

c) 2.34m

d) 1.45m

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9. Calculate the mid support section given that A_{p} = 7980mm^{2}, f_{ck} = 60n/mm^{2}, b = 800mm, f_{p} = 1862n/mm^{2}, b_{w} = 200mm, M_{u}(required) = 16865knm, D_{t} = 400mm, d = 1750mm, failure by yielding of steel?

a) 1204

b) 23402

c) 1298

d) 45367

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_{p}= 7980mm

^{2}, f

_{ck }= 60n/mm

^{2}, b = 800mm, f

_{p}= 1862n/mm

^{2}, b

_{w }= 200mm, M

_{u}(required) = 16865knm, D

_{t}= 400mm, d = 1750mm, M

_{u}= 0.9dA

_{p}f

_{p}= (0.9x1750x7980x1862) = 2340x 10

^{6}nmm = 23402 knm.

10. Calculate failure by crushing of concrete such that b_{w} is 200, d is 1750, f_{ck} is 60n/mm^{2}, b is800, D_{f} is 400?

a) 12253x106nmm

b) 15253x106nmm

c) 18253x106nmm

d) 16253x106nmm

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_{w}is 200, d is 1750, f

_{ck}is 60n/mm

^{2}, b is800, D

_{f}is 400, M

_{u}= 0.176bwd

^{2}f

_{ck}+2/3 x 0.8(b-bw)(d-0.5D

_{f})D

_{f}f

_{ck}= ((0.176x200x1750

^{2}x60)+0.67×0.8(800-200)(1750-0.5×400) 400×60)) = 18253×10

^{6}nmm.

11. Check for ultimate shear strength such that shear force, V_{u} = 2834 kn, According to IRC: 18-2000, the ultimate shear resistance of the support section uncracked in flexure loss ratio is 0.8, p is 12000×10^{3}, area is 0.88 x 10^{6}mm^{2}?

a) 11.3n/mm^{2}

b) 23.5n/mm^{2}

c) 19.9n/mm^{2}

d) 10.9n/mm^{2}

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^{3}, Area = 0.88 x 106mm

^{2}, f

_{cp}= (ɳp/A) = (0.8x12000x103/0.88×10

^{6}) = 10.9n/mm

^{2}.

12. Calculate the slope angle such that eccentricity is 750, length is 40m and stress induced is 1000n/m^{2}?

a) 0.89

b) 0.075

c) 0.054

d) 0.065

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^{2}, θ = (4e/L) = (4×750/40×1000) = 0.075.

13. Calculate spacing of a prestressed concrete T slab using 12mm diameter of two legged stirrups such that f_{c} is 415, v_{cw} = 1900kn, balance shear is 934×10^{3}?

a) 165kn

b) 345kn

c) 230kn

d) 450kn

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_{c}is 415, v

_{cw}= 1900kn, balance shear = 934kn, using 12mm diameter two legged stirrups spacing, s

_{v}= (0.87x415x2x113x1900/934×10

^{3}) = 165mm.

## Prestressed Concrete Structures MCQ Set 3

1. The prestressed concrete slab systems are ideally suited for:

a) Roofs

b) Slabs

c) Beam

d) Column

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2. The precast prestressed hollow core slabs, with or without topping is important structural element in:

a) Structures

b) Industries

c) Aquariums

d) Nurseries

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3. Prestressed pretensioned cored slabs with differ types of cavities are widely used as:

a) Floor panels

b) Tendons

c) Wall coatings

d) Reinforcements

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4. One way slabs may be supported across the entire width of the slab by means of:

a) Columns

b) Piers

c) Ridges

d) Footings

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5. The simple or continuous slabs are analyzed for:

a) Design foundation

b) Design reinforcement

c) Design moments

d) Design slab

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6. The design of a two-way-slab supported on all four sides involves the computation of:

a) Moments

b) Cross sections

c) Bending moment

d) Deformations

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7. The moment coefficients derived from the ultimate load method are generally lower in:

a) Span

b) Eccentricity

c) Strength

d) Magnitude

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8. A simple prestressed flat slab is generally supported by a network of:

a) Beams

b) Columns

c) Spans

d) Deflections

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9. The proportioning of tendons in design of prestressed concrete simple flat slab between the column and middle strips may be based on:

a) Moments

b) Codes

c) Deflections

d) Loads

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10. The design principles of continuous flat slab floors are similar to:

a) One way slab

b) Two way slab

c) Continuous

d) Deformed

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## Prestressed Concrete Structures MCQ Set 4

1. Prestressed concrete tanks have been widely used for the storage of:

a) Gas

b) Air

c) Fluids

d) Water

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2. Prestressed concrete although it is water tight, it is not:

a) Gas tight

b) Liquid tight

c) Vapour tight

d) Material tight

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3. The metal linear concept in prestressed tanks has proved to be success in case of:

a) Air tanks

b) Water tanks

c) Fluid tanks

d) Vapour tanks

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4. In the case of large tanks, the base slabs is subdivided by:

a) Water

b) Joints

c) Scale

d) Lines

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5. The nominal reinforcement provided for floor slabs stipulated by Indian standard code is not less than:

a) 0.5

b) 0.7

c) 0.15

d) 0.8

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^{2}with contraction or expansion joints and these slabs are to be cast over a layer of concrete not less than 75mm thick with a sliding layer of bitumen paper provided to prevent the bond between the screed and the floor slab.

6. In the fixed base joint the junction is between the tank wall and:

a) Slab

b) Footing

c) Beams

d) Columns

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7. When a sliding joint is made what is interposed at the junction of wall and base:

a) Rubber

b) Timber

c) Plastic

d) Soil

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8. The most common method of wire wrapping for circular tanks consists of:

a) VBR machine

b) Slump cone

c) Cassagrande apparatus

d) Traction machine

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9. Calculate minimum wall thickness given a cylindrical prestressed water tank of internal diameter 30m over a depth of 7.5m and the permissible compressive stress at transfer is 13n/mm^{2} and the maximum compressive stress under working pressure is 1n/mm^{2} and the loss ratio is 0.75?

a) 43.8

b) 82.3

c) 64.5

d) 90.4

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_{d}= 720n/mm, ɳ= 0.75, f

_{ct}= 13n/mm

^{2}, pressure is 1n/mm

^{2}T = N

_{d}/ɳf

_{ct}-f

_{min.w}= 720/ (0.75X 13) – (1) = 82.3mm.

10. Calculate circumferential prestress of a cylindrical prestressed concrete water tank given that the thickness is 12mm, loss ratio is 0.75, the maximum stress under working pressure is 1n/mm^{2}(N_{d} value is 720)?

a) 9.4n/mm^{2}

b) 5.6n/mm^{2}

c) 11.2n/mm^{2}

d) 15.2n/mm^{2}

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_{d}= 720, f

_{min.w}= 1, ɳ= 0.75, t = 120mm F

_{c}= N

_{d}/ ɳ

_{t}+ f

_{min.w}/ ɳ = 720/0.75 x 120+1/0.75 = 9.4n/mm

^{2}.

11. Calculate vertical prestressing force if wires of 5mm diameter with an initial stress of 1000n/mm^{2} are available for circumferential winding and Freyssinet cables made up of 12 wires of 8mm diameter stressed to 1200n/mm^{2} are to be used for vertical prestressing?

a) 15

b) 12

c) 8

d) 4

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^{2}, 12 wires of 8mm diameter are stressed to 1200n/mm

^{2}, f

_{c}= (12x1000x200)/(1000) = 2400kn.

12. Calculate circumferential prestress if loss ratio 0.75, thickness is 120mm, working pressure is 1n/mm^{2} and Nd is given as 840n/mm?

a) 10.75n/mm^{2}

b) 14.8n/mm^{2}

c) 12.6n/mm^{2}

d) 10.65n/mm^{2}

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_{d}= 840, f

_{min.w}= 1, ɳ= 0.75, t = 120mm, F

_{c}= N

_{d}/ ɳ

_{t}+ f

_{min.w}/ ɳ = 840/0.75×120+ 1/0.75 = 10.75n/mm

^{2}.

13. Calculate the spacing of 5mm wires having a loss ratio of 0.075, compressive stress is 10.75n/mm^{2}, 5mm diameter wires stress is 1000n/mm^{2}, 12 wires of 8mm diameter are stressed to 1200n/mm^{2}(N_{d} = 840n/mm^{2})?

a) 15.4mm

b) 11.6mm

c) 12.4mm

d) 18.5mm

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^{3}, N

_{d}= 840 S =2×840/0.075x1000x20/10.75x30x103x120) = 11.6mm.

14. Calculate the maximum vertical moment due to prestress if given self weight moment is 16.5kn/m, thickness is 0.115m and loss ratio is 0.0075?

a) 15.4

b) 21.5

c) 25.4

d) 2.6

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_{w}= 16.5kn/m, t = 0.115, ɳ= 0.075 M

_{t}= M

_{w}x W

_{t}/ ɳ 16500(0.11/0.075) = 25.4×10

^{6}nmm/m.

15. Find vertical prestressing force if characteristic strength is 8.2, wires are stressed at 1000n/mm^{2}, diameter is 150mm?

a) 1500kn

b) 1230kn

c) 4567kn

d) 8967kn

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_{c}= 8.2, stress = 1000, diameter = 150mm F = (8.2 x 1000x 150)/1000 = 1230kn.

## Prestressed Concrete Structures MCQ Set 5

1. The tendons in the pretensioning system are tensioned between:

a) Rigid anchorages

b) Hydraulic jacks

c) Concrete beds

d) Variable beams

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2. When the concrete attains sufficient strength, which elements are released?

a) Jacks

b) Casting bed

c) Tendons

d) Beams

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3. Which is one of the systems used for pretensioning?

a) Magnel-Balton system

b) Freyssinet system

c) Gifford-Udall system

d) Hoyer’s long line method

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4. Hoyer’s system of pre tensioning is generally adopted for:

a) Small scale members

b) Large scale members

c) Middle span members

d) End members

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5. The transfer of prestress of concrete is achieved by:

a) Plates

b) Rings

c) Steel bars

d) Jacks

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6. The bond of prestressing wires in Hoyer’s system can be formed by:

a) Helical crimping

b) Tangential crimping

c) Circular crimping

d) Diode crimping

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7. The Hoyer’s method of prestressing is done by:

a) Pulling out of wires

b) Pushing wires

c) Heating of wires

d) Stressing of wires

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8. The Hoyer’s system of pretensioning can be done for beams:

a) 1

b) More than 2

c) Less than 2

d) 2

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9. The Hoyer’s system of prestressing proves to be economical for:

a) Pre tensioning system

b) Post tensioning system

c) Beam casting

d) Bed casting

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10. In Hoyer’s system the projection of plugs left in concrete exceeds beyond:

a) Middle of member

b) End of member

c) First of member

d) Transfer part of member