Viscoelastic Heterogeneous Structures With Variable Structural System

Viscoelastic structures that undergo an evolution of the structural system, which passes from an initial to a final configuration, with an increase at different times of the number of the redundant reactions, are analyzed. These actions, which restore the compatibility conditions at the delayed restraints, are time-dependent. Moreover, they depend on the rheological properties of the material, which are, in general, different for each single part (heterogeneous structures). Under these circumstances, the general statement of the problem is presented. The mathematical formulation has demonstrated that the problem is governed by a coupled system of Volterra integral equations for each building stage, which, in general, may be solved only by a numerical procedure, with an overlarge number of calculations. A number of particular cases are also discussed. Subsequently, in order to investigate the influence of each single cause of heterogeneity a parametric analysis was performed by applying the numerical step-by-step procedure of the general method to an opportune simple structural model.