Identification of Strut-and-Tie mechanisms in reinforced concrete structures using the cell method and genetic optimization techniques

The design of reinforced concrete elements by means of Strut-and-Tie (S&T) modelling is based on the identification of discrete truss resistant mechanisms within the overall structure, preliminary to the strength, deformability and/or ductility verifications. For complex structural concrete elements this phase can be somewhat simplified, and, most of all, made less dependent on the intuition and on the past experience of the designer, by adopting appropriate automatic techniques. The technique presented in the paper performs the search for the ideal S&T mechanism by means of a combined use of an elastic solver and an optimization algorithm. Namely, the proposed technique is a combination of the discrete continuum analysis method called Cell Method, which is applied to the elastic analysis of the considered structure, and of genetic optimization techniques, which are used to search for the solution. After a brief presentation of the implemented identification algorithm, and after the description of the adopted numerical method, some example structures are analyzed, and their resisting mechanisms to the applied loads are highlighted and commented. It is concluded that the proposed method is suitable for the search and identification of S&T mechanisms within reinforced concrete structures and elements, provided that adequate computing resources are available.