A structure that uses trusses combines several triangular planes. The sides of each triangle are called "members." The points, or joints, are called "nodes." Your truss design includes the height and length of the trusses, and each truss's horizontal and vertical load depends on the structures they must bear. The final relevant factors in calculating the forces in your design involve the types of nodes that support them. These elements' interactions are complex, so use software to calculate them.
Visit Cornell University's truss force calculator from the first link in "Resources."
Select from the "truss type" drop-down box whether your design uses a Howe-flat, Pratt-flat, Warren or Warren-vert truss design.
Type the design's length and height in the "overall length" and "height" text boxes, respectively.
Select from the "Ra/Ha node number" the number of joints in the design that consist of direct hinges.
Select from the "Rb node number" the number of joints in the design that contain rollers.
Type the loads on each node --measured in pounds -- into each node's text boxes.
Choose the nodes whose force you want to calculate by picking them from the "Select bar between" drop-down boxes.
Click the "Update" button at the bottom of the page. The force acting on the nodes will appear in the pale green box.