Filament wound retrofitting of reinforced concrete bridge structures

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 used for the purpose of simulating the response of such retrofitted columns to seismic loading. The filament-wound composite material is modeled as a linear orthotropic membrane, and the concrete is modeled as a nonlinear 3D continuum governed by 3D constitutive laws which account for smeared cracking. Concrete inside the confined region is allowed a different constitutive relation to account for the different failure surface. The steel reinforcement is modeled using bar elements with one-dimensional kinematic-hardening plasticity laws. The performance of non-retrofitted and of retrofitted columns is compared. Finally, the computed internal stress distributions of circular and rectangular sections of nominally the same flexural capacity are compared.