CB Sowmya - Answers

For sloping ground

• Filled foundation
• Fill and cut foundation
• Stepped foundation

For coastal areas

• Pile foundation – with or without bracings
• Well foundation

To know more about foundations for different ground conditions,

https://theconstructor.org/geotechnical/construction-foundation-different-ground-conditions/7606/

The type of steel used in prestressing may be:

1. Cold worked steel
2. Stress relieving steel
3. Strain tampered steel

The following properties of the steel are appreciated:

1. High strength property of steel (min of 980 Mpa for bars)
2. Adequate ductility
3. Bendability ( for harping )
4. High bond strength (Crucial for pretensioned members because the stress transfer in the former is only through bond)
5. Less stress relaxation ( To minimize losses)
6. Less corossion

Note that the permissible stress in prestressing steel is not more than 80% of yeild strength.

Permissible stress = 0.8fy

This fy is found just like any HYSD bar by considering the 0.2% proof stress.

Waste stabilization ponds are used for treating wastewater. They are just like ones but man-made. Large ponds are constructed and they maybe link with one another to enhance the waste stabilization. These ponds make use of the principles of sedimentation, filtration, nitrification, denitrification and biodegradation. These ponds will reduce the solids, BOD, and Pathogens in the effluents. They have low operating costs and do not require electricity. If designed properly, they can be odor-free. However, they require large areas and highly accurate design and construction.

There are three types of pond

1. Anaerobic ponds
2. Aerobic ponds
3. Facultative ponds

This methods produces a low quality effluent which has to be further treated before disposal.

Bursting reinforcements are provided in Post-tensioned prestressed members or where bursting forces are prevailing. In post-tensioned members, the transfer of stress is through the anchorage blocks.

The concrete in the vicinity of the anchorage block up to the length of the larger transverse dimension of the structure is defined as the anchorage zone. This anchorage zone is very high in bursting forces. These bursting forces can be computed using the stress trajectory studies.

From the stress trajectories, bursting forces can be found and corresponding bursting reinforcements can be provided. These reinforcements are also called the end zone reinforcement or bursting links. This zone can be cast separately using a high grade of concrete to ensure safety.