Question

A truss,as shown in the figure,is carrying 180 kN load at node $L_2$.The force in the diagonal member $M_2{U}_4$ will be

• A. 80 kN tesnsion compression
• B. 80 kN tesnsion
• C. 100 kN tesnsion
• D. 100 kN tesnsion compression

Answer 1

The correct option is C 100 kN tesnsion



$tan\theta =\frac{4}{3}$

$cos\theta =\frac{3}{5}$

6 panel @ 4 m = 24 m

$\sum M_{LO}=0$

$\Rightarrow 180\times 2\times 4-R_B\times 6\times 4=0$
$R_B=60kN$

Member $L_3{M}_2$ and $M_2{U}_4$ ar collinear

$\therefore$ force in $M_2{L}_4=0$

Using method of section,

$F_{M_2}{U}_{4}cos\theta$= $R_B$

$F_{M_2}{U}_4=\frac{60\times 5}{3}$

=100 kN tension