Question

How much percentage of average bond stress is increased for reinforced bars subjected to compression?

• A. 75
• B. 50
• C. 25
• D. 10

Hint:

Remember: Compression bars enjoy better confinement — hence a 25% bond stress increase is standard in design codes like IS 456.

Answer 1

The Correct Option is C

In reinforced concrete design, the bond stress refers to the adhesion between the steel reinforcement and surrounding concrete. For bars in compression, the bond behavior improves due to better confinement and contact with concrete.
According to IS 456:2000 (Indian Standard for Plain and Reinforced Concrete), when reinforcement bars are subjected to compression, the average bond stress is increased by 25% to account for this improved grip and load transfer.
This adjustment ensures the design remains safe and accounts for actual behavior under compressive forces.