A b s t r a c tBasic geometrical properties of optimal plane truss layouts for multiple displacement constraints and several load conditions are derived. These include the feature that at any point, optimal bars may run in at most two directions and that even for two nonsymmetric alternative loads at the same point the optimal two-bar layout is always symmetrical for a vertical support. The above general findings are illustrated with examples, in which the results are derived by several independent methods, including a proof of global optimality of the layout.