On the Evaluation of the Nonlinear Seismic Response of Infilled RC Frames

The purpose of this research was to assess the seismic esponse of RC infilled frames. In order to evaluate the behaviour of these structures, it was fundamental to define an appropriate analytical model. Several models were proposed in literature for the masonry infills. In this study the equivalent strut model for monotonic loading proposed by Al-Chaar was considered. This model was extended to the case of cyclic loading by calibrating the degradation of strength and stiffness, the residual strength and the loading and unloading branches. The model was then applied for investigating the seismic response of infilled RC frames: pushover and nonlinear dynamic analyses were carried out for obtaining the response in terms of base shear-top displacement and for estimating the configuration of collapse. Furthermore a displacement-based method for the assessment of infilled frames was proposed. In order to prove the validity of the proposed method the displacement demand calculated with the assessment procedure was compared with the displacement obtained from nonlinear dynamic analyses.