Validation of a rheological model for HDR based devices by tests on a full scale steel-concrete composite frame

High Damping Rubber (HDR), commonly used for seismic isolation devices, may also be used to produce passive dissipation devices. HDR-based devices have a number of advantages: they are recentering, they can withstanding a large number of cycle and moreover they can dissipate energy even under low excitations, such in the case of frequent earthquakes or wind actions. This paper presents a validation of a nonlinear viscoelastic model for HDR-based dampers already proposed by the same authors, by means of comparisons with experimental tests carried out on a full scale steel-concrete composite mock-up. The paper firstly describes the real scale mock-up and its characterization, in the elastic displacement range, carried out by means of free vibration tests. HDR devices were introduced in the frame by means of chevron-type braces and dynamic free vibration tests, force-controlled tests and displacement-controlled tests were performed. The coupled system is modelled as a nonlinear SDOF system consisting of an linear elastic element placed in parallel with HDR dampers. All experimental tests were numerically simulated with satisfactory results.