CE 414 Prestressed Concrete Design Lesson 1

Questions and Answers

Higher water-cement ratio in the mix

Application of an initial load prior to use (correct)

Use of low-strength steel reinforcements

Use of lightweight aggregates

Increased tensile strength of the material

Decrease in shear capacity

Higher external load required to crack

Significant loss of stiffness after cracking (correct)

Decreases overall weight of the structure

Reduces the flexibility of the concrete

Increases the external load required for cracking (correct)

Eliminates the need for any reinforcing steel

Low tensile strength Signup and view all the answers

To control or eliminate tensile stresses Signup and view all the answers

Through the use of high strength steel and concrete Signup and view all the answers

Increased shear capacity compared to ordinary concrete Signup and view all the answers

Long-term corrosion of reinforcements Signup and view all the answers

Reduced overall robustness Signup and view all the answers

Tensile stresses in the concrete Signup and view all the answers

Study Notes

Prestressed concrete structures apply an initial load before use, distinguishing them from conventional reinforced concrete.
The technique aims to combat the inherent weakness of concrete in tension, addressing issues like cracking and excessive deflection.

Conventional concrete experiences tensile cracking, leading to reduced stiffness and potential durability problems.
High-strength steel is often underutilized in standard reinforced concrete applications.

Prestressing introduces pre-compression, which significantly increases the load required for cracking, enhancing overall strength and stiffness.
It allows for better control or elimination of tensile stresses, reducing the risk of cracking under service load levels.

Helps to control deflection at predetermined load levels, ensuring structural integrity.
Facilitates the effective use of high-strength steel and high-strength concrete, optimizing material benefits.

Prestressed concrete exhibits higher shear capacity than conventional reinforced concrete.
This method can also improve flexural capacity in columns, particularly in typical design regions.