Question

The effective width of a reinforced concrete T-beam flange under compression, according to IS: 456-1978, given $l_0$ is the distance between the adjacent zero moment points, b is the breadth of the rib and D is the thickness of the flange, is

• A. $\frac{l_0}{6}+B+6D$
• B. $l_0+6D$
• C. $\frac{l_0}{6}+6D$
• D. $\frac{l_0}{6}+b$

Answer 1

The correct option is A $\frac{l_0}{6}+B+6D$



For T. beam :Eff. width of compression flange
$b_f=b_w+6D_f+\frac{L_0}{6}$
$\ngtr b_w+\frac{l_2+l_2}{2}$

Where,

$L_0=$ Distance between point of zero moment in the beam.
Hence the option (a) is correct

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Note : For L-beam
$b_f=b_w+3D_f+\frac{l_0}{12}$
$\ngtr b_w+\frac{l_1}{2}$
Effective width for flanges in isolated T & L beam

For Isolated T - beam
$b_f=b_w+\frac{l_0}{\frac{l_0}{b}+4}$
$\le b$

For Isolated L-beam
$b_f=b_w+\frac{0.5l_0}{\frac{l_0}{b}+4}$
$\le$ b