Non-Destructive Estimate of the Rate of Change of Structural Degradation of the211 Lavic Road Overcrossing

摘要

The objective of this study is to quantitatively evaluate, using recent work in211u001enondestructive damage evaluation (NDE) and systems identification at Caltrans, 211u001ethe rate of possible structural stiffness deterioration of the Lavic Road 211u001eOvercrossing (Bridge No. 54-734). The structure is suspected of having being 211u001econstructed with reactive aggregates. To meet this objective, the following eight 211u001etasks were performed. First, a modal test was performed on the bridge in December 211u001e1997. Second, a modal analysis was performed on the test data and selected modal 211u001eparameters of the bridge were extracted. Third, a 3-dimensional finite element 211u001emodel of the superstructure and substructure of the bridge was developed. Fourth, 211u001eusing the finite element model and the frequency modal parameters extracted from 211u001ethe field data, baseline modal parameters for the bridge and mass and elastic 211u001eparameters of the deck, column, and abutments were generated. Fifth, using the 211u001efield modal parameters and the baseline modal parameters, potential damage in the 211u001estructure at the member level was localized. Sixth, using the field modal 211u001eparameters and a knowledge of the location of damage, a damage severity was 211u001eassigned to each of the identified members. Seventh, using the location and 211u001eseverity of the damage along with the baseline model, the detailed structural 211u001eproperties of the existing bridge were estimated. Finally, each of the previous 211u001eseven tasks were repeated nine months later (September 1998) and the magnitude of 211u001edeterioration of the structural members was quantified for the elapsed period of 211u001etime.