Explanation: Prestressing can reduce the amount of concrete used in construction, as well as the amount of materials used and transported, while also improving durability and service life. Concrete has a high resistance to compressive loads, but it has a significantly lesser resistance to tension.

Explanation: The basic concept involved in the analysis of prestressed concrete members is concept of combined direct and bending stresses used for columns whereas principle and shear stresses are formed in case of tensioning the prestressed and reinforced structures, overhead stresses are formed while the stresses in structures goes beyond safe limit provided by different codes.

Explanation: Prestressed concrete offers pleasant appearance and durability when compared to reinforced concrete and the two structural features of prestressed concrete, namely high strength concrete and freedom from cracks, contributes to the improved durability of structure under aggressive environmental conditions.

Explanation: Prestressed concrete is used in construction of long span bridges, industrial roofs, marine structures, nuclear pressure vessels, water retaining structures, railway sleepers etc and it also has a higher modulus of elasticity and small creep strain, resulting in smaller loss of prestressing in the steel while prestressed concrete is one of the construction material in building and bridge products around the world.

Explanation: Prestressed concrete is widely used in many branches of civil engineering and building construction and in recent days it is experiencing greatest growth in the field of commercial building because of its acoustic properties and its ability to provide long open space.

Explanation: 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.

Explanation: 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.

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.

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.

Explanation: Prestressed concrete tanks have been widely used for storage of fluids, such as water, oil, gas, sewage, granular materials like cement, process liquids and chemicals, slurries and more recently cryogens water storage tanks of large capacity are invariably made of prestressed concrete recent applications include special forms of prestressed concrete tanks, which are triaxially prestressed and serve as containment vessels and biological shields for nuclear reactors.

Explanation: An overall economy in using prestressed concrete decreases the dead weight due to which the design loads and cost of foundation reduces although there is considerable saving on the quantity of materials used in prestressed concrete members in compression with reinforced concrete members, it is not much significant due to additional costs incurred for high strength concrete, tensile steel, anchorages and other hard wires required for the production of prestressed member.

Explanation: Resultant stresses in concrete at any section are obtained by superimposing the effect of prestress and flexural stresses developed due to the loads, other common types of corrosion frequently encountered in prestressed concrete construction are pitting corrosion and chloride corrosion, a critical review of the different types of corrosion of high tensile steel in structural concrete is reported.

Explanation: The percentage of steel provided, both tensioned and un tensioned taken together should be sufficient so that when the concrete in the pre compressed tensile zone cracks, the steel is in a position to bear the additional tensile stresses transferred to it by the cracking of the adjacent fibers of the concrete, thereby preventing a sudden failure of the beam due to fracture of steel in tension.

Explanation: The concept of pressure line is very useful in understanding the load carrying mechanism of a prestressed concrete section, if a prestressed concrete member is cracked, it behaves similar to that of a reinforced concrete section, in contrast to the direct method of analysis of resultant stresses at a section of a prestressed concrete beam outlined the pressure or thrust line concept can also be used to evaluate stresses.

Explanation: The bending moment at which visible cracks developed in prestressed concrete members is generally referred to as the cracking moment after the transfer of prestress to concrete, the soffit of the beam will be under compression.

Explanation: 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.

Explanation: The deflections of prestressed concrete members are influenced by the following salient features: imposed load and self weight, magnitude of the prestressing force, cable profile, and second moment of area of cross section, modulus of elasticity of concrete, shrinkage, creep, relaxation, span, and fixity conditions.

Explanation: The prestressed concrete members develop deformation under the influence of two usually opposing effects, which are the prestress effects and transverse loads and the deflections caused are to be changed first because the loss incurred due to prestress which in turn decreases the deflection and effects of creep which increases the deflection are suggested in the method for long term deflections.