ASCE/SEI 41 Provisions on Deformation Capacity of Older-Type Reinforced Concrete Columns with Plain Bars

This study contributes to the improvement of capacity models for older-type RC members to be used in the seismic assessment of existing RC structures. A database of experimental tests on RC columns with plain bars is presented. Due to the low bond strength, the deformation capacity of these members is particularly influenced by fixed-end rotation mechanism compared with members with deformed bars. ASCE/SEI 41 provisions on the deformation capacity of older-type RC columns, including later proposed modifications, are reviewed. Provisions for the evaluation of effective stiffness are reviewed, too, and special attention is paid to failure mode classification. The effectiveness of such provisions for columns with plain bars is evaluated through their application to the presented database. Results obtained from the application of the effective stiffness model are illustrated, and possible improvements are discussed. A significant conservatism in the plastic deformation capacity model is observed. Deformation limits could be relaxed while still meeting code safety requirements. The amount of this adjustment for ASCE/SEI 41 provisions on the deformation capacity of older-type RC columns is evaluated.