A new and unified model for prediction of ultimate deformation of linear concrete members with and without jacketing

Existing prediction models for peak load of reinforced concrete columns with jacketing are mostly empirical and are different for different jacketing materials. For rational seismic design, ultimate deformation is a better limit state than peak load, however there are only few prediction models available. This study presents a new and unified analytical method with potential shear strength concept and consideration of flexure-shear interaction, which is applicable to both cases with and without jacketing. The method can be applied to various jacketing materials; reinforced concrete, steel plate and FRP sheet including conventional FRP and large rupturing strain (LRS) FRP. The model consists of flexure strength/stiffness model and shear strength/stiffness model. The flexure model interacts with the shear model through the reduced neutral axis depth and the increased tensile force in tension reinforcement by tension shift in shear cracking zone. On the other hand the shear model interacts with the flexure model through the yielding of tension reinforcement and the concrete strength degradation in compression softening. The method can predict the load-deformation relationship including postpeak region and better ultimate deformation with LRS FRP sheet in the experiments of this and previous studies.