Method of joints & forces between joints

AI Thread Summary
The discussion focuses on calculating stresses in truss bridge members using the method of joints, particularly when loads are applied between joints. The challenge arises from forces that do not act directly through the joints, complicating the summation of forces. Participants emphasize the need to establish equations for vertical force equilibrium at the joints adjacent to the applied load. It is assumed that members are in pure tension or compression without deflections or bending moments. The reactions from the loads must be effectively transmitted through the members connected at each joint.
Shakarri
Messages
4
Reaction score
0
Part of my assignment is to find the stresses in each member of a truss bridge, but unlike the problems I have been taught before, this involves a load between the joints of the bridge. Me and my group are using the method of joints to find the forces acting through each member, the problem is that there are forces that do not act through the joints so we cannot sum them so easily. I would like to know how to set up an equation describing the vertical force on the joints beside the force.
I attached an image which should help make sense of my query. We are meant to assume that each member is in pure tension or compression i.e. there is no deflection or bending moments.
 

Attachments

  • bridge_image.png
    bridge_image.png
    4.6 KB · Views: 511
Physics news on Phys.org
If the members can sustain no deflections and the joints cannot experience bending moments, then all that can be done is to write an equation for vertical force equilibrium involving the joints on either side of the applied load. The reactions due to the loads must then be transmitted into whatever members meet at a particular joint.
 

Similar threads

Back
Top