Pantazopoulou, StavroulaSalazar Gonzalez, Roberto2025-04-102025-04-102025-01-062025-04-10https://hdl.handle.net/10315/42871Ultra-high performance fiber-reinforced concrete (UHPFRC) has emerged in the last decade as a new alternative material for retrofitting reinforced concrete structures such as buildings and bridges. One of the most common applications of UHPFRC today is restoring bridge decks and construction joints. UHPFRC can also be applied to the retrofit of principal structural components, such as beams and columns. Decks are repaired by the addition of UHPFRC overlays, whereas columns can be retrofitted with UHPFRC by applying a new layer on the original cross-section, or by removing the concrete cover and replacing it with UHPFRC. This technique is known as jacketing, and it is an attractive solution due to the outstanding mechanical properties of UHPFRC and the fact that the retrofit may be limited to the length of the critical regions and does not have to cover the total height of the column. Specifically, with regards to UHPFRC Jacketing, research on UHPFRC has been conducted when used as a cast-in-place solution. In this research, UHPFRC jacketing is studied as a seismic retrofit alternative, to quantify the jacket's contribution to the various mechanisms of resistance (flexure, shear, reinforcement anchorage capacity, and the confinement effectiveness of the jacket in enhancing the strength and deformation capacity of encased concrete). With confinement effectiveness being the primary knowledge gap, the study included an extensive experimental component, where rectangular concrete prisms modeling concrete columns were jacketed with precast UHPFRC jackets. The objective of the experimental study was to test the proof of concept of jacketing with precast jackets made of UHPFRC, and to also shed light on the contribution of the jackets to the deformation capacity of encased concrete in order to quantify the jacket's effectiveness. As part of the research, the method of connection of the jacket segments and characterization of the materials were designed and optimized through testing. Two possible connectors were designed and tested, providing good results. Several columns were tested under monotonic and cyclic loading, after assembling the precast jackets designed and fabricated for the needs of the study. Parameters of investigation included two jacket thicknesses (i.e. 25 mm and 37.5 mm), the type of connectors between precast components, the loading method (monotonic or cyclic compression load on the encased concrete) and the method of jacketing (cast in situ vs. attaching precast jackets). Finite element modeling was included to understand the lateral resistance to dilation of the encased concrete imparted by the jackets. The deformation capacity of the columns was enhanced substantially. The findings in this research aim to provide a valuable understanding of UHPFRC as a retrofit solution in the form of jacketing.Author owns copyright, except where explicitly noted. Please contact the author directly with licensing requests.Electronic Thesis or Dissertation2025-04-10UHPCUHPFRCSeismicRetrofitConcrete piersJacketingPrecast