For the truss shown in the figure A Indicate all the zerofor

For the truss shown in the figure: A. Indicate all the zero-force members. B. Determine the force in members HC and HG and state if the members are in tension or compression

Solution

The rule for zero force members:

Three members connected at a joint.Two of them collinear.No external force acting at the joint. The non collinear member is a zero force member.

Since the structure is symmetric can examine LHS and RHS across the cenral line.

CD and DE are colinear, if P =0, the third member DF is non colinear hence zero force.

Now looking at joint F, remove the zero force member DF, and get two colinear members GF-FEwith CF non collinear. Hence CF also zero force.

For the LHS of the structure, applied force of 2KN at B changes the conditions.

Take moments about C and A

Resolve vertically

2.)CH Zero force by defn