Computer analysis of slackened systems under variable loads

The paper deals with a particular class of slackened-elastic-plastic skeletal structures where one-parameter contact and yield conditions are introduced. The mathematical model of this problem represents a discrete form of Kuhn-Tuckerʹs conditions, and is equivalent to dual quadratic programming problems (QPPs). The uniqueness of the solution to this problem is guaranteed, with exception of some particular cases where the structure converts into a mechanism, and the solution corresponds to dual linear programming problems (LPPs). The authors propose another approach to solving the problem. The uniqueness of the solutions allows a pure elastic analysis procedure, which satisfies some additional constraints imposed on the objective function, to be used. The numerical solution is obtained by means of an iterative procedure using the trial-and-error method where the physical (energetic) meaning of the problem is utilized.