Dynamic Bridge Substructure Evaluation and Monitoring

FOREWORD This research project was performed to investigate the possibility that, by measuring the dynamic response characteristics of a bridge substructure, it might be possible to determine the condition and safety of the substructure and identify its foundation type (shallow or deep). Determining bridge foundation conditions with this approach may be applied to quantify losses in foundation stiffness caused by earthquakes, scour, and impact events. Identifying bridge foundation type may be used to estimate bridge stability and vulnerability under dead and live load ratings, particularly for unknown bridge foundations. Of several protocols evaluated, Hilbert-Huang Transforms (HHT) showed the most promise for structural damage diagnosis. Further work using the HHT method is recommended. The results of this study will be of interest to geotechnologists and others who are involved in nondestructive bridge condition assessment. The U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document. The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement. This research project was funded to investigate the possibility that, by measuring and modeling the dynamic response characteristics of a bridge substructure, it might be possible to determine the condition and safety of the substructure and identify its foundation type (shallow or deep). Determination of bridge foundation conditions with this approach may be applied to quantify losses in foundation stiffness caused by earthquakes, scour, and impact events. Identification of bridge foundation type may be employed to estimate bridge stability and vulnerability under dead and live load ratings, particularly for unknown bridge foundations. in inches 25.4 millimeters mm ft feet 0.305 meters m yd yards 0.914 meters m mi miles 1.61 kilometers km