The Research Administration at the Michigan Department of Transportation (MDOT) recently published a document with the agency’s latest research concerning post-tensioning cables and pre-stressing strands within concrete structures.
This research report is available online at the MDOT website. There is also a complete collection of all of MDOT’s Research Reports, from 1940 to 2015, on the website. They are linked using PDF files.
The goal of the study was to determine the various methods that can be used to find and analyze defects that are commonly found in steel-reinforcement corrosion. The researchers also looked at grout defects within post-tensioning applications.
The study evaluated side-by-side box-beam bridges for signs of damaged pre-stressing strands, as well as web reinforcement. The researchers also looked at decommissioned box beams within laboratory settings. This allowed them to analyze the residual flexural capacity and the deterioration of connections.
Other laboratory studies involved simulations depicting the loss of a cross-section area of steel reinforcement, debonding and voiding around steel reinforcement, and a variety of grouting issues.
The study results showed that the Magnetic Flux Leakage mobile scanner can find alterations within steel reinforcements. There was a strong correlation between steel reinforcements and beam flexural capacity, as well as the measured capacity of all of the involved scale box beams.
The full research report can be found at: www.michigan.gov/mdot/0,4616,7-151-9622_11045_24249_24251-371392–,00.html
