Question F5.10: Determine the force in members EF, CF, and BC of the truss a......
Determine the force in members EF, CF, and BC of the truss and state if the members are in tension or compression.
Step-by-Step
From the geometry of the truss,
\begin{aligned} & \tan \phi=\frac{(9 \mathrm{ft}) \tan 30^{\circ}}{3 \mathrm{ft}}=1.732 \phi=60^{\circ} \\ & ⤹ +\Sigma M_{C}=0 \\ & F_{E F} \sin 30^{\circ}(6 \mathrm{ft})+300 \mathrm{lb}(6 \mathrm{ft})=0 \\ & F_{E F}=-600 \mathrm{lb}=600 \mathrm{lb}(\mathrm{C}) \\ & ⤹ +\Sigma M_{D}=0 \\ & 300 \mathrm{lb}(6 \mathrm{ft})-F_{C F} \sin 60^{\circ}(6 \mathrm{ft})=0 \\ & F_{C F}=346.41 \mathrm{lb}=346 \mathrm{lb}(\mathrm{T}) \\ & ⤹ +\Sigma M_{F}=0 \\ & 300 \mathrm{lb}(9 \mathrm{ft})-300 \mathrm{lb}(3 \mathrm{ft})-F_{B C}(9 \mathrm{ft}) \tan 30^{\circ}=0 \\ & F_{B C}=346.41 \mathrm{lb}=346 \mathrm{lb}(\mathrm{T}) \end{aligned}Related Answered Questions
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