A flitched beam means a beam of the composite section consisting of a wooden beam strengthened by mild steel plates. Pictorial representation of flitched beam shown below. The steel and the wooden components are so connected that there will not be any slipping between them i.e the components act together acting as one beam.

Let at a distance y from the neutral axis the stress in wood and steel be $p_w$ and $P_s$ In order a slip may not occur between the steel and wood of this level the strains in Steel and wood at this level must be equal

$Strain=e=\frac{p_w}{E_w}-\frac{p_s}{E_s}$

Where $E_w$ and $E_s$ the modulus of elasticity for wood and steel.

$p_s=\frac{E_s}{E_w}.p_w$

$p_s=m.p_w$

i.e $m=\frac{E_s}{E_w}$

The ratio m is called the modular ratio between steel and wood

$M_r=\frac{1}{6}.P_w(b+2mt)d^2$

$M_r$ is the moment of resistance of the section

• A flitched beam means a beam of the composite section consisting of a wooden beam strengthened by mild steel plates. Pictorial representation of flitched beam shown below.
• The steel and the wooden components are so connected that there will not be any slipping between them i.e the components act together acting as one beam. Mr is the moment of resistance of the section.