Category: Prestressed Concrete Structures Objective Questions

Prestressed Concrete Structures Multiple Choice Questions on “Nature of Losses”.

1. The initial prestress in concrete with ongoing time undergoes?
a) Reduction
b) Increment
c) Bending
d) Stressing
Answer: a
Clarification: The initial prestress in concrete undergoes a gradual reduction with time from the stage of transfer due to various causes and this is generally referred to as “loss of prestress” since there is no bending moment at the span the stress in the tendon changes only at the midspan but not at the end since concrete and steel are considered as one section after bonding the change in stresses due to the bending of this section can be calculated by using transformed section method.

2. The loss in prestress is necessary to make an estimate of ____________
a) Design
b) Loading
c) Appearance
d) Shear
Answer: a
Clarification: A reasonably good estimate of the magnitude of lines of prestress is necessary from the point of view of design, if the prestress present in the steel is considered as the force applied on the concrete at the ends and the change is stress along with length of entire beam is not concluded as change in prestress.

3. How many types of losses in prestress are observed in pretensioned member?
a) 7
b) 8
c) 4
d) 2
Answer: c
Clarification: The losses in prestress in pretensioned member are four types: Losses due to elastic deformation of concrete, Loss due to relaxation of stress in steel, Loss due to creep of concrete, Loss due to shrinkage of concrete, in pretensioned members, due to prestress present at the ends of the members the tendon bends upwards due to bending action and the tendon becomes shortened, this is not considered as loss in prestress.

4. How many types of loss in prestress are observed in post tensioned members?
a) 8
b) 10
c) 4
d) 6
Answer: d
Clarification: The loss of prestress in post tensioned members is of 6 types: Elastic deformation of concrete, relaxation of stress in steel, creep of concrete, shrinkage of concrete, slip of anchorages, friction if the tendon is not the particular line from centre of gravity of concrete section the calculation of the change in length of the beam due to bending moment will be complicated and this is considered as ordinary loss or gain 2 to 3%.

5. The frictional and anchorage slip losses are observed in ____________
a) Post tensioned members
b) Pretensioned members
c) Ruptured members
d) Tensile members
Answer: a
Clarification: The frictional losses and loss due to anchorage slip are observed in post tensioned members only because pretensioned members do not require anchorages for prestressing and in post tensioned beams which are unbounded the loss and gain of prestress depends upon the upward bending movement of the beam and the beam when loaded fully respectively.

6. The concrete members which are prestressed by providing the tensioned tendons are termed as ____________
a) Pre tensioning members
b) Internally prestressed members
c) Linear prestressed members
d) Circular prestressed members
Answer: b
Clarification: The concrete members which are prestressed by providing the tensioned tendons are termed as internally prestressed members due to bending moment in the beam is developed and the bending in the beam results in change of unit stresses, unit strains in the tendons.

7. Which of the following is a loss of prestress in post tensioned members?
a) Loss due to slip of anchorages
b) Loss due to deformations
c) Loss due to tensioning
d) Loss due to pumped concrete
Answer: a
Clarification: The loss of prestress in post tensioned members in the following is the loss of slip due to anchorages and friction, in post tensioned beams which are bounded, before grouting action the prestress in the steel is affected by the bending action of the member.

8. The sudden changes in loss of prestress may be due to ____________
a) Humidity
b) Temperature
c) Frost
d) Steel
Answer: b
Clarification: In addition to the loss of prestress in post and pre tensioning members, there may be losses of prestress due to sudden changes in temperature, especially in steam curing of pretensioned units before the bonding of tendon to the concrete, the prestress in the tendon will be influenced by the bending of the member.

9. The rise in temperature in loss of prestress causes ____________
a) Partial transfer
b) Shifting of prestress
c) Full transfer of prestress
d) Prestress elongation
Answer: a
Clarification: The rise in temperature causes a partial transfer of prestress due to elongation of the tendons between adjacent units in the long line process which may cause a large amount of creep if the concrete is not properly cured.

10. The loss of change of temperature is between ____________
a) Tension and transfer
b) Compression and prestress
c) Bending and shear
d) Principle stress and loading
Answer: a
Clarification: If there is a possibility of a change of temperature between the times of tensioning and transfer the corresponding loss should be allowed for design, due to bending of a member the prestress may vary depending upon the line of bending, position of tendons(high strength steel cables which are flexible) number of tendons which are kept at different stages and also the type of prestressing whether it is a post tensioned or pretensioned the effect of bending may be either a positive or negative in prestress.

Prestressed Concrete Structures Multiple Choice Questions on “Shear and Principal Stresses”.

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
Answer: a
Clarification: The shear distribution in un cracked structural concrete members linear deformations are assumed to be developed due to shear distribution and the shear stress in a function of shear force and cross section of the members which is given by the equations:
τ_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
Answer: b
Clarification: The effect of this shear stress is to induce principal tensile stresses on diagonal planes and in pure shear, the strength of the concrete is twice that of the strength in the tension local failures first appear in the form of diagonal tension cracks in legions of height shear stress.

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
Answer: a
Clarification: cracks are observed at the point of the development of maximum shear stresses diagonally. The effect of this maximum shear stress (τ _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
Answer: c
Clarification: In a prestressed concrete member, the shear stresses are generally accompanied by a direct stress in the axial direction of the member, and if transverse, vertical prestressing is adopted, compressive stresses in perpendicular to the axis of the moment will present in addition to the axial pre stresses.

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 _v²)^1/2
c) f_x + f_y/2 + 1/2 ((f_x – f_y)² + 4τ _v²)^1/2
d) f_x – f_y/2
Answer: b
Clarification: The major principal stress F_max = f_x + fy/2 + 1/2 ((f_x – f_y)² + 4τ_v²)^1/2
Minor principal stress F_min = f_x + f_y/2 + 1/2 ((f_x – f_y)² + 4τ _v²)^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
Answer: a
Clarification: If the direct stresses are compressive, then the magnitude of principal stresses in prestressed concrete member acts reduced considerably and therefore under working loads, these principal stresses have to be compressive in nature in order to eliminate diagonal cracks in concrete.

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
Answer: c
Clarification: In general three ways of improving the shear resistance of structural concrete members by prestressing techniques:
Horizontal or axial prestressing by inclined or sloping cables and vertical or transverse prestressing.

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/mm²
b) 1.05n/mm²
c) 15.08n/mm²
d) 4.05n/mm²
Answer: b
Clarification: A = (120×300) = 36×10³ mm², I = 27×10⁷ mm⁴, 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(25×10³ /120×300) = 1.05n/mm².

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
Answer: c
Clarification: I = 10mm, l=100mm
Slope of cable at support = (4e/l) = (4×100/10×100) = 0.04 radians.

10. Which type of tensioning is generally uneconomical for vertical prestressing?
a) Post tensioning
b) Pre tensioning
c) Chemical tension
d) Thermal tension
Answer: a
Clarification: Vertical prestressing is not generally adopted because the length of the cables being short, the loss of prestress due to anchorage slip is excessively large post tensioning is generally uneconomical for vertical prestressing due to losses of prestress encountered.

Prestressed Concrete Structures Multiple Choice Questions on “Serviceability Limit States”.

1. The computation of ultimate flexural strength of under and over reinforced sections, as well as of sections is provided by ____________
a) Indian code
b) British code
c) American code
d) France code
Answer: c
Clarification: The Indian and British code methods are limited to under reinforced sections in flexure based on the effective reinforcement ratio, the American code method provides empirical relations to compute the ultimate flexural strength of under and over reinforced sections as well as of sections with compression reinforcement.

2. The strain compatibility method of analysis involves the use of ____________
a) Tension compression curves
b) Stress strain curves
c) Bending bondage
d) Elasticity curve
Answer: b
Clarification: The rigorous strain compatibility method of analysis, which involves the use of idealized stress strain curves of steel and concrete, can also be used for an accurate assessment of the flexural strength of sections with reinforcements in the tension and compression zones.

3. The current Indian, British and American codes have more or less similar provisions for the computation of ____________
a) Shear strength
b) Shear stress
c) Shear strain
d) Shear principle
Answer: a
Clarification: The current Indian, British and American codes have more or less similar provisions for the computation of the shear strength of prestressed members that fail in web – shear or flexure – shear cracking modes.

4. The primary serviceability limit state corresponds to excessive ____________
a) Compression and tension
b) Deflection and cracking
c) Shear and Friction
d) Torsion and mass
Answer: b
Clarification: Serviceability limit state corresponds to excessive deflection and cracking and it is customary in most codes to safeguard against excessive deflection under serviceability limit state, either indirectly by prescribing minimum span/depth ratio for the member or directly specifying a maximum permissible deflection expressed as a fraction of the span.

5. The permissible deflections vary from a maximum of ____________
a) Span/180
b) Span/100
c) Span/160
d) Span/40
Answer: a
Clarification: According to the American code ACI: 318-1989, the permissible deflection vary from a maximum of span/180 to a minimum of span/480 depending upon the type of member and the seriousness of damage to the adjoining structural element.

6. The short term deflections of prestressed members of class-1 and class-2 types under service loads are influenced by?
a) Length of prestressing force
b) Depth of prestressing force
c) Magnitude of prestressing force
d) Eccentricity of prestressing force
Answer: c
Clarification: Short term deflections of prestressed members of class-1 and class-2 types under service loads are influenced by: magnitude of the prestressing force and its profile, applied load and self weight of the member and flexural rigidity of the Un cracked concrete sections.

7. The limit state of cracking is important in the case of ____________
a) Partially prestressed members
b) Fully prestressed members
c) Tangential prestressed members
d) Hollow prestressed members
Answer: a
Clarification: The limit state of cracking is particularly important in the case of partially prestressed members according to Abeles, who has contributed much information about members with limited prestress.

8. The Class 1-type members are preferred for ____________
a) Block structures
b) Containment structures
c) Cracked structures
d) Aged structures
Answer: b
Clarification: No tensile stresses are permitted under service loads and hence the structure is crack-free at the working load stage and the members are often referred to as fully prestressed, requiring higher quantity of prestressing steel associated with higher cost, generally class 1 type members are preferred for containment structures housing atomic reactors, pressure pipes and in important structures where cracking at service loads is not acceptable.

9. In class 2 structures limited tensile stresses of magnitude not exceeding the modulus of rupture of concrete are permitted under?
a) Tensile loads
b) Compressive loads
c) Principle loads
d) Working loads
Answer: d
Clarification: Class 2 structures limited tensile stresses of magnitude not exceeding the modulus of rupture of concrete are permitted under working loads members are often referred to as moderately prestressed visible cracks are not permitted in this type abeles has used such structures in British railways with very satisfactory results.

10. Which type of class structure is considered as econimal?
a) Class-1
b) Class-2
c) Class-3
d) Class-4
Answer: c
Clarification: Tensile stresses of magnitude exceeding both the modulus of rupture of concrete and the visible cracking of limited width are permitted under service loads as compiled and members are referred to as partially prestressed class-3 type constitute the most economical of prestressed concrete structures due to limited prestressing forces and high tensile steel requirements.

Prestressed Concrete Structures Multiple Choice Questions on “Analysis of Composite Sections”.

1. The dimensioning of composite sections involves determining the required size of ____________
a) Precast sections
b) Precast beams
c) Composite sections
d) Prestressed beams
Answer: c
Clarification: The dimensioning of composite sections involves determining the required size of the composite section using a standard precast prestressed beam of known section properties in order to support the required design service loads.

2. What is necessary to design a precast prestressed section?
a) Eccentricity
b) Section modulus
c) Factor safety
d) Reinforcement details
Answer: b
Clarification: It may become necessary to determine the section modulus of the precast prestressed section for a composite slab of given depth and either case, formulae relating the section moduli of the precast prestressed and composite section loading on the member, permissible stresses in the concrete and loss ratio may be developed by considering various stages of loading.

3. The critical stress condition generally occurs at ____________
a) Soffit
b) Edge
c) Middle
d) Supports
Answer: a
Clarification: The critical stress condition generally occurs at the soffit of the precast prestresssed beam is calculated in order to support the required design service load calculate the overall depth of composite slab by assuming the trial depth and add the trial depth to the depth of standard prestressed beam.

4. The first two factors considered in design considerations of composite sections are ____________
a) Sectional properties and overall depth
b) Elevation properties and overall depth
c) Design properties and overall depth
d) Construction properties and overall depth
Answer: a
Clarification: The known sectional properties of the precast prestressed beam is calculated in order to support the required design service load, calculated the overall depth of composite slab by assuming the trial depth and add the trial depth to the depth of standard prestressed beam.

5. The design considerations of composite section in step 3 and step 4 are ____________
a) Alignment and forces
b) Self weight and moments
c) Area and moments
d) Deflection and moments
Answer: b
Clarification: Calculate the self weight of the precast beam and insitu concrete self weight of precast beam W = overall depth x width x unit weight of concrete, w = d x b x 24 and Calculate the moment due to self weight and live load moment due to self weight M = 0,125xwxl². Moment due to live load Ml = 0.125xBxPxL² according to the specification the permissible compressive stress in concrete = 0.5f_ct, f_ci = compressive strength of precast pretensioned member.

6. Under minimum and maximum moments the critical stresses occur at ____________
a) Edge
b) Soffit
c) Span
d) Eccentricity
Answer: b
Clarification: In Step 5 under minimum and maximum moments we calculate the critical stresses that occur at the soffit of the precast prestressed element. The stress conditions are (P_inf – M_min/_b) < P_ct
(ɳP_inf-M/Z_b-M_b/Z_b) > or equal to p_th.

7. In typical detail of expansion joint the open cell compression seal is dependant upon its ability to maintain ____________
a) Deflection
b) Loads
c) Pressure
d) Slab
Answer: c
Clarification: In typical detail of expansion joint the open cell compression seal is dependent upon its ability to maintain Pressure on the joint side walls with varying degree of stress and generally elastometric (Neoprene) compression seals for expansion joints in bridge decks and they are made of polychloroprene otherwise known as Neoprene.

8. The coupling units are used in prestressing steel for ____________
a) Joining
b) Filling
c) Looping
d) Closing
Answer: a
Clarification: The coupling units are used in prestressing steel for coupling units used for joining of high tensile wires should have an ultimate strength of not less than the individual strengths of the wires or bars being joined and welding is not permitted for joining of high tensile wires or bars.

9. The prestressing steel, sheathing and anchorages should be stored at ____________
a) Site
b) Road
c) Room
d) Bridge
Answer: a
Clarification: The prestressing steel, sheathing and anchorages should be stored at site in such in such a way as to provide them with adequate corrosion protection and after stressing the steel in the sheath, it should be provided with permanent protection as soon as possible preferably within one week and while providing protection by pressure grouting of cement, care should be taken that the neighboring cables are penetrated by grout.

10. The prestressing tendons are not grouted in the case of ____________
a) Nuclear pressure vessels
b) Earth vessels
c) Turbines
d) Glassc
Answer: a
Clarification: the prestressing tendons are not grouted in the case of nuclear pressure vessels and protection against corrosion is ensured by filling the ducts with petroleum based jelly and the unbounded tendons facilitate re tensioning operations whenever required and the force in the tendons can be checked at periodical intervals.

11. The bottom fiber of the prestressed beams is expressed as ____________
a) P_tw – M_min/Z_t
b) P_tw + M_min/Z_t
c) P_tw – Z_t/M_min
d) P_tw + Z_t/M_min
Answer: a
Clarification: The required top and bottom fibers of the precast prestressed beams are calculated in 7 step they are expressed as:
P_t > or less than (P_tw/ɳ + M/ɳZ_b + Ml/ɳZ_b‘)
P_b > or less than (P_tw – M_min/Z_t) where P_t = characteristic tensile strength of concrete (n/mm²), P_b = stress at bottom fiber (n/mm²).

12. The maximum eccentricity in the design of composite sections is given as ____________
a) e = Z_tZ_b(P_t) / A(P_bZ_t+P_tZ_b)
b) e = Z_tZ_b(P_t-P_b) / A(P_bZ_t+P_tZ_b)
c) e = Z_tZ_b(P_t+P_b) / A(P_bZ_t+P_tZ_b)
d) e = Z_tZ_b / A(P_bZ_t-P_tZ_b)
Answer: b
Clarification: The maximum eccentricity for composite sections is given in step 8 is
e = Z_tZ_b(P_t-P_b) / A(P_bZ_t+P_tZ_b) where Z_t = section modulus of the top fiber, Z_b section modulus of bottom fiber, the minimum prestressing force is given as W = A(P_tZ_b+P_bZ_t) / Z_t+Z_b.

Prestressed Concrete Structures Multiple Choice Questions on “Material Requirement”.

1. The concrete used in trusses is normally of grade ranging from __________
a) M35
b) M50
c) M40
d) M25
Answer: a
Clarification: Concrete used in trusses is normally of grade ranging from M35 to M60 which can be considered as high strength concrete and this high strength are design mixes which are used for heavy structures.

2. The requirement consists of __________
a) Aluminium bars
b) HYSD bars
c) Torsion bars
d) Wooden bars
Answer: b
Clarification: The reinforcements consists of mild steel or HYSD bars together with high tensile steel wires or cables use in the tie members and the material requirements per truss varies with the span and spans of trusses.

3. The trusses spacing for 6m prestressed bow string truss with cable reinforcement span for 18m material requirement per truss?
a) 338-433
b) 311-234
c) 829-456
d) 675-919
Answer: a
Clarification: The trusses spacing for 6m prestressed bow string truss with cable reinforcement span for 18m material requirement per truss prestressed bow string truss with cable reinforcement span 24m-steel 621-689, 30m-steel 1041-1219.

4. The polygonal built up from blocks with prestressed bottom chord having wire cable for 18m – concrete requirement per truss (m³) is?
a) 2.50
b) 2.63
c) 2.78
d) 2.00
Answer: b
Clarification: The polygonal built up from blocks with prestressed bottom chord having wire cable: for 18m – concrete requirement per truss (m³) 24m-3.85m³, 30m-5.28m³ and the difference in truss is observed for different diameters of wire cables.

5. The truss spacing 12m prestressed bow string of linear element with wire reinforcement (18m) grade of concrete (n/mm²).
a) 30- 40n/mm²
b) 10- 50n/mm²
c) 20- 70n/mm²
d) 40- 90n/mm²
Answer: a
Clarification: 24m = 30-50, 30m = 30-50, weight of truss (Kn) 18m = 7.7-9.1, 24m = 14.9-17.4, 30m = 25.5-29.8 are the different truss spacing for spans prestressed bow string of linear element with wire reinforcement for grade of concrete.

6. Calculate effective length of warehouse shed such that length is given as 2.11m and area is given as 650mm²?
a) 3.28m
b) 4.28m
c) 6.25m
d) 1.37m
Answer: d
Clarification: L = 2.11m, A = 650mm² = 0.65m²
Effective length = L_c = (0.65×2.11) = 1.37m.

7. Calculate total diameter ratio (d’/D) of reinforced concrete truss member such that the internal diameter is 40mm and external diameter is given as 200mm?
a) 0.6
b) 0.8
c) 0.2
d) 9.6
Answer: c
Clarification: d’ = 40mm, D = 200mm
d’/D ratio = (40/200) = 0.2mm.

8. Calculate moment of reinforced concrete truss such that bending moment is given as 4.3 and breadth is given as 250mm and depth is 200mm, characteristic strength of concrete is 35n/mm²?
a) 0.48
b) 0.56
c) 0.34
d) 0.23
Answer: a
Clarification: M_u = (1.5×4.3) = 6.45knm, b = 250mm, D = 200mm, f_ck = M_u = (1.5×4.3) = 6.45knm, b = 250mm, D = 200mm, f_ck = 35n/mm²,
M = M_u /f_ck b D = (6.45×10⁶/35x250x200²) = 0.48.

9. Calculate the compression moments of reinforced concrete trusses such that compression in the member is 395, characteristic strength is 35n/mm2, breadth is 250mm and depth is given as 200?
a) 0.443
b) 0.338
c) 0.654
d) 0.234
Answer: b
Clarification: P_u = (1.5×395) = 592.5kn, b = 250mm, D = 200mm, f_ck = 35n/mm²
P_u/f_ckbD = (592.5×10³/35x200x200) = 0.338.

10. Calculate minimum reinforcement of 0.8% in the section such that given breadth is 250mm, Diameter is 200m?
a) 400
b) 600
c) 500
d) 800
Answer: a
Clarification: b = 250mm, D = 200mm
Minimum reinforcement of 0.8% in the section A_s = (0.8x200x250/100) = 400mm².

Prestressed Concrete Structures Multiple Choice Questions on “Need and Terminology”.

1. The significant observations which resulted from the pioneering research on prestressed concrete were ___________
a) High strength steel and losses of prestress
b) High strength tendon and losses of creep
c) High strength bars and losses of strain
d) High strength rings and losses of shrinkage
Answer: a
Clarification: The necessity of using high strength steel, concrete and recognisation of losses of prestress due to various causes were the observations which resulted in research on prestressed concrete while high strength tendons, bars, rings are used for transmitting prestress and losses of creep, strain and shrinkage are types of loss considered in post and pretensioned members.

2. The necessity of high strength concrete in prestressed concrete is due to ___________
a) Shear and Bonding
b) Loading and Unloading
c) Cracking
d) Bending
Answer: a
Clarification: High strength concrete is necessary in prestressed concrete, as the material offers high resistance in tension, shear, bond and bearing while loading and unloading, cracking, bending actions are actions occurring at the time of transfer of concrete.

3. In the zone of anchorages the material preferred to minimize costs is ___________
a) High strength steel
b) High strength bars
c) High strength tendons
d) High strength concrete
Answer: d
Clarification: In the zone of anchorages, the bearing stresses being higher, high strength concrete is invariably preferred to minimize costs and it is less liable to shrinkage cracks, and has a higher modulus of elasticity.

4. The length of the prestressing tendon between the end of the member and the point where the steel attains its stress is called ___________
a) Anchorage
b) De bonding
c) Cracking load
d) Transmission length
Answer: d
Clarification: The length of the prestressing tendon between the end of the member and the point where the steel attains its full stress and adequate transmission length is necessary to reduce the radial forces acting on the concrete.

5. In cab cable, the curved portion of the tendon and anchors lie in ___________
a) Compression and Tension zone
b) Cracking zone
c) Tension and Compression zone
d) Loading zone
Answer: c
Clarification: A short curved tendon arranged at the interior support of a continuous beam where the anchors are in compression zone and the curved portion is in the tensile zone is called as a cab cable and it is small in size and consists of anchorages and its sides.

6. The load at which the prestressed member develops its first crack is called as ___________
a) Transfer load
b) Creep load
c) Bending load
d) Cracking load
Answer: d
Clarification: The load on the structural element corresponding to the first visible crack is called as cracking load and transfer refers to the phase in which the prestress is transferred to the concrete, transfer load occurs at pretensioned members when prestress is released from bulk heads while in post tensioned members, transfer occurs after the tensioning of tendons.

7. In circular prestressing members, the tendons are supplied in form of ___________
a) Cables
b) Bars
c) Wires
d) Rings
Answer: d
Clarification: The term circular prestressing refers to prestressing in round members, such as tanks and pipes and the members are prestressed in a circular way while the use of bar tendons with threaded anchorages reduces the possibility of pull and are used in post tensioning system, wire tendons are mainly used in post tensioning system, cables are formed by arrangement of wires or strands.

8. In case of continuous prestressed concrete members to gain continuity, splicing is done by ___________
a) Reinforcement
b) Steel
c) Concrete
d) Tendons
Answer: d
Clarification: A stretched element used in a prestressed concrete member which serves the purpose of transmitting the prestress to concrete and it may be in the form of high tensile steel wires, cables or strands.

9. The phenomena of drying process of contraction concrete refer to ___________
a) Moisture loss
b) Shrinkage of concrete
c) Drying process
d) Weight loss
Answer: b
Clarification: Shrinkage of concrete is due to moisture loss resulting in difference in volume results in contraction of concrete on drying and it is based on relative humidity, exposure time, quantity and type of aggregate, water cement ratio in the mix.

10. The ratio between the creep strain and elastic strain of concrete is defined as ___________
a) Creep ratio
b) Creep elasticity
c) Creep coefficient
d) Creep factor
Answer: c
Clarification: Creep coefficient is progressive increase in the inelastic deformation of concrete under sustained stress components and the estimation of loss of prestress due to creep of concrete is carried out by creep coefficient method.

11. The phenomena of reduction of stress in steel at a constant strain are known as ___________
a) Reduction of stress
b) Relaxation of stress
c) De bonding
d) Proof stress
Answer: b
Clarification: Relaxation of stress refers to decrease of stress in steel at constant strain, at a certain level reduction of stress in steel occurs at a constant strain in concrete member and this phenomena occurs as a result of creep in steel while the relaxation of stress in steel changes according to the variation of percentage of creep.

12. A device which helps the tendons to transmit prestress to the member and maintain it for the design period is?
a) Cab cable
b) Anchorage
c) Tendon
d) Transfer
Answer: b
Clarification: Anchorage is the term used to denote a device which helps the tendons to transmit prestress to the member and maintain it for the design period, generally used to enable the tendon to impart and maintain prestress in concrete and the commonly used anchorages are Freyssinet, Magnel, Balton, Gifford-udall, Leon hardt etc.

13. Which of the following type of prestress applied to concrete in which tensile stresses to a limited degree are permitted is known as ___________
a) Moderate prestressing
b) Partial prestressing
c) Full prestressing
d) Axial prestressing
Answer: b
Clarification: Partial prestressing refers to the prestressing of concrete members in which some flexural cracking is allowed at full service load and an additional tensile reinforcement is also provided to achieve adequate bending strength.

14. Prevention of bond between the steel and concrete is known as ___________
a) Bond prestressed concrete
b) Axial prestressing
c) De bonding
d) Proof stress
Answer: c
Clarification: Prevention of bond between the steel wire and the surrounding concrete is known as de bonding, the concrete in which prestress is imparted to concrete through bond between tendons and surrounding concrete, members in which the entire cross section of concrete has a uniform compressive prestressing is termed as axial prestressing, the tensile stress in steel which produces a strain of 0.2 percent of the original gauge length on unloading is proof stress.