Chapter 6, Problem 6.2.4P

A wood beam with cross-sectional dimensions 200 mm x 300 mm is reinforced on its sides by steel plates 12 mm thick (see figure). The moduli of elasticity for the steel and wood are E_±= 190 GPa and E_w= 11 GPa, respectively. Also, the corresponding allowable stresses are e_S= 110 MPa and e_w = 7.5 MPa,

(a)

Calculate the maximum permissible bending moment M_maxwhen the beam is bent about the- axis.

1. Repeat part (a) if the beam is now bent about its y axis.

Find the required thickness of the steel plates on the beam bent about the y axis so that M_maxis the same for both beam orientations.