1. 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
Explanation: 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.
2. 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
Explanation: 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.
3. 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
Explanation: 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.
4. Prevention of bond between the steel and concrete is known as ___________
a) Bond prestressed concrete
b) Axial prestressing
c) De bonding
d) Proof stress
Explanation: 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.
5. 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
Explanation: 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.
6. The compression in concrete and tension in steel are developed by?
a) Joint cements
b) Expansion cements
c) Water cement ratio
d) Hardened cements
Explanation: 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.
7. The distortion principle of statically indeterminate structures is subjected by ___________
a) Rotation
b) Distance
c) Placement
d) Absorption
Explanation: 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.
8. The prestressing used for arches and pavements involves the application of ___________
a) Direct forces
b) Compressive forces
c) Tensile forces
d) Axial forces
Explanation: 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.
9. The classification of prestressed concrete is based on the method of ___________
a) Designing
b) Bending moments
c) Loading
d) Stresses acting
Explanation: 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
10. 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
Explanation: 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.