Editing Structural analysis (section)

====Method of sections====
This method can be used when the truss element forces of only a few members are to be found. This method is used by introducing a single straight line cutting through the member whose force has to be calculated. However this method has a limit in that the cutting line can pass through a maximum of only 3 members of the truss structure. This restriction is because this method uses the force balances in the x and y direction and the moment balance, which gives a maximum of 3 equations to find a maximum of 3 unknown truss element forces through which this cut is made. Find the forces FAB, FBD and FCD in the above example

=====Method 1: Ignore the right side=====
:[[Image:Truss Structure Analysis, Method of Sections Left2.jpg|border|550x450px]]
:<math>\sum M_D=0=-5*1+\sqrt{3}*F_{AB} \Rightarrow F_{AB}=\frac{5}{\sqrt{3} }</math>
:<math>\sum F_y=0=R_{Ay}-F_{BD}\sin(60)-10=5-F_{BD}\frac{\sqrt{3}}{2}-10 \Rightarrow F_{BD}=-\frac{10}{\sqrt{3}}</math>
:<math>\sum F_x=0=F_{AB}+F_{BD}\cos(60)+F_{CD}=\frac{5}{\sqrt{3}}-\frac{10}{\sqrt{3}}\frac{1}{2}+F_{CD} \Rightarrow F_{CD}=0</math>

=====Method 2: Ignore the left side=====
:[[Image:Truss Structure Analysis, Method of Sections Right2.jpg|border|600x450px]]
:<math>\sum M_B=0=\sqrt{3}*F_{CD} \Rightarrow F_{CD}=0</math>
:<math>\sum F_y=0=F_{BD}\sin(60)+R_B=F_{BD}\frac{\sqrt{3}}{2}+5 \Rightarrow F_{BD}=-\frac{10}{\sqrt{3}}</math>
:<math>\sum F_x=0=-F_{AB}-F_{BD}\cos(60)-F_{CD}=-F_{AB}-\left(-\frac{10}{\sqrt{3}}\right)\frac{1}{2}-0 \Rightarrow F_{AB}=\frac{5}{\sqrt{3}}</math>

The truss elements forces in the remaining members can be found by using the above method with a section passing through the remaining members.