Analytical Models for Seismic Repair of Bridge Columns Using Plastic Hinge Relocation

This paper presents two analytical models, Model Fiber and Model RS, which predict the seismic performance of two repaired specimens using a carbon fiber-reinforced polymer (CFRP) shell and epoxy anchored headed steel bars to relocate the column plastic hinge. In Model Fiber, distributed plasticity considering bond slip is assumed to be concentrated in a plastic hinge length of the nonlinear beam-column element instead of the whole length of the element; this was implemented using the BeamWithHinges element in OpenSees. In Model RS, concentrated plasticity was considered using a non-linear moment rotational spring located at the repaired cross-section. A sectional moment-curvature analysis is performed, based on damaged steel properties and considering bond slip, to obtain the moment-rotation relationship, which is assigned to the non-linear rotational spring. Both analytical models proposed in this paper include low-cycle fatigue of longitudinal steel bars and bond-slip effects. Numerical simulations show that the analytical results, in terms of hysteretic response, cumulative hysteretic energy, and bending moment-rotation, agree with the experimental results.