Repair of damaged precast RC bridge columns with grouted splice sleeve connections using CFRP shells and plastic hinge relocation

Abstract

A repair technique for damaged precast reinforced concrete (RC) bridge columns with grouted splice sleeve (GSS) connections has been developed that utilizes prefabricated carbon fiberreinforced polymer (CFRP) shells and epoxy anchored headed mild steel bars to relocate the column plastic hinge. Undamaged columns with two different GSS systems were tested to failure using cyclic quasi-static loads. One GSS system was used to connect an RC bridge pier cap to a column. The second GSS system was used to connect an RC footing to a column. Failure of the two original specimens occurred at drift ratios between 6% and 7% with longitudinal bars fracturing in the column plastic hinge region. The column plastic hinge region was then repaired by increasing the column cross section from a 21 in. octagonal section to a 30 in. diameter circular section with an 18 in. length. The repair was constructed using prefabricated CFRP shells. Headed mild steel bars were epoxy anchored into the pier cap and footing inside the CFRP shells. Nonshrink concrete was used to fill the void between the original columns and CFRP shells. Compared to the undamaged assemblies, the repaired specimens failed at the same drift ratios and greater ultimate load values. The plastic hinge was successfully relocated to the original column section adjacent to the repair and the failure mode was bar fracture in the relocated plastic hinge region. The method is a viable technique for seismic repair or seismic retrofit of precast GSS assemblies in column to footing or column to pier cap connections.