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$6–33$. The Howe truss is subjected to the loading shown.  Determine the force in members $GF$, $CD$, and $GC$, and  state if the members are in tension or compression.

$6–33$. The Howe truss is subjected to the loading shown. Determine the force in members $GF$, $CD$, and $GC$, and state if the members are in tension or compression.

$6–33$. The Howe truss is subjected to the loading shown. Determine the force in members $GF$, $CD$, and $GC$, and state if the members are in tension or compression.

6–34. The Howe truss is subjected to the loading shown. Determine the force in members GH, BC, and BG of the truss and state if the members are in tension or compression.

​$ \text{Step by Step Solution​} $

$ \text{Step 1: Given Data} $

Truss with vertical loads:
\begin{array}{c}
W_A = 2\,{\rm{kN}} \\
W_H = 5\,{\rm{kN}} \\
W_G = 5\,{\rm{kN}} \\
W_F = 5\,{\rm{kN}} \\
W_E = 2\,{\rm{kN}}
\end{array}

Key dimensions:
\begin{array}{c}
AB = 2\,{\rm{m}} \\
BC = 2\,{\rm{m}} \\
CD = 2\,{\rm{m}} \\
DE = 2\,{\rm{m}} \\
CG = 3\,{\rm{m}} \\
AC = 4\,{\rm{m}} \\
AD = 6\,{\rm{m}} \\
AE = 8\,{\rm{m}}
\end{array}

$ \text{Step 2: Free Body Diagram} $

Reaction forces:
\begin{array}{c}
A_x = 0\,{\rm{kN}} \\
A_y = \text{To be determined} \\
E_y = \text{To be determined}
\end{array}

$ \text{Step 3: Reaction at E} $

Moment equilibrium about A:
\begin{array}{c}
\sum M_A = 0 \\
E_y \times 8 = 2 \times 8 + 5 \times 6 + 5 \times 4 + 5 \times 2 \\
E_y \times 8 = 16 + 30 + 20 + 10 \\
\hline
E_y = \frac{76}{8} = 9.5\,{\rm{kN}}
\end{array}

$ \text{Step 4: Section Analysis} $

Consider section FED with members:
\begin{array}{c}
F_{GF} = \text{Force in GF} \\
F_{GD} = \text{Force in GD} \\
F_{CD} = \text{Force in CD}
\end{array}

$ \text{Step 5: Angle Calculation} $

free body diagram of the truss part FED

Angle θ between GC and CE:
\begin{array}{c}
\tan \theta = \frac{3}{4} \\
\theta = \tan^{-1}\left(\frac{3}{4}\right) \\
\hline
\theta \approx 37^\circ
\end{array}

$ \text{Step 6: Force in CD} $

Moment equilibrium about G:
\begin{array}{c}
\sum M_G = 0 \\
9.5 \times 4 – 2 \times 4 – 5 \times 2 – F_{CD} \times 3 = 0 \\
38 – 8 – 10 = 3F_{CD} \\
\hline
F_{CD} = \frac{20}{3} \approx 6.67\,{\rm{kN}}\,(\rm{T})
\end{array}

$ \text{Step 7: Length FD} $

Geometric similarity:
\begin{array}{c}
\frac{GC}{CE} = \frac{FD}{DE} \\
\frac{3}{4} = \frac{FD}{2} \\
\hline
FD = 1.5\,{\rm{m}}
\end{array}

$ \text{Step 8: Force in GF} $

Moment equilibrium about D:
\begin{array}{c}
\sum M_D = 0 \\
9.5 \times 2 – 2 \times 2 + F_{GF} \cos37^\circ \times 1.5 = 0 \\
19 – 4 = -1.197F_{GF} \\
\hline
F_{GF} = \frac{-15}{1.197} \approx -12.5\,{\rm{kN}}\,(\rm{C})
\end{array}

$ \text{Step 9: Joint C Analysis} $

Vertical equilibrium:

free body diagram of the joint C
\begin{array}{c}
\sum F_y = 0 \\
F_{GC} = 0\,{\rm{kN}}\,(\text{Zero Force})
\end{array}

$ \text{Step 10: Results Summary} $

\begin{array}{c}
\text{CD: } 6.67\,{\rm{kN}}\,(\rm{T}) \\
\text{GF: } 12.5\,{\rm{kN}}\,(\rm{C}) \\
\text{GC: } 0\,{\rm{kN}}\,(\text{Inactive})
\end{array}

$ \text{Step 11: Verification} $

\begin{array}{c}
\text{Moment Check: } \sum M_A = 0 \quad \checkmark \\
\text{Force Balance: } \sum F_y = 0 \quad \checkmark \\
\hline
\text{All equilibrium conditions are satisfied}
\end{array}

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