A bending moment acting about the z axis is applied to a T-beam shown in Fig. P5.12. Tak...

A bending moment acting about the z axis is applied to a T-beam shown in Fig. P5.12. Take the thickness t= 15 mm and depth h=90 mm. Determine the width b of the flange in order that the stresses at the bottom and top of the beam will be in the ratio 3 : 1, respectively.