Zero-force member problem (Statics)

[aero_zeppelin]

Homework Statement

Determine the zero force members in the following truss

Homework Equations

- If only two members meet in an unloaded joint, both are zero-force members.
- If three members meet in an unloaded joint of which two are in a direct line with one another, then the third member is a zero-force member.

- If two members meet in a loaded joint and the line of action of the load coincides with one of the members, the other member is a zero-force member.

The Attempt at a Solution

Ok, I got 6 (there are 8 according to the solution) using the above rules:
HF, HI, OQ, QR, BC, and DE

The solution says that BE and LJ are also zero force members, but I have no clue why...

Any help please?

Thanks in advance!

 

[PhanthomJay]

Not LJ, its IJ, why? If BC is a zero force member, that should tell you something about BE (and DE).

 

[aero_zeppelin]

Ok, I had thought about IJ before but since the solution didn't mention it I didn't count it...

Now, for BE: since BC is a zero-force member, can we "ignore" it and then consider the other 3 with Rule #2?

 

[PhanthomJay]

Ok, I had thought about IJ before but since the solution didn't mention it I didn't count it...

Now, for BE: since BC is a zero-force member, can we "ignore" it and then consider the other 3 with Rule #2?

yes.

 

[aero_zeppelin]

Thank you sir ;)