The U$-$beam $($AE$)$ shown in Figure Q$4$ is simply supported and constructed by

nailing three wooden planks. All loads are applied in plane and no out of plane

loads or moments are applied to the beam. Young's modulus of wood is

$12$GPa.

I. Draw the shear force diagram showing shear force values.

$[4/20$ marks$]$

II$.$ Determine the maximum permissible longitudinal spacing of nails for the

beam portion $BC.$ The shear capacity of a single nail is $750N.$

$[8/20$ marks$]$

III. Sketch the bending and shear stress diagrams at a section adjacent to C$.$

$[8/20$ marks$]$

Figure Q$4.$