The present work has the aim of developing a formulation and a computational system, which should be used by the structural engineers an auxiliary tool in the definition of strut and tie models of bidimensional structures. In the developed system the user can define initially a very complex system with a great number of bars and many different directions. This initial solution can be based on both the stress results of a linear elastic finite element analysis and the experience of the engineer. As the user may be in doubt about the best model to be used he may superimpose in the initial model all the allowable solutions he may find. The aim of the system is to choose among all the allowable solution (these ones wich satisfy equilibrium and strenght) the more economical one. As more economical solution is considered the one which correspond to the least consumption of reinforcement. The problem formulation leads to a linear programming problem (LP) and the LINDO program [2] is used for solving it. The visualization of the model and results is also part of the system. It is based on the data generated by the LINDO program. The work is basicaly divided in three parts. In the first one a revision about strut and tie models as well as the basic knowledge in linear programming is presented. In the second part the problem formulation is shown and the last the results of the program are compared with those old the technical literature. The computational tool presented here may be of great utility in the definition of strut and tie models, but it has not by far the intention and the feeling of the engineers which shall ever prevail, inclusive in the critic analysis of the program results.