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Performance Evaluation and Design Considerations for Reinforced Ultra-High Performance Concrete (UHPC) Bridge Decks and Connections
Reinforced concrete bridge decks are typically designed using empirical method or traditional method. Both design procedures require a thick mat of concrete reinforced with four layers of steel reinforcement. However, given the outstanding properties of Ultra-High Performance Concrete (UHPC) compared to Conventional Concrete (CC), lighter sections with minimal reinforcement can be used to achieve the required load-bearing capacity. Moreover, using UHPC for bridge decks can considerably improve the Accelerated Bridge Construction (ABC) method. This study presents an experimental investigation conducted on eight mild steel-reinforced and five prestressed double tee UHPC bridge decks subjected to cyclic, monotonic, and shear loading. Furthermore, twelve quick and economical deck-to-girder connection using UHPC material only, without inserts, were prepared and tested using double shear test and the interface shear strength determining the interface shear strength for UHPC with varying fiber contents and ages. Moreover, two deck-to-deck connections using UHPC and epoxy were suggested and evaluated under cyclic and monotonic loading.Additionally, an experimental program was carried out to study the shrinkage and early age creep properties of UHPC. Three different test methods were used to study three various shrinkage types namely: ASTM C1698 test for autogenous shrinkage, Total shrinkage (TS) test for total shrinkage, and a new test method called axially restrained shrinkage (ARS) was suggested for restrained shrinkage.Results indicated that both mildly reinforced and prestressed UHPC decks withstood much larger loads than required in design and outperformed expectations. Both options appear viable from fatigue, monotonic, and shear load perspectives. Moreover, UHPC with 2% fiber content had a nominal interface shear stress capacity of approximately 2.25 ksi. The cohesion factor for the UHPC containing 1.5% steel fiber can be calculated as follows: c = 0.39√f′UHPC . Additionally, both UHPC and epoxy deck-to-deck connection performed well under cyclic loading as no stiffness degradation or connection cracks were observed. Moreover, two procedures were proposed to determine the early age creep and restrained shrinkage based on mechanics. For the experimental results obtained in this study, an early creep coefficient of 1.2 to 1.4 can be used for steam-cured UHPC material, while a range of 1.9 to 2.1 is recommended for chamber-cured UHPC material. Regarding the total shrinkage (autogenous and dry) strain of 2% fiber UHPC, it is recommended to consider a total shrinkage of -650 microstrain for chamber-cured UHPC and -470 microstrain for steam-cured UHPC.
Engineering|Civil engineering|Materials science
Tahat, Mohammad Fandi, "Performance Evaluation and Design Considerations for Reinforced Ultra-High Performance Concrete (UHPC) Bridge Decks and Connections" (2023). ETD collection for University of Nebraska-Lincoln. AAI30691895.