A COMPARATIVE STUDY ON THE ACCURACY AND EFFICIENCY OF TWO BIAXIAL HYSTERETIC MODELS SUITABLE FOR ELASTOMERIC BEARINGS

In common practice, uncoupled hysteretic models, that is, models that do not consider the bi-axial interaction between the restoring forces along two generic orthogonal transverse directions, are typically employed to perform nonlinear time history analyses of base isolated structures. However, such models do not suitably reproduce the exact response of the structure when the system is subjected to external excitation in two orthogonal directions. Thus, the selection of suitable phenomenological model and the time integration method is important while carrying out nonlinear time history analysis (NLTHA) of base isolated structures. In the present study, a detailed investigation is carried out to assess the effectiveness of two hysteretic models to reproduce the hysteretic behaviour of the elastomeric bearings. A three-dimensional base-isolated reinforced concrete building is analysed under earthquake excitations, by employing a novel biaxial phenomenological model denominated Multiple Springs Exponential Model (MSEM) and Biaxial Bouc-Wen model (BBWM). Numerical accuracy and the computational efficiency of these methods are assessed through NLTHA. The results show that the novel method is advantageous and computationally efficient in comparison with BBWM.