Flitched Beams

Q. Given that $m=\frac{E_s}{E_t},I_t=$ Moment of inertia of timber portion and $I_s$ = Moment of inertial of a flitched beam made of steel and timber is given by

1. $I_t+\frac{I_s}{m}$
2. $I_s+\frac{I_t}{m}$
3. $I_s+m{I}_t$
4. $I_t+m{I}_s$

Q. The figure below shows the cross-section of a flitched beam consisting of a steel plate sandwiched between two wooden blocks. The second moment of area of the composite beam about the neutral axis XX is

1. $\frac{b{h}^3}{12}+\frac{mt{h}^3}{12}$
2. $\frac{b{h}^3}{12}+\frac{t(mh{)}^3}{12}$
3. $(b+t)\frac{h^3}{12}$
4. $\frac{b{h}^3}{12}$

Q. A flitched beam shown in the figure below is subjected to a bending moment. The strain variation across the cross-section will be as in

1. 
2. 
3. 
4. 

Q. A flitched beam composed of two diffrent pieces, each having breadth b and depth d, supports an external load. This statement implies that
1. The two diffrent material are rigidly connected
2. There will be relative movement between the two materials
3. For transforming into an equivalent single-material, section under 'strength' considerations, the depth is kept constant and only the breadth is varied.

Which of the above statements are correct ?

1. 1 and 2 only
2. 1 and 3 only
3. 2 and 3 only
4. 1, 2 and 3