Al Ghorbanpoor
University of Wisconsin-Milwaukee (UWM)

Friday February 3, 2012
Room 1047 ERF

Corrosion and its Detection in Tendons of Segmental Concrete Bridges

This presentation will focus on the use of a newly developed NDE system, the magnetic flux leakage (MFL) system, to detect corrosion in post-tensioned (P-T) tendons of segmental concrete bridges. Segmental concrete bridge structures primarily rely on P-T tendons to carry their relevant loads. During recent years, many bridge owners have experienced deterioration, and sometimes complete fracture, of prestressing steel within P-T tendons due to corrosion. Since prestressing steel within P-T tendons is normally hidden from view, routine inspection practices do not allow for detection of corrosion in such tendons.

A magnetic flux leakage (MFL) system, developed recently at UWM, has been shown to be effective in detecting corrosion in external tendons of segmental bridges. The system consists of a set of strong permanent magnets, a series of Hall-effect sensors, and a number of electronic and mechanical devices. The system has been evaluated and optimized for field applications through conducting extensive laboratory and field tests. It has been demonstrated that the current MFL system is capable of detecting corrosion, or section loss, as small as less than 1 percent of the cross sectional area of external P-T tendons of segmental bridges. The MFL system has been used on a number of major cable supported bridges in the USA and abroad. This presentation will include a discussion of the corrosion problems in P-T tendons of segmental bridges as well as case studies for application of the MFL system to assess the condition of external tendons in major post-tensioned segmental concrete bridges in the US.

Biographical Sketch

Al Ghorbanpoor is currently a Professor of Structural Engineering and Associate Dean for Research in the College of Engineering at the University of Wisconsin-Milwaukee where he has been employed since 1986. His research focus is on the development and application of NDE systems to bridge structures, fatigue and fracture, rehabilitation of bridge structures, and performance evaluation of coating systems for highway applications. He is a Fellow of ASCE and registered Professional Engineer.