ANS:D - high strength concrete and high tensile steel

In a prestressed member, it is advisable to use high strength concrete and high tensile steel. Prestressed concrete works by introducing compressive stresses into the concrete before it is subjected to any external loads. This is typically achieved by pre-tensioning or post-tensioning the reinforcement (usually high tensile steel) within the concrete member. The high tensile strength of the steel allows it to withstand the tensile forces induced during the prestressing process. Using high strength concrete alongside high tensile steel offers several advantages:

1. Improved Load Capacity: High strength concrete can withstand higher compressive forces, allowing for a more efficient transfer of prestressing forces and enabling the member to carry higher loads.
2. Reduced Member Size: With high strength concrete and steel, designers can achieve the required strength with smaller member sizes, leading to more economical designs and reduced material usage.
3. Enhanced Durability: High strength concrete typically exhibits improved durability properties, such as reduced permeability and better resistance to environmental factors, which can increase the longevity of the structure.
4. Better Crack Control: High strength concrete helps control cracking, which is essential for maintaining the integrity and aesthetics of the structure.
5. Optimized Structural Performance: The combination of high strength concrete and high tensile steel allows for the design of more efficient and structurally sound prestressed members, ensuring reliable performance under various loading conditions.