Problem $5$:

A load P will be supported by a structure consisting of

a rigid bar ABCD, a polymer

$\{$:$2\mathrm{.}8\frac{{10}^{-6}}{}F]$ bar $(1)$ and an aluminum alloy $[E=$

$10,000$ksi,$=12\mathrm{.}5\frac{{10}^{-6}}{}F]$ bar $(2),$ as shown. Each

bar has a cross$-$sectional area of $2\mathrm{.}00i{n}^2.$ The bars are

unstressed when the structure is assembled at $30F.$

After a concentrated load of $P=30$kips is applied and

the temperature is increased to $150F$ :

a$.$ Determine the normal stresses in bars $(1)$ and $(2).$

Draw a stress element for a point on each member,

showing its axial stress. Include coordinate axes

and label the stress, showing proper direction and

magnitude. Also show the location of the stress

elements on the diagram at right $($or your own$).$

b$.$ Determine the vertical deflection of joint $D.$