Research on Composite Pile Behavior and Development of a Rock Strength DatabaseStatus: CompleteReport Date: 06/28/2018 Summary: For a bridge project in northern Minnesota, bridge designers needed data on hard rock that was too strong for MnDOT's standard testing approach. Researchers used a high-capacity load frame at the University of Minnesota to test rock samples from the project site and to examine the stiffness characteristics of concrete-filled steel piles used throughout the state. The study provided key data for the bridge design and validated MnDOT's practice of using concrete-filled steel piling for bridge load bearing and load transfer to the underlying bedrock. Final Deliverables: Report #2018-19 Report #2018-20 Research Summary Related Materials: Related Research: