Category: Prestressed Concrete Structures Objective Questions

Prestressed Concrete Structures Multiple Choice Questions on “Loss Due to Shrinkage”.

1. The shrinkage of concrete in prestressed members results in ___________
a) Shortening
b) Elongation
c) Bulking
d) Stressing
Answer: a
Clarification: The shrinkage of concrete in prestressed members is due to the gradual loss of moisture which results in changes in volume, rich mixes exhibit relatively greater shrinkage than lean mixes since the contraction of the cement gel increases with the cement content, the shrinkage also depends upon the degree of hardening of the concrete at the commencement of drying and the shrinkage of concrete in prestressed members results in a shortening of tensioned wires and hence contributes to the loss of stress.

2. The shrinkage of concrete is influenced by ___________
a) Type of cement
b) Type of chemical
c) Type of admixtures
d) Type of retarders
Answer: a
Clarification: The shrinkage of concrete is influenced by the type of cement and aggregates and the method of curing used, the rate and amount of shrinkage of the structural member under ambient conditions will depend very much upon the ratio of surface area to volume of the member, as the exchange of moisture between the concrete and the atmosphere must take place through the surface.

3. Which of the following is used to reduce shrinkage of concrete?
a) High strength concrete
b) Admixtures
c) Boulders
d) Low water cement ratio
Answer: a
Clarification: The use of high strength concrete with low water cement ratios results in a reduction in shrinkage and consequent loss of prestress, aggregates of rock type having high modular of elasticity and low values of deferred strain are more effective in restraining the contraction of the cement paste and their use reduces the shrinkage of concrete.

4. The rate of shrinkage is higher at ___________
a) End
b) Surface
c) Middle
d) Edges
Answer: b
Clarification: The rate of shrinkage is higher at the surface of the member and the primary cause of drying shrinkage is the progressive loss of water from concrete, the phenomena of shrinkage being time dependant only the total anticipated or residual shrinkage strain is considered in the computation of loss of prestress to be used in design.

5. The differential shrinkage between the interior and surface of large members result in ___________
a) Surface gradient
b) Strain gradient
c) Compatibility gradient
d) Stress gradient
Answer: b
Clarification: The differential shrinkage between the interior and surface of large members may result in strain gradients leading to surface grading; it is the effect due to relative deformation caused by the shrinkage of cast in situ concrete and combined action of shrinkage plus creep in the prestressed concrete.

6. Which curing is adopted in case of pretensioned members to prevent shrinkage?
a) Surface curing
b) Edge curing
c) Moist curing
d) Total curing
Answer: c
Clarification: In the case of pretensioned members, generally moist curing is resolved to in order to prevent shrinkage until the time of transfer, the magnitude of relative strain and the stresses induced depend on the concrete composition and surrounding environment to which the composite member is exposed.

7. After the transfer of prestress, the total residual shrinkage will be larger in case of ___________
a) Pretensioned members
b) Post tensioned members
c) Chemical tensioned members
d) Biological tensioned members
Answer: a
Clarification: The total residual shrinkage strain will be larger in pretensioned members after transfer of prestress in comparison with post tensioned members, where a position of shrinkage will have already taken place by the time of transfer of stress.

8. Which of the following Indian standard code is recommended for the loss of prestress due to shrinkage?
a) IS: 1445
b) IS: 1343
c) IS: 1210
d) IS: 1550
Answer: b
Clarification: The Indian standard code IS:1343 is recommended for the loss of prestress due to the shrinkage of concrete, individual shrinkage strains are evaluated from British code BS 8110 the shrinkage stresses are calculated.

9. The loss of prestress due to shrinkage is obtained by multiplying ___________
a) Shrinkage strain and modulus of elasticity
b) Principal stress and durability of concrete
c) Curing and grade of concrete
d) Compression and tension
Answer: a
Clarification: The loss of prestress due to shrinkage is obtained by multiplying the shrinkage strain with modulus of elasticity of steel, Δf_s = E_sh×E_s, E_s = Residual shrinkage, E_s = modulus of elasticity of steel and light weight aggregates with low modulus of elasticity may lead to higher than normal concrete shrinkage where light weight aggregates are used, the value of shrinkage should be increased by 50%.

10. The post tensioned members in dry atmospheric conditions, the shrinkage may be increased by ___________
a) 50%
b) 70%
c) 30%
d) 100%
Answer: a
Clarification: For post tensioned members in dry atmospheric conditions, the shrinkage strain may be increased by 50% however, it should not exceed the value of 300×10^-4units for pretensioned members and 2.0 x 10^-4/ log(t+2) for post tensioned members, where t is the age in days of the concrete at transfer.

11. A concrete beam is prestressed by a cable carrying an initial prestressing force of 300kn, area is 300mm2. Calculate the percentage of loss of stress due to shrinkage in pretensioned members?
a) 6.3%
b) 5.3%
c) 4%
d) 2.3%
Answer: a
Clarification: Initial stress in wires = (300×10³/300) = 1000n/mm²,
If the beam is pretensioned the total residual shrinkage strain = 300×10^-6,
Loss of stress = (300×10^-6)(210×10³) = 63n/mm², % loss 0f stress = (63×1000/100) = 6.3%.

Prestressed Concrete Structures Multiple Choice Questions on “Design of Shear Reinforcement”.

1. The ultimate shear resistance for any given section, vc should be least of values __________
a) v_cw and v_cf
b) v_ew and v_ef
c) v_rw and v_rf
d) v_dw and v_df
Answer: a
Clarification: At any given section, the ultimate shear resistance, v_c should be the least of values v_cw and v_cf where, v_{cw = ultimate shear resistance of section cracked in web, vcf = ultimate shear resistance of section cracked in flange.}

2. What should be provided if the shear force due to ultimate load is less than the shear force of the concrete?
a) Tensile reinforcement
b) Shear reinforcement
c) Principle reinforcement
d) Compressive reinforcement
Answer: b
Clarification: When V the shear force due to ultimate loads is less than the shear force of the concrete v_c, the shear force which can be carried by the concrete, a minimum shear reinforcement should be provided in the form of stirrups with spacing.

3. The spacing provided for shear reinforcement is given as __________
a) S_v = (A_sv0.87f_y/0.4b)
b) (A_sv0.91f_y/0.4b)
c) (A_sv0.12f_y/0.4b)
d) (A_sv0.23f_y/0.4b)
Answer: a
Clarification: The spacing provided for shear reinforcement S_v = (A_sv0.87f_y/0.4b), S_v = spacing of stirrups along the length of member, A_sv = cross sectional area of stirrup legs effective in shear, b = breadth (for T,I,L beams it is taken as breadth of rib, b_w).

4. When the shear force due to ultimate loads is less than 0.5 times shear force of concrete then shear reinforcement is?
a) Provided
b) Not provided
c) Made equal
d) Made zero
Answer: b
Clarification: When the shear force due to ultimate loads V is less than 0.5 times the shear force of concrete: (v < 0.5v_c)
Then no shear reinforcement is provided in the members of low importance.

5. When v > v_c condition exits, then the shear reinforcement provided includes which extra terms than actual spacing equation?
a) f_y, d_t, v, v_c
b) f_t, d_t, v, v_c
c) d_t, v, v_c
d) f_e, d_t, v, v_c
Answer: a
Clarification: When V exceeds V_c shear reinforcement is required conforming to the relation (V > V_c)
The extra terms used are f_y , d_t, v, v_c these are included in the spacing equation S_v
S_v = (A_sv0.87f_ydt / V-V_c).

6. The term dt in the spacing equation is termed as __________
a) Lowest value of depth
b) Neutral value of depth
c) Highest value of depth
d) Peak value of depth
Answer: c
Clarification: When v > v_c, the spacing provided in that:
d_t is the highest value of depth from the extreme compression fiber to longitudinal bars and depth from extreme compression fiber to centroid of tendons.

7. The spacing of stirrups for maximum shear stress is __________
a) 0.9d_t
b) 0.10d_t
c) 0.12d_t
d) 0.7d_t
Answer: d
Clarification: The spacing of stirrups should exceed neither 0.75d_t nor 4 times the web thickness of flanged members, for maximum shear stress the spacing of stirrups:
S_v > 0.75d_t = > x web thickness.

8. The maximum spacing (S_v)_max is provided for the condition is?
a) V > 1.8V_c
b) V > 1.5V_c
c) V > 2.0V_c
d) V > 3.5V_c
Answer: a
Clarification: When V exceeds 1.8V_c, the maximum spacing should be reduced to 0.5d_t, the lateral spacing of the individual legs of the stirrups provided at a cross section should not exceed 0.75d_t, if V > 1.8V_c, the maximum spacing is:
(S_v) max = 0.5 d_t.

9. The maximum shear stress value for M₃₅ and M₅₀ is?
a) 3.5 and 4.0
b) 3.7 and 4.6
c) 3.8 and 6.0
d) 4.2 and 4.0
Answer: b
Clarification: The maximum shear stress value for M₃₅ grade concrete is 3.7n/mm², the maximum shear stress value for M₅₀ grade concrete is 4.6n/mm², M₃₀ grade concrete is 3.5n/mm², M₄₀ grade concrete is 4.0n/mm², M₄₅ grade concrete is 4.3, M₅₅ grade concrete is 4.8n/mm².

10. The section should be redesigned if the nominal shear stresses __________
a) Exceeds the given values
b) Equal
c) Zero
d) Constant
Answer: a
Clarification: When the nominal shear stress, v/bd exceeds the maximum permissible shear stress values for the particular grades of concrete like M-30, M-35, M-40, M-45, M-50, M-55 and above then the section should be redesigned (this is according to table of maximum shear stress(n/mm²) (IS: 1343-1980).

Prestressed Concrete Structures Multiple Choice Questions on “Principles of Dimensioning”.

1. The design values of the resistance must equal or exceed the sum of ____________
a) Design deflection
b) Design loads
c) Design bars
d) Design cross section
Answer: b
Clarification: In the design of prestressed concrete member, the minimum required resistance is predetermined for certain limit states such as collapse, deflection and cracking for each of these, the design values of the resistance must equal or exceed the sum of the design loads obtained by multiplying the specified characteristic loads by the appropriate partial safety factors.

2. The design strength of the material being known, the problem generally reduces to the determination of ____________
a) Dimensions
b) Displacements
c) Parameters
d) Length
Answer: a
Clarification: The design strength of the material being known, the problem generally reduces to the determination of suitable dimensions for the member, that is the cross sectional details followed by the design of prestress required and the corresponding eccentricity and area of reinforcement for the section.

3. The trial and error method of assuming a certain section and checking its resistance is often ____________
a) Easy method
b) Time consuming
c) Reverse method
d) Direct method
Answer: b
Clarification: The trial and error method of assuming a certain section and checking its resistance using the appropriate design formula is often time consuming since a section satisfying the requirements at the serviceability limits may be deficient at the limit state of collapse.

4. A direct method for computing the leading dimensions of a section is often feasible as in the case of ____________
a) Pure flexure
b) Partial flexure
c) Total flexure
d) Unpure flexure
Answer: a
Clarification: The direct method for computing the leading dimensions of a section is feasible in case of pure flexure where the necessary effective depth and breadth of the compression face are controlled mainly by the collapse limit states.

5. In the case of flanged member on the basis of collapse the width and depth of the compression flange is?
a) Constant
b) Zero
c) Fixed
d) Increased
Answer: c
Clarification: In the case of flanged member on the basis of collapse the width and depth of the compression flange is, while the thickness of the web is based on ultimate shear or a practical consideration of having curved cables with minimum cover requirements.

6. The minimum prestressing force required and the corresponding eccentricity are controlled by the serviceability limit states at which the stresses are not to exceed the ____________
a) Permissible values
b) Constant
c) Zero
d) Limited values
Answer: a
Clarification: The minimum prestressing force required and the corresponding eccentricity are controlled by the serviceability limit states at which the stresses are not to exceed the Permissible values are these values are permitted or limited to a certain extent.

7. The limit states of deflection rarely influence the design of prestressed members?
a) Class 4
b) Class 3
c) Class 1 and 2
d) Class 5
Answer: c
Clarification: The limit states of deflection rarely influence the design of prestressed members Class 1 and 2 since the members will be normally uncracked at service loads and in addition a pre camber will be provided by the initial upward deflection due to the prestress.

8. In case of member subjected to axial tension, the concrete section and the minimum prestress are mainly controlled by?
a) Permissible stress
b) Transverse stress
c) Strain
d) Principle stress
Answer: a
Clarification: In case of member subjected to axial tension, the concrete section and the minimum prestress are mainly controlled by Permissible stress at the service loads and in some cases (walls of tanks) by practical considerations.

9. The dimensioning of prestressed members subjected to axial load and bending is governed by ____________
a) Permissible stresses
b) Neglected stresses
c) Allowable stresses
d) Ranged stresses
Answer: c
Clarification: The dimensioning of prestressed members subjected to axial load and bending is governed by stress condition equations formulated for the opposite extreme faces of the section or by the aid of design charts for the different cases of members with uniform or non uniform prestress.

10. The required cross sectional dimensions and the prestress may be determined by solving ____________
a) Stress conditions equations
b) Multiple equations
c) Single equations
d) Unique equations
Answer: a
Clarification: Stress condition equations formulated for the opposite extreme faces of the section or by the aid of design uniform or non uniform prestress are solved for determining required cross sectional dimensions and the prestress.

Prestressed Concrete Structures Multiple Choice Questions on “Analysis of Achieving Continuity”.

1. To develop continuity the short and straight tendons may be used over the ____________
a) Spans
b) Ridges
c) Supports
d) Edges
Answer: c
Clarification: Continuity in prestressed concrete construction is achieved by using curved or straight cables which are continuous over several spans and it is also possible to develop continuity between two precast beams by using cap cables alternatively short straight tendon may be used over the supports to develop continuity between two precast prestressed beams.

2. Based on method of construction, continuous beams may be classified into __________
a) 3 types
b) 2 types
c) 5 types
d) 4 types
Answer: b
Clarification: Based on the method of construction continuous beams may be classified as fully continuous beams in which tendons are generally continuous from one end to the other and particularly continuous where each span is first precast as a simple bend and the elements are assembled to form a continuous member by using cap cables or short tendons over the supports.

3. The primary moment is the apparent bending moment at a __________
a) Section
b) Span
c) Cross section
d) Equal distance
Answer: a
Clarification: The primary moment is the apparent bending moment at a section in a statically indeterminate structure due to the actual eccentricity of the tendons from the centroid axis and primary moment at every cross section of the two span continuous beams is Pe as it is a hogging moment.

4. The secondary moment is also known as __________
a) Parallel bending moment
b) Eccentric bending moment
c) Parasitic bending moment
d) Elliptical bending moment
Answer: c
Clarification: The secondary moment also known as parasitic bending moment are additional moments induced at a section of a statically indeterminate structure due to the redundant reactions developed as a consequence of prestressing the structure and the variation of secondary moment is a two span continuous beam prestressed by a straight eccentric tendon.

5. The resultant moment is a section of __________
a) Determinate prestressed structure
b) Indeterminate structure
c) Hollow structure
d) Transverse prestressed structure
Answer: b
Clarification: The resultant moment at a section of an indeterminate prestressed structure is the sum of primarily and secondary moments:
Resultant moment = (Determinate moment +Secondary moment).

6. The resultant thrust line in a two span continuous beam is prestressed by a __________
a) Trapezoidal cable
b) Straight cable
c) Bent cable
d) Parabolic cable
Answer: d
Clarification: The resultant thrust line in a two span continuous beam prestressed by a parabolic cable with zero eccentricity at all the supports and if tendon profile is made to coincide with the resultant thrust line, the redundant reactions are completely eliminated and the cable may be considered as concordant.

7. A Transformation profile is any tendon profile consisting of __________
a) Parallel lines
b) Straight lines
c) Bent lines
d) Transverse lines
Answer: b
Clarification: A transformation profile is any tendon profile consisting of straight lines between the rigid supports and having zero eccentricity at simple end supports and a tendon following such profile will produce support reactions and uniform longitudinal compression but bending moments.

8. How many common methods are there for analyzing statically indeterminate prestressed structures?
a) 4
b) 5
c) 3
d) 2
Answer: c
Clarification: There are several methods for analyzing statically indeterminate prestressed structures to compute the secondary moments that develop from prestressing the structure and the commonly used methods are based on the principles of three moment theorem, consistent deformation and tendon reaction and the methods in b and c are also generally referred to as the flexibility influence coefficient method and the method of equivalent loads respectively and the merits and demerits of these methods and their suitability for given cases are outlined with the help of examples.

9. Which diagram is considered in three moment method analysis of secondary moments?
a) Stress strain diagram
b) Bending moment diagram
c) Pressure line diagram
d) Tee beam diagram
Answer: b
Clarification: The classical method of linear structural analysis such as the three or four moment theorem can be conveniently used to analyze the second moments developed in a continuous prestressed concrete structure and in this method, the free bending moment diagram to be considered is that due to the primary moment represented by the tendon profile with the longitudinal axis of the member as the horizontal axis.

10. The simplified form of moment equation is given by __________
a) M_ab+2M_ba+2KM_bc+KM_cb = K_ba+KK_bc
b) M_ab+2M_ba+2KM_bc = K_ba+KK_bc
c) M_ab+2M_ba = K_ba+KK_bc
d) M_ab = K_ba+KK_bc
Answer: a
Clarification: The simplified form of moment equation is given by: Mab+2Mba+2KM_bc+KM_cb = K_ba+KK_bc depending upon the degree of indeterminacy of the structure a suitable number of equations are formulated and then solved to evaluate the secondary moments and the resultant moment at any section is computed as the sum of primary and secondary moments and this method can also handle members of variable cross section along the length of the structure.

11. The tendon reaction method is based on the principle of __________
a) Equivalent tendon placing
b) Replacing the tendons
c) Tendons
d) None of the mentioned
Answer: b
Clarification: The tendon reaction method, suggested by Guyon, for analyzing statically indeterminate prestressed structure is based on the principle of replacing the tendon by an equivalent system of loads acting on the concrete member which corresponds to the reactions exerted by the tendon concrete.

12. The analysis of indeterminate structure supporting the equivalent loading directly yields the __________
a) Span moments
b) End moments
c) Resultant moments
d) Strain moments
Answer: c
Clarification: It is important to note that the analysis of the indeterminate structures supporting the equivalent loads directly yields the resultant moments consequently, the secondary moments, if required are obtained as the difference of the resultant and primary moments at every cross section of the structure.

13. In statistically indeterminate prestressed concrete structures it is possible to make simple modification to __________
a) Predetermined tendon profile
b) Elongated tendon profile
c) Collapse tendon profile
d) Ridge tendon profile
Answer: a
Clarification: In statistically indeterminate prestressed concrete structures it is possible to make simple modification to Predetermined tendon profile without altering the pressure line I the members this is an important property of continuous prestressed beams first enunciated by Guyon as follows: In a continuous prestressed beam, if the tendon profile is displaced vertically any of the intermediate supports by any amount but without altering its intrinsic shape between the supports, the resultant line of thrust is unchanged.

14. The axial contraction in case prestressed structures does not influence __________
a) Force and Moment
b) Reactions and moment
c) Deflection and moments
d) Area and moments
Answer: b
Clarification: In case of prestresssed structures comparing unidirectional members, such as continuous beams, the axial contraction due to the effect of prestressing does not significantly influence the force and moment in the continuous structure.

15. In structure like portal frames prestressing of transform results in __________
a) Tensile contraction
b) Axial contraction
c) Compression
d) Principle contraction
Answer: a
Clarification: In structures like portal frames with members in different directions, prestressing of transform results in an axial contraction, which in turn introduced tertiary moments in the frames due to the lateral displacement of the junction of the transform and column members.

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

1. Based on experimental investigations, the members of truss are analyzed on assumption that the joints are _____________
a) Rollers
b) SSB
c) UDL
d) Hinged
Answer: d
Clarification: Based on theoretical and experimental investigations, it well established that the forces in the various members of the truss are analyzed on the assumption that the joint are hinged in the case os steel, reinforced concrete and prestressed concrete trusses.

2. Which action of joint does not affect the forces developed in the members?
a) Plasticity
b) Rigidity
c) Flexural
d) Ductile
Answer: b
Clarification: The rigidity of the joint does not significantly affect the forces developed in the members and hence the analysis is generally carried out on the assumption of hinged joints and the action of rigidity joint is flexible and tough enough towards the deflection.

3. The trusses are analyzed for dead, wind and ____________
a) Wave loads
b) Fire actions
c) Snow loads
d) Tensile loads
Answer: c
Clarification: The trusses are analyzed for dead, wind and snow loads applied to the joints of the top chord and the load of suspend mechanical handling facilities is applied at the panel points of bottom chord and these loads are analyzed against check for deflection for safety of structure.

4. When loads are applied to the chords the bending moment developed are determined by assuming chord as a ____________
a) SSB
b) Continuous
c) Point
d) UDL
Answer: b
Clarification: When loads are applied to the chords of a truss between the panel points and the bending moment developed are determined by assuming the chord as a continuous beam with spans equal to the distance between the joints.

5. Trusses must be analyzed for forces developed during ____________
a) Fabrication and erection
b) Twisting and lining
c) Grouting
d) Shortcrete
Answer: a
Clarification: Trusses must also be analyzed for forces developed during fabrication and erection and initial stresses developed due to the prestressing of the bottom chord members should also be considered in the design of trusses.

6. One of the functions involved in construction management is?
a) House owners
b) Tax planners
c) Land
d) Area of site
Answer: b
Clarification: Construction of any structure forms only a small part of the whole gamut of construction management and the modern approach in construction management involves several diverse functions like designers, estimators, constructors, supervisors, accountants, financial managers, corporate secretaries, tax planners working under professional managers.

7. Which methods are widely used in project works?
a) PERT
b) CRT
c) TRC
d) WRE
Answer: a
Clarification: Critical path method of project evaluation review techniques (PERT) are widely used in the management of project work and with the advent of computers, data processing, preparation of working drawings, work scheduling, materials management, controlling the various activities of the project and upgrading the various tasks have become more simpler and they can be efficiently handled with less paper works.

8. The grade of concrete used for construction of prestressed concrete structures is?
a) Heavy mix concrete
b) Design mix concrete
c) Partially mix concrete
d) Fully mix concrete
Answer: b
Clarification: The most important consideration in the construction of prestressed concrete structures is the design, production and control of high strength concrete with desirable properties the minimum grade specified in the Indian standard code IS: 1343: 2005 for post tensioned concrete is M30 and for prestressed concrete work it is M40, the code also specifies the only Design mix concrete should be used to ensure the desired strength and durability.

9. The cement content limit is not permitted unless special consideration has been considered in design?
a) 300
b) 400
c) 375
d) 475
Answer: d
Clarification: The cement content exceeding 475kg/m3 is not permitted unless special consideration has been considered in design to the increased risk if cracking due to drying shrinkage in thin sections or to early thermal stresses in thick sections and the Indian standard code also prescribes the minimum cement content together with the corresponding maximum free water cement ratio for different types of cements when prestressed concrete likely to be exposed to sulphate attack.

10. What is the aim of workability is to use the lower percentage?
a) Coarse aggregates
b) Fine aggregates
c) Gravel
d) Sandstone
Answer: b
Clarification: The aim should be to use the lowest percentage of fine aggregates which is consistent with the job conditions and which will permit placing of the concrete without honey combs and finishing it to a satisfactory surface and for high strength concrete used for prestressed concrete structures, the degree of workability as categorized in Indian standard code IS: 456-2000.

Advanced Prestressed Concrete Structures Questions and Answers on “Principles and Classifications of Prestressing”.

1. Which one of the following is the basic assumption involved in designing of prestressed concrete members?
a) Plane member remains plane before and after bending
b) Variation of stresses in tensile reinforcement
c) Development of principle stresses
d) Hooke’s law is not valid for prestressing
Answer: a
Clarification: The basic assumption involved in analysis and designing of prestressed concrete members are the plane cross-section of beam remains plane before and after bending, there is no variation of stresses in the tensile reinforcement, Hooke’s law is valid for both concrete and steel.

2. The compression in concrete and tension in steel are developed by?
a) Joint cements
b) Expansion cements
c) Water cement ratio
d) Hardened cements
Answer: b
Clarification: Compression in concrete and tension in steel is developed by use of expanding cements due to its elastic property or expanding property, joint cement is an adhesive used primarily for attaching the joint tape that is placed over the beams whereas water cement ratio is the ratio of the weight of water to weight of cement used in a concrete mix.

3. The distortion principle of statically indeterminate structures is subjected by ___________
a) Rotation
b) Distance
c) Placement
d) Absorption
Answer: a
Clarification: Distortion principle of statically indeterminate structures is used by rotation or by displacement and in statistics a structure is statistically indeterminate when the static equilibrium equation are insufficient for determining the internal forces and reactions on that structure.

4. The prestressing used for arches and pavements involves the application of ___________
a) Direct forces
b) Compressive forces
c) Tensile forces
d) Axial forces
Answer: a
Clarification: The prestressing used for arches and pavements is the application of direct forces between abutments, whereas to impart the desired forces, flat jacks are used and axial force is the compression or tension force acting in a member if the axial force acts through the centroid of the member it is called concentric loading.

5. The classification of prestressed concrete is based on the method of ___________
a) Designing
b) Bending moments
c) Loading
d) Stresses acting
Answer: a
Clarification: Classification of prestressed concrete is based on the method of design like externally, internally, partial, moderate, axial, eccentric, concordant, uni-axial, biaxial, tri-axial, non distortional, linear, circular, post and pre tensioning, prestressed concrete has considerable increase resilience due to its capacity for completely recovering from substantial effects of overloading without undergoing any serious damage.

6. The concrete members which are prestressed by providing the tensioned tendons are termed as ___________
a) Externally prestressed members
b) Internally prestressed members
c) Linear prestressed members
d) Circular prestressed members
Answer: b
Clarification: The concrete member which is prestressed by providing the tensioned tendon are termed as internally prestressed members and the existing space between the edge of beam and abutments is filled with concrete using expanding cement.

7. The linear prestressing is mostly applicable for ___________
a) Bent members
b) Straight members
c) Cracked members
d) Overloaded members
Answer: b
Clarification: Linear prestressing is mostly applicable for straight members such as slabs, beams etc and the members are prestressed in a linear manner, tendons are spliced in case of continuous prestressed concrete members to gain continuity and the various types of splices used as tendons are screw connector, torpedo splices, clamp splice and wrapped splice.

8. In pre-tensioning system, after curing and hardening of concrete the reinforcement is set ___________
a) Free
b) Fixed
c) Locked
d) Jacked
Answer: b
Clarification: In pre-tensioning system, the tendons are tensioned first and then the casting of concrete is carried out and the edge of the tendon at its either side is fixed to an abutment and its other edge is pulled with the application of jack and then the reinforcements are set free after curing and hardening.

9. The method of prestressing the concrete after it attains its strength is known as ___________
a) Pre tensioning
b) Post tensioning
c) Chemical prestressing
d) Axial prestressing
Answer: b
Clarification: The method of prestressing the concrete after it attains its strength is known as post tensioning and ducts are made in the member at the time of placing the concrete, the suitability of post tensioning is good for medium to long span-insitu work, where the cost of tensioning is very less.

10. In which method the prestress is developed due to the bond between the concrete and steel?
a) Pre tensioning
b) Post tensioning
c) Thermo electric prestressing
d) Prefix beam prestressing
Answer: a
Clarification: The prestress developed in pre tensioning is due to the bond between concrete and steel tendons, a method of prestressing concrete in which the tendons are tensioned before the concrete is placed at the work site.

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