020301g

Question 1

The portion of the concrete normally in tension is designed so that tendons or cables will exert enough force to keep the entire member in ________.

Answer 1

Compression

Question 2

The top edge of a simple beam is in high compression. T or F

Answer 2

T

Question 3

Why is pre-stressed concrete useful in adverse climate conditions?

Answer 3

Harmful cracks are eliminated so pre-stressed members do not permit the passage of water or possible contaminates.

Question 4

Is the quantity of reinforcement reduced in pre-stressed concrete?

Answer 4

Yes. By 10-60%

Question 5

What causes concrete to become a weak, undesirable building material?

Answer 5

Concrete is a brittle material that develops stress cracks when tensile forces are applied.

Question 6

What is done to concrete to enable it to withstand tension forces?

Answer 6

Add a reinforcement material such as rebar

Question 7

How is pre-stressed concrete different than rebar-reinforced concrete?

Answer 7

Pre-stressed allows little to no tensile forces to be developed.

Question 8

Explain how pre-stressing keeps the entire member in compression.

Answer 8

Tendons are stretched and anchored at both ends. As the tendons try to return to their original length, the concrete adjacent is pulled together, keeping it in compression.

Question 9

What are the advantages of pre-stressed concrete over normal reinforced concrete?

Answer 9

1. Elimination of cracks, allowing it to be used in adverse climate conditions
2. Less visible cracks
3. Reduction in cross-sectional area, which reduces the weight and height of a structure.
4. Longer clear spans for members are achieved.