Seismic Resilience Study of Piers Enhanced by Ultrahigh-Performance Concrete Jackets Based on Cyclic Loading Test and Static Push-Over Curves

Abstract

The efficiency of novel retrofitting of constructed reinforced concrete piers with ultra-high performance concrete (UHPC) jackets was investigated. Pier specimens were subjected to a series of cyclic quasi-static stress tests, whereby two tests employed UHPC jackets with a single width (UHPC-W), while the other two used UHPC jackets with several narrow widths (UHPC-N). The seismic responses were compared in terms of energy dissipation, ductility, hysteresis curves, and skeleton curves. The seismic capability of reinforced concrete piers is increased by both W-type and N-type UHPC jackets by reducing concrete damage. Reinforced concrete piers with a UHPC-W jacket offer greater lateral strength but are more vulnerable to plastic hinge movement. On the other hand, the UHPC-N jacket increases the ductility of concrete and conceals concrete damage. However, construction quality was critical to ensure tight contact between the multiple strips and the reinforced concrete shaft. Based on the implicit method, a 3D finite element model is recommended for nonlinear static elasticplastic analysis. The nonlinear reinforcement model, bond-slip behavior, and concrete damage plastic model are all included in the finite element model. In order to assess the seismic susceptibility of the retrofitted piers, various limit states were defined, and fragility curves unique to the particular structure were produced.