Forensic Testing of Post Tensioned Concrete Girders

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CAIT project no.: CAIT-UTC-033

Fiscal Year: 2013/2014

Status: Final

Rutgers-CAIT Author(s): Paul Barr, Ph.D., Utah State University, Patrick Szary, Ph.D

Sponsor(s): Utah Department of Transportation, FHWA - RITA


All across the United States, various state departments of transportation are faced with the problem of an aging infrastructure and insufficient resources to meet the needs.  As a result, many bridges are being subjected service lifes that are longer than originally anticipated when originally designed.  Understanding the behavior of this aging infrastructure is essential to making judicious decisions with the limited resources.  With the reconstruction of the I-15 Interstate near Provo, Utah many bridge replacements were required.  As part of a previous UTC project, four high strength, self consolidated prestressed concrete girders were obtained an tested to determine residual prestress force, flexural capacity and shear capacity.  During the procurement of these girders researchers discovered and obtained a group of post tensioned concrete girders that are over 40 years old.  These girders were post tensioned using three curved bars.  The girders have a wider end block for the post tensioning anchorage.  These girders are unique in many ways and presented a rare opportunity to evaluate the long term behavior of post-tension bridge girders.  There girders were tested along with the prestressed girders but the analysis has not been performed.  There is very little research that has been done on this type of girder and the results will be valuable for state and federal agencies as well as other researchers.  This research is to analyze and compare the measured results with current design procedures and nonlinear finite-element methodologies.