Section B

Write your calculations and final answers on the sheets provided. Hand in the sheets.

Question $4(20\mathrm{.}5$ marks$)-$ use OCR page $20$&$21$ only

The truss is pin$-$supported at A and $E,$ with forces applied at joint $G,H$ and I. Members $AB,BC,CD,EG,GH$ and $HI$ are all $3m$ long. Members $BG,CH$ and $DI$ are all $4m$ long.

The figure is not to scale.

$4\mathrm{.}1$ Use the Method of Joints to calculate the forces in members CD$,$ DI$,$CI and $HI,$ and state if the members are in tension, compression or neither $($zero$-$force members$).$ Use page $20.$

$4\mathrm{.}2$ Use the Method of Sections with one sectional cut to calculate the forces in members $BCBH$ and $GH,$ and state if the members are in tension, compression or neither $($zero$-$forc members$).$ Use page $21.$

$F_y{F}_{D_1}+F_{C_1}(\frac{4}{5})-200=0$

$F_x$:$F_{H_i}+F_{C_1}(\frac{3}{5})=0$