Ultra-high performance concrete (UHPC) is a new class of concrete materials that features high strength, ductility, and damage tolerance. This study experimentally evaluated three new UHPC jacketing strategies for retrofitting shear-deficient reinforced concrete (RC) columns, including cast-in-place UHPC jackets with or without steel bar mesh and prefabricated UHPC panels with steel bar mesh. The steel mesh had a high nominal yielding strength of 550 MPa. The impact of different axial load levels on the seismic performance of the retrofitted columns was also explored. Two control columns and five retrofitted columns were tested under lateral displacement reversals. Results showed that while all retrofitting methods enhanced the strength capacity of the shear-deficient column, the UHPC jacketing without steel mesh failed to improve the shear-critical behavior and drift capacity of the column. With the inclusion of high-strength steel mesh in the UHPC jacket, the control columns’ brittle shear failure was significantly improved. The proposed novel UHPC jacketing method with on-site installation of prefabricated UHPC panels showed comparable seismic retrofitting performance to the cast-in-place UHPC jacketing. In addition to the experimental study, suitable strength models, which can reasonably evaluate the strength and failure mode of the RC columns retrofitted using the proposed UHPC jackets, were suggested.

超高性能混凝土（UHPC）是一类具有高强度、高延展性和抗损伤能力的新型混凝土材料。本研究通过实验评估了三种用于改造抗剪钢筋混凝土 (RC) 柱的新 UHPC 护套策略，包括带有或不带有钢筋网的现浇 UHPC 护套和带有钢筋网的预制 UHPC 面板。钢网具有550 MPa的高公称屈服强度。还探讨了不同轴向荷载水平对改造柱抗震性能的影响。两个控制柱和五个改装柱在横向位移反转下进行了测试。结果表明，虽然所有的改造方法都提高了抗剪力不足柱的强度能力，没有钢网的 UHPC 护套未能改善柱的剪切临界行为和漂移能力。通过在 UHPC 护套中加入高强度钢网，控制柱的脆性剪切破坏得到显着改善。拟议的新型 UHPC 护套方法与现场安装预制 UHPC 面板显示出与现浇 UHPC 护套相当的抗震改造性能。除了实验研究外，还建议了合适的强度模型，该模型可以合理地评估使用提议的 UHPC 导管架改造的 RC 柱的强度和破坏模式。拟议的新型 UHPC 护套方法与现场安装预制 UHPC 面板显示出与现浇 UHPC 护套相当的抗震改造性能。除了实验研究外，还建议了合适的强度模型，该模型可以合理地评估使用提议的 UHPC 导管架改造的 RC 柱的强度和破坏模式。拟议的新型 UHPC 护套方法与现场安装预制 UHPC 面板显示出与现浇 UHPC 护套相当的抗震改造性能。除了实验研究外，还建议了合适的强度模型，该模型可以合理地评估使用提议的 UHPC 导管架改造的 RC 柱的强度和破坏模式。