Question:easy
The average permissible stress in bond for plain bars in tension is
The average permissible stress in bond for plain bars in tension is
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IS 456 provision:
\[
\boxed{
\tau_{bd,\;compression}
=
1.25\,\tau_{bd,\;tension}
}
\]
Updated On: Jul 23, 2026
- Increased by \(25\%\) for bars in compression zone
- Increased by \(60\%\) for bars in compression zone
- Decreased by \(25\%\) for bars in compression zone
- Decreased by \(60\%\) for bars in compression zone
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The Correct Option is A
Solution and Explanation
Step 1: Think about how bars behave differently in the two zones.
A bar sitting in the compression zone of concrete is surrounded by concrete that is itself being squeezed together, which presses the concrete more firmly against the bar surface.
Step 2: Connect this to bond resistance.
Better confinement around the bar means more frictional and adhesive resistance against the bar slipping relative to the concrete, so the safe bond stress that can be allowed is higher than for a bar in tension.
Step 3: Recall the exact codal allowance.
IS 456 permits this higher allowable bond stress for compression bars to be taken as 25 percent more than the value used for tension bars.
\[ \boxed{\text{Increased by 25\% for bars in compression zone}} \]
A bar sitting in the compression zone of concrete is surrounded by concrete that is itself being squeezed together, which presses the concrete more firmly against the bar surface.
Step 2: Connect this to bond resistance.
Better confinement around the bar means more frictional and adhesive resistance against the bar slipping relative to the concrete, so the safe bond stress that can be allowed is higher than for a bar in tension.
Step 3: Recall the exact codal allowance.
IS 456 permits this higher allowable bond stress for compression bars to be taken as 25 percent more than the value used for tension bars.
\[ \boxed{\text{Increased by 25\% for bars in compression zone}} \]
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