Iowa Department of Transportation
Iowa Highway Research Board
Sri Sritharansri@iastate.edu email >
Faculty Affiliate, BEC
About the research
With 21% structurally deficient and 6% functionally obsolete bridges, Iowa ranks among the bottom states in bridge infrastructure quality. Extending the service life of new and existing bridges through the development of new solutions has, therefore, been one of the principal challenges of the state. Given that 30% of the overall cost of bridges is directed toward the foundation and the difficult accessibility of foundation elements for maintenance, creative solutions are needed to lengthen the service life of bridge substructures.
The recent advancements in ultra-high-performance concrete (UHPC) offer great potential to overcome this challenge. The durability and high strength properties of UHPC offer a superior advantage over other types of material commonly used in bridge foundations. The use of UHPC for piles was investigated in a previous project, where a UHPC pile cross-section was designed and optimized. Through analytical and experimental investigations, the study demonstrated UHPC as a practical alternative for bridge piles.
To advance the UHPC pile design previously developed, this study aimed to develop connection details, improve drivability and installation, and conduct field performance verification. New splice details were developed, and their performance was evaluated in various laboratory and field tests. Additionally, the suitability of the Iowa Department of Transportation’s (DOT’s) current pile-to-abutment connection details for the UHPC pile was investigated in laboratory experiments. After completing a vertical and lateral load test in the field on two UHPC piles to optimize pile design and evaluate the performance of the splice, a UPHC production pile was implemented in an actual bridge abutment foundation, and its performance under the cyclic lateral movement of the bridge was monitored over two years.
The new splice design details performed adequately in both laboratory and field experiments, and they are recommended for implementation. The completed tests also demonstrated that current Iowa DOT pile-to-abutment connection details are adequate for utilizing UHPC piles in routine design. The field implementation and monitoring of the UHPC production pile indicated satisfactory performance and showed that UHPC piles can be used in place of the commonly used steel piles, thereby increasing durability of foundations in Iowa bridges.