Question

A reinforced cantilever beam of span 4 m, has a cross-section of 150 mm x 500 mm. If checked for lateral stability and deflection, the beam will

• A. (a) fail in deflection only
• B. fail in lateral stability only
• C. fail in both deflection and lateral stability
• D. satisfy the requirements of deflection and lateral stability

Answer 1

The correct option is C fail in both deflection and lateral stability

$\frac{Span}{Effectivedepth}=\frac{4000}{500}=8>7$

So the bea will fall in deflection.

For stability, the clear distance from the free end
of the cantilever the lateral restraint shall not

exceed 25b or $\frac{100b^2}{d}$ whichever is less.

Consider nominal cover = 40 mm

Effective depth = 500 - 40 = 460 mm

Clear Distance = 25 $\times$ 150 = 3750 mm

or $\frac{100\times (150{)}^2}{\left(460\right)}=4891.3mm$