Q$2-$a$)$ Draw the influence line for the force in member $CD$ of the bridge truss shown in figure Q$2-$a$.$ Determine the maximum force $($tension or compression$)$ that can be

$1$

developed in this member due to a $72-k$ truck having the wheel loads shown. Assume the truck can travel in either direction along the center of the deck, so that half its load is transferred to each of the two side trusses. Also assume the members are pinconnected at the gusset plates. $($Hint : use method of joint to internal force in CD$)$

Figure Q$2-$a

Q$2-$b$)$ The truck shown in figure Q$2-$d has a mass of $9Mg$ and mass center at G$1,$ and the trailer has a mass of $3Mg$ and mass center at G$2.$ Determine the absolute maximum live moment developed in the bridge.

Figure Q$2-$b