Concentrated and Distributed Plasticity Models for Seismic Repair of Damaged RC Bridge Columns

Two models, Model Fiber and Model Rotational Spring (RS), simulating the seismic performance of repaired column-to-cap beam/footing connections using a carbon fiber-reinforced polymer (CFRP) donut are presented in this paper. In Model Fiber, distributed plasticity was assumed over a plastic hinge length of the nonlinear beam-column element. In Model RS, concentrated plasticity was considered using a nonlinear moment rotational spring located at the repaired cross section. Previous concrete damage and low-cycle fatigue of longitudinal steel bars as well as bond-slip between the damaged steel bars and surrounding concrete were included in the proposed numerical models. Numerical simulations show that the results are in good agreement with the experiments in terms of structural response, cumulative hysteretic energy, and moment-rotation capacity. Model Fiber can also predict the local response and low-cycle fatigue of the longitudinal steel bars. Using appropriate pinching parameters, Model RS can model accurate pinching behavior for both the repaired cast-in-place (CIP) and precast concrete specimens.