# Homework Help: Statics problem - bridge made of 2 segments

1. Dec 18, 2011

### Kattik

Ʃ1. The problem statement, all variables and given/known data
Bridge consist of two identical segments M and N connected by rods as shown in the picture. Each rod makes angle of 45° with the horizontal line.
Determine the axial forces in each rod due to the load P at point G.
[URL=http://imageshack.us/photo/my-images/266/62688168.jpg/][PLAIN]http://img266.imageshack.us/img266/2156/62688168.th.jpg[/URL][/PLAIN]

2. Relevant equations
ƩFx= 0
ƩFy= 0
ƩM= 0

3. The attempt at a solution
I have tried with cutting the bridge into 2 parts to get a result. But basically I am unable to solve the problem on my own. I think it somehow involves using moments.
I would be grateful for any help.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Dec 18, 2011

### PhanthomJay

Before splitting up the bridge into 2 sections, first sum moments about the base of M (at the top of the X) and apply equilibrium equation to solve for the vertical force at the base of N, then sum forces in y direction = 0 to solve for the vertical force at the base of M. The vert force at N divides equally to each rod at N, and the vert force at divides equally to each rod at M. Solve for the rod forces as a truss, noting that the rod forces must act axially along the long axis of the rods. Then split up the bridge and similarly solve for the uppermosts rods forces. Welome to these forums.

3. Dec 18, 2011

### Kattik

Thank you for helping me. I now will try solving it using your instructions.
If I get stuck again, I may be back with my attemps at solution and pleadings for more detailed help. :)
Thanks again