Civil Engineering

 

Date of this Version

5-2016

Citation

Stauffer, Steven T., "Performance Assessment of Deteriorated and Retrofitted Steel HP Piles" (2016). Civil Engineering Thesis, Dissertations, and Student Research.

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Civil Engineering, Under the Supervision of Professor Joshua Steelman. Lincoln, Nebraska: May, 2016

Copyright © 2016 Steven Stauffer

Abstract

Deterioration of aging bridges can be attributed to an assortment of mechanisms throughout the structure, with remediation policies also varying. This study focused on assessing the validity of the Nebraska Department of Roads’ (NDOR) reinforced concrete encasement retrofit for corroded steel HP piles. Experiments were designed and conducted to test the capacity of the NDOR retrofit and evaluate failure limit states. Two pile locations were considered: abutment and pile bent. For each location there was a non-deteriorated, deteriorated, and retrofitted case. These cases represented the pile at key stages during its life. NDOR’s concrete encasement retrofit provided the required stability and composite action to return the pile to full capacity. The key finding of the experimental study was a greater than anticipated steel-concrete bond stress. The bond stress observed was three times greater than the nominal recommended by AISC. A computational study was also conducted to investigate sensitivities and alternative configurations, such as geometric alterations, material properties, and reinforcement. The computational study emphasized the load transfer mechanism’s dependence on the type of load applied. Piles governed by axial compression with relatively minor moment were observed to be more sensitive to bond. The moment dominated loads required more surface to surface pressure transfer or bearing. Further investigation is recommended to determine the bond characteristics of steel fully encased by concrete.

Advisor: Joshua Steelman

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