Rectangular C-Device with Circular Transitions: Modelling Approaches and Development of an Equivalent Nonlinear Inelastic Spring for Seismic Analysis

Yield devices of “C” shape, known as C-devices, supplement the energy dissipation sources when installed in earthquake resistant structures. However, the explicit modelling of C-devices is time consuming. Accordingly, this paper presents a new reliable methodology to define and calibrate an equivalent uniaxial inelastic spring that effectively reproduces the expected hysteretic response of a C-device. The shape of the C-device under study resembles that of a rectangular portal frame with circular interior corner transitions to avoid stress concentration and to control the extension of the dissipative region. The characterization of the properties of the equivalent spring is supported by both, finite element (FE) analyses of a family of C-devices and by experimental validation. Two types of FE models are used to predict the response of the C-device. A simple FE model idealizes the device as an inelastic frame with pinned supports, whereas the more elaborate model analyses the device as a C-shaped inelastic plate under in-plane actions and explicitly reproduces the boundary conditions of the plate at the device connections. Results indicate that the FE analysis results and those obtained with the equivalent inelastic spring are in a good agreement with experimental tests for monotonic and reversed cyclic loading