LAUSR

This paper proposes a simplified envelop curve model for evaluation of capacity curve of reinforced recycled aggregate concrete (RAC) columns subjected to seismic loads. A seismic research database containing 53 reinforced RAC columns was established and applied to calibrate the envelop curve model. The effective initial stiffness, feature drift ratio, and various loads of collected RAC columns were discussed and modelled by a database analysis and a simplified sectional analysis. According to comparative results, effective initial stiffness, yield stiffness, and various drift ratios of RAC columns could be modelled simply considering the effects of axial load ratio and replacement ratio of recycled aggregate in RACs. Considering the weak self-properties of recycled aggregates, the study suggested the yield load of reinforced RAC columns under seismic loads could be taken simply as 80% of calculated peak load of the columns. The ultimate drift ratios of RAC columns were evaluated by a simplified linear function of peak drift ratios. The paper found that the lateral confinement index of columns has a significant influence on the flexural envelop curves of reinforced RAC columns. The comparative results verified that the proposed envelop curve model can evaluate the experimental behaviour with a good agreement.