Problem 404 Roof Truss - Method of Joints

Problem 404
Determine the forces in the members of the roof truss shown in Fig. P-404.



Solution 404



In the solution, second line under the first sketch (of reaction forces at supports):

the sum of the moments about A = 2xVD=450x+(450sin30∘)(2x)

How is the last term (2x) determined?

Jhun Vert's picture

The 450 N at B was resolved into components at D. The vertical downward component is at distance 2x from A.