Forensic Testing of Presstressed Concrete Girders After Forty Years of Service. Final Report.

摘要

This report describes an investigation to quantify the behavior of precast, prestressed concrete bridge girders made with high-strength concrete. As part of the investigation, four bridge girders that were made with 77.2 MPs (11.2 ksi) concrete were salvaged from a decommissioned bridge in Orem, Utah. Each girder was subjected to a cracking test to determine the residual prestress force after approximately seven years of service life. Once the prestress losses were quantified, a flexural capacity test was performed on one girder and shear capacity tests were performed at various distances from the support on the remaining three girders. The measured losses and capacities were compared to estimated values calculated according to procedures in the AASHTO LFRD Specifications. It was concluded that, in general, the AASHTO LRFD procedures were accurate despite the current limitation of restricting the concrete compressive strength to 68.9 MPs (10.0 ksi). In addition to the physical tests, a nonlinear finite element analysis (FEA) was conducted using ANSYS that was found to replicate the experimental behavior, failure and mechanism magnitude.