Saving Our Infrastructures
“Leon” Lung-Yang Lai, Ph.D., P.E., S.E., M. ASCE
Peter Kim, P.E., M. ASCE
Tony Jen, P.E., M. ASCE
Specialty Engineering, Inc.
422 Mill Street
Bristol, PA 19007
Keywords: Prestressed Concrete, Inspection, NDT, Bridges
On March 17, 2008, two engineers of Specialty Engineering, Inc. (SEI) found a 6’ long vertical crack on a reinforced concrete column under a viaduct carrying I-95 in the City of Philadelphia, Pennsylvania. They immediately notified Pennsylvania Department of Transportation (PennDOT), following the emergency reporting procedure. Within a couple hours, PennDOT engineers rushed to the site and decided to close I-95 Southbound for emergency repair. A segment of I-95 Southbound was shot down for three days and about 1 million motorists were affected. Other similar structures adjacent to that column were also fully inspected to ensure that no similar defects exist before I-95 was reopened to traffic. This paper presents the causes, reporting procedure, and rehabilitation of this critical defect on the most important corridor in the Philadelphia area.
A fascia beam of a “non-composite” prestressed concrete adjacent box beam bridge in Washington County in Pennsylvania collapsed in December of 2005. Because of this incident, PennDOT has revised the NBIS inspection and rating requirement and procedures, and has put high alert on this type of bridges. Many of these bridges exhibit apparent deteriorations, such as longitudinal cracks on bottom flanges and differential camber between beams. Many of them have exposed and broken prestressed strands. PennDOT recently awarded Lehigh University and SEI a research contract to identify NDT technologies for determining the (corrosion) condition of the strands in prestressed concrete box beam bridges. This paper will also present the recent inspection findings of some of this type of structures, the impact of observed defects on the bridge load carrying capacity, and will also discuss the progress of the PennDOT research project.
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