1. The problem statement, all variables and given/known data A jack-stand with three equally spaced legs (120 degrees) are connected to a center tube is loaded axially with 36,000 pounds. Each leg has a horizontal cross member 11 inches from the ground. All connections are welded. Set up FBD and find reaction forces. 2. Relevant equations ∑Fy = 0 ∑Fx = 0 ∑M_x = 0 3. The attempt at a solution I guess I'm confused about the connections being rigid and welded. Most structures I have seen in examples are assumed to be pinned and therefore do not transmit moment/shear loads. Solving globally for ∑Fy = 0 36,000 = 3*Na = 0 Na = 12,000 (Vertical reaction at each foot contacting ground) The horizontal reaction at each foot is the opposition of friction: Fa = μsNa Fa = (0.5*12000) = 6000 (I use a μs = 0.5 for concrete/steel) Summing moments about A: ∑Ma = (15*R_dy) + (15*R_cy) - (28*R_cx) = 0 ∑Fy = Na - R_dy - R_cy = 0 ∑Fx = R_cx - Fa = 0 R_cx = 6000 Plugging everything in I get R_dy = 0?? So DB is a zero force member then if CB is in compression? I would think the 36,000 would transform some load to the member DB. The other thing I'm confused about is there a reaction at point B between the angled leg and the cross-member? I don't know if each of these points would have a bending moment associated with it either since they are rigid and not pinned.