# Homework Help: Trusses problem

1. Jan 7, 2016

### Zaza669

1. The problem statement, all variables and given/known data

How to find forces in bars BD CD and CE?

2. Relevant equations
Static

3. The attempt at a solution

Bd: -2.5 KN
Cd: 0.866 KN
Ce: 1.73 KN

2. Jan 12, 2016

### Staff: Admin

Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?

3. Jan 15, 2016

### Buzz Bloom

Hi Zaza:

Since no one else has posted an answer, I will offer a thought which I hope will be helpful, although I have never previously attempted to analyze this kind of problem.

Since no mention has been made about the nature of the joints between the beams, I assume that torque stresses on the joints can be ignored. You have calculated that the stress on CE is 1.73 KN. I notice that the joint G has a rolling support, and joints C and E are unsupported. I interpret this to mean that any stresses at G due to horizontal forces on AC, CE, and EG will result in G moving left or right, and this motion will relieve any horizontal stresses in AC, CE, and EG. Since any force in CE must be entirely horizontal due to symmetry, the force in bar CE is zero.

Regards,
Buzz

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