Why does prestressed concrete have high tensile strength?

High strength concrete is less liable to shrinkage cracks and has lighter modulus of elasticity and smaller ultimate creep strain resulting in a smaller loss of prestress in steel. Therefore high tensile steel is made for prestress concrete.

What is the density of prestressed concrete?

150 pounds per cubic foot
“Typically, concrete has a density of 150 pounds per cubic foot, which means that a block of concrete that is one foot wide, one foot long, and one foot high would weigh 150 pounds. Water has the density of only 62.4 pounds per cubic foot.”

What are the reasons for losses of strength in pre stressing concrete?

In a prestressed concrete beam, the loss is due to the following:

• Elastic shortening.
• Shrinkage of concrete.
• Creep of concrete.
• Frictional loss.
• Relaxation of steel.
• Anchorage take-up.

What are the advantages of using pre stressed concrete?

The advantages of prestressed concrete include:

• The inherent compressive strength of concrete is used to its fullest.
• The special alloy steels used to form the prestressing tendons are used to their fullest.
• Tension cracks are eliminated, reducing the risk of the steel components corroding.
• Shear stresses are reduced.

Why is high strength concrete necessary for prestressed concrete Mcq?

Explanation: The concrete in a prestressed concrete member is subjected to high bearing stresses due to anchoring at its ends and hence, high strength concrete is required to safely resist the bursting stresses at the end of the beam.

Why prestressed concrete is preferred compared to reinforced concrete?

Prestressed concrete sections are thinner and lighter than RCC sections, since high strength concrete and steel are used prestressed concrete. In prestressed concrete, whole concrete area is effective in resisting loads, unlike RCC where concrete below the neutral axis is neglected.

What is the concrete density?

The density of concrete varies, but is around 2,400 kilograms per cubic metre (150 lb/cu ft).

Why is the density of concrete important?

The mechanical properties of concrete are highly influenced by its density. A denser concrete generally provides higher strength and fewer amount of voids and porosity. So water absorption will also be less and better durability is expected from this type of concrete.

How do you compute the loss of stress due to shrinkage of concrete?

e= EcEs/=modular ratio. If the initial stress in steel is known, the percentage loss of stress due to the elastic deformation of concrete can be computed. and the methowd of curing used of high-strength concrete with low water cement ratios result in a reduction in shrinkage and consequent loss of prestress.

What are the losses in pre stressed concrete?

In pretensioned concrete, the four major sources of prestress losses are elastic shortening (ES), creep (CR), shrinkage (SH) and relaxation (RE).

What are the advantages and disadvantage of prestressed concrete?

Prestressed concrete members are able to bear reversal of stresses, impact, vibration and shock due to the absence of cracks. Practically, dead loads are neutral in a prestressed concrete beam. Consequently, the dead load weight of the structure is decreased which results in reduced consumption of materials.

Which of the following is the factor for the necessity of high strength concrete in prestressed concrete group of answer choices?

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.