A methodology for circumferentially winding a graphite fiber-epoxy resin composite material around reinforced concrete columns for the purpose of the seismic-design retrofit of existing structures has gained approval for a major program of bridge retrofitting in California. A computational model employing three-dimensional finite element techniques is developed for the purpose of simulating the response of such retrofitted columns to seismic excitation. In the formulation of the computational model, the filament-wound composite material is modeled as a linear orthotropic membrane prestressed in the hoop direction, while the concrete is modeled as a continuum governed by three-dimensional nonlinear constitutive laws. The steel reinforcement is modeled using bear elements with one-dimensional kinematic-hardening plasticity laws, with the interface between the steel reinforcement and the concrete modeled using elements which permit frictional slip and gapping. The performance of non-retrofitted and of retrofitted columns is predicted, and comparisons with the full-scale test results are made.
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