Question

As per the provision of IS 456-2000, in the limit state method for design of beams, the limiting value of the depth of neutral axis in a reinforced concrete beam of effective depth 'd' is given as

• A. 0.53d
• B. 0.48d
• C. 0.46d
• D. Any of the above depending on the different grades of steel.

Answer 1

The correct option is D Any of the above depending on the different grades of steel.

As per IS : 456-2000
Limiting depth of NA for any grade of steel is given by
$x_{ulim}=\frac{0.0035d}{0.0055+\frac{0.87f_y}{E_s}}$
Value of x${}_{ulim}$/d for various grades of steel.

	Fe 250	Fe 415	Fe 500
$\frac{x_{u,lim}}{d}$	0.5313	0.4791	0.4560
As per IS code	0.53	0.48	0.46