Nondestructive Evaluation of the I-40 Bridge over the Rio Grande River

A nondestructive strength evaluation of the I-40 bridge over the Rio Grande River in Albuquerque, New Mexico (United States) was completed for the New Mexico Department of Transportation (NMDOT). The I-40 bridge is a precast, prestressed concrete girder bridge located within 3 miles of the "Big I" interchange carrying Interstates I-40 and I-25. Because of it's location, the I-40 bridge is subjected to large amounts of heavy truck traffic. The primary objective of the study reported in this article was to determine a more accurate capacity rating for the I-40 bridge and thus, reduce the number of overweight vehicle permit denials. To achieve this objective, a conventional rating analysis is first performed based on American Association of State Highway and Transportation Officials (AASHTO) guidelines. A diagnostic load test and a finite-element analysis are then completed. Details of the AASHTO rating analysis as well as the approach by which measured girder strains from the load test and finite-element results were considered in the capacity rating of the I-40 bridge are discussed. Findings from the study confirmed that the capacity ratings of the I-40 bridge could be safely increased by a factor of 1.7.