Analisi di travi colonne a sezione mista con connessione deformabile soggette a carichi di lunga durata

Composite steel-concrete beam columns are gaining importance in the last years due to their better static and dynamic behaviour when subjected to sustained loads respect to homogeneous beam columns. Beam columns are typically designed for middle span bridges, with deck length between 120 and 200 m. Today it is possible to find some other types of application for composite steel-concrete beam columns: they are used as natural substation to ties in bulkheads, when the depth of the excavation is high. An example of this innovative usage, is certainly the excavations for the new Madrid Underground. The goal of this Thesis, is to generalized the rotational function determined by Timoshenko, for a non homogeneous cross section, with partial interaction between steel and concrete, both in elastic and viscous-elastic field. In this work, the Authors have analysed the behaviour of a composite steel-concrete beam column, subjected to different static load cases and to temperature effect in the concrete part of the section. The behaviour of the beam column is first analysed under the hypothesis of small displacement, without any axial load P. The equilibrium equation and the congruence equation are written, from which the solution of the problem and the rotational function are derived. Then the problem is generalized considering the 2nd Order effects. Once the problem is determined in the elastic field, the Authors have generalized the solutions in the linear viscous-elastic field, using the Algebraic Method derived by Trost and the Fundamental Theorem derived by Professor Mola.