Development and Experimental Testing of Ultrahigh-Performance Concrete Pile Foundation Elements

Many aging bridges in the United States, built in the 1960s with a 50-year design lifespan, are deteriorating. Recent research seeks to improve construction materials and methods in order to extend bridge lifespans, reduce repair requirements, and retrofit structurally deficient elements. Driven pile foundations are critical to a structure's long-term stability and safety but can be damaged during installation or deteriorate over time due to harsh environmental conditions. Repairing or replacing these systems can be difficult and expensive.Ultra-High-Performance Concrete (UHPC) is an advanced cementitious material with superior mechanical and durability properties when compared to standard concrete. The problems associated with driven pile foundations can be alleviated by designing a pile foundation system using UHPC. This study aims to create a viable UHPC foundation system as an alternative to traditional steel and concrete driven piles.As an alternative to conventional HP steel piles, two H-shaped 12-in. and 14-in. deep UHPC pile sections and a 16-in. H-shaped section as an alternative to 16-in. square prestressed pile were designed. Full-scale piles were cast and tested under various flexural and shear loading conditions. The results show that these piles are viable alternatives to the standard piles that are currently used, and that current first principles methods adequately capture their behavior.To ensure that these piles can be used as field applications as part of a bridge structural system, two other aspects of foundation elements were investigated: interface shear behavior and splice design. The shear behavior along UHPC-UHPC interfaces is crucial for ensuring that UHPC piles embedded in UHPC pile caps or abutments will perform adequately. Over 100 small-scale specimens with varying low-amplitude texture morphologies were constructed and evaluated for this purpose. It was determined that current code specifications should account for texture spacing.A construction-friendly splice design similar to the current standard practice for steel HP piles was developed for field implementation of UHPC piles. Full-scale splice design, construction, and testing under flexure, shear, and tension conditions. According to the findings, the splice can provide at least 60% of the strong-axis flexural capacity. To achieve full moment capacity, the splice must be lengthened.