REDUCED ORDER MODELING FOR THE DYNAMIC ANALYSIS OF STRUCTURES WITH NONLINEAR INTERFACES

In the present paper, linear substructures with nonlinearities localized at their interfaces, such as the joints in a beam structure, are studied. By subdivision of the total structure into substructures, reduced subsystems are obtained by component mode synthesis. Nonlinear elements are introduced at supports or between substructures. A numerical example is presented where a beam subjected to blast loading is studied. The influence of the nonlinear behavior as well as the number of retained fixed-interface normal modes in the reduced subsystems are evaluated. The response is also compared to the response of equivalent single-degree-of-freedom systems, which are frequently employed in blast load design calculations. For the load cases studied, the displacement computed from an equivalent single-degree-of-freedom system correspond fairly well to the displacement given by a refined two-dimensional beam model, reduced by substructuring. In contrast, the shear force differs significantly due to that higher order modes are neglected in the single-degree-of-freedom system. (Less)