Extension of displacement-based assessment to infilled RC frames

The purpose of this research was to assess the seismic response 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 and the residual strength with available experimental results. 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. On the basis of the results of these analyses, a displacement-based method for the assessment of infilled frames was proposed. The effectiveness of this method was verified through comparison between the displacement demand estimated with the proposed procedure and that obtained from nonlinear dynamic analyses.