The American Council of Engineering Companies of Minnesota (ACEC/MN) has named the TH 63 Bridge over Mississippi River H-Pile Downdrag Monitoring project the winner of a 2021 Grand Award for Engineering Excellence.
The ACEC is a federation of 52 state and regional councils dedicated to government advocacy, political action, and business education on behalf of member firms. ACEC/MN’s annual awards program recognizes engineering achievements that “exhibit the highest degree of merit and ingenuity.” Entries are judged by an objective panel based on originality and innovation; future value to the engineering profession; social, economic and sustainable design considerations; complexity; and success in meeting the client’s needs.
Liang Chern Chow, P.E. and Derek Van Heuveln, P.E. of American Engineering Testing (AET) served as project leads for this unique pile monitoring project, results of which were also presented in May at IFCEE 2021 by Federal Highway Administration (FHWA) engineer Derrick Dasenbrock, P.E., D.GE.
When MnDOT engineers slated the 57-year-old Eisenhower Bridge near Red Wing, Minnesota for replacement, they noted severe settlement issues on the northern side. Because excessive settlement can overstress deep foundations, MnDOT decided to monitor loads on the new bridge’s steel H-pile foundation.
AET and Zenith Tech (ZTI) collaborated during construction to install strain gauges on four piles driven 150 feet below the new bridge abutment and electronically monitored them for three years. Data from these sensors let MnDOT check measured pile loads against design assumptions — to ensure the safety and performance of the new foundation.
AET, MnDOT, and FHWA engineers also gleaned insights on the phenomenon of downdrag and how drag load forces develop over time, with the expectation that it will improve the design of future bridges built on “soft” riverside soils, leading to savings in both time and materials.