1. The problem statement, all variables and given/known data I am trying to analyse a 3D truss problem (attached). The idea is that when you pull with a force F in the direction of the arrows, the pin in the middle will be pressed downwards, decreasing the length of p2. In general the overall structure will be consistent of a series of these in both directions. I am having some difficulties getting started with this. As far as I can tell I should be ok to only analyse the section shown in the bottom picture? 2. Relevant equations I wish to get some sort of solution that relates the length L1 and L2 to p1 and p2. 3. The attempt at a solution My first attempt at this is to use simple statics in 3D: Point at top of pin: Sum(F_y) = 0 0 = - F_(BE) - F*sin(Beta)*2 (symetry) Sum(M_top) = 0 0 = - F * sin(Beta)*2*p_1 + F*cos(Beta)*A_1-F*cos(Beta)*A_1+F*sin(Beta)*2p_2 So something clearly goes wrong here since I just end up with p1 = p2? Can anyone help me in the right direction?