Question

As per IS 456:2000 for M20 grade concrete and plain bars in tension the design bond stress ${\tau }_{bd}$=1.2 MPa. Furthur, IS 456:2000 permits this design bond stress value to be increased by 60% for HYSD bars. The stress in the HYSD reinforcing steel bars in tension, ${\sigma }_s=360$ MPa. Find the required development length, $L_d$, for HYSD bars in terms of the bar diameter, $\varphi .$_______.

• A. 46.875

Answer 1

The correct option is A 46.875
Development length,

$L_d=\frac{\sigma \times \varphi }{4{\tau }_{bd}}$

The ${\tau }_{bd}$, bond stress value is to be increased by 60% for HYSD bars.

$\therefore L_d=\frac{\sigma \times \varphi }{4{\tau }_{bd}\times 1.6}=\frac{360\times \varphi }{4\times 1.2\times 1.6}$

$L_d=46.875\varphi$