A steel plate d x b is sandwiched rigidly between two timber joists each D x B/2 in section. The moment of resistance of the beam for the same maximum permissible stress σ in timber and steel will be (where Young's modulus of steel is m times that of the timber).
A cantilever of length L is subjected to a bending moment M at its free end. If EI is the flexural rigidity of the section, the deflection of the free end, is