Practical plastic layout optimization of trusses incorporating stability considerations

Frequently the topologies generated using conventional discrete structural layout optimization methods may be shown to be in unstable equilibrium with the specified applied loading. Previously proposed methods to overcome this problem have tended to suffer from either a lack of rigour in identifying unstable solutions, a failure to properly consider all means of ensuring the stability of a framework, or are likely to be very computationally expensive. This paper discusses the drawbacks of current methods and introduces a conceptually simple approach that incorporates nominal lateral force load cases in a plastic linear programming problem formulation. Examples of stable solutions identified by this approach are discussed along with future developments to increase the practicality and efficiency of the method.