| Description |
Bridge design is moving towards performance-based design in which acceptable levels of damage following an earthquake are prescribed, allowing the possibility to repair and not replace bridges. A repair technique for precast reinforced concrete bridge column-to-footing assemblies constructed with Grouted Splice Sleeve (GSS) connections has been developed. The repair is implemented and verified through laboratory testing and Strut-and-Tie Models (STM). The repair utilizes prefabricated carbon fiber-reinforced polymer shells and epoxy anchored headed mild steel rebar to relocate the column plastic hinge. Prior to the repair procedure, two undamaged, as-built, column-to-footing specimens constructed with GSS connections were tested to failure under a quasi-static cyclic lateral load. During testing, both of the as-built specimens experienced longitudinal rebar fracture, with lateral load carrying capacities degrading to 63%-65% of their ultimate load capacities. The as-built column plastic hinge region was subsequently repaired by increasing the column cross-section from a 21 in. octagonal section to a 30 in. diameter circular section, over a column height of 18 in. The repaired specimens were tested following the same cyclic loading protocol as the as-built specimens. The plastic hinge was successfully relocated to the column section above the repair, and the failure mode was longitudinal rebar fracture in the relocated plastic hinge region. The repaired assemblies had an increase in the ultimate lateral load capacities of 28%-30%, while being capable of maintaining the as-built lateral displacement capacity. To aid in the design of future as-built and repaired assemblies, a conventional STM and a nonlinear STM were developed. Generic modeling parameters were developed, which can be used with varying reinforcement layouts and element geometries. Results from the STM models match the as-built and repaired test results, predicting the ultimate lateral load capacities and nonlinear force-displacement response envelopes. |
