DYNAMIC TESTING PROCEDURES FOR HIGHWAY BRIDGES USING TRAFFIC LOADS

Dynamic bridge testing techniques used at the University of Sherbrooke on a series of highway bridges in the province of Quebec, Canada, are presented. These procedures were developed to obtain a reliable evaluation of the dynamic amplification factor for existing bridges, as part of an ongoing rehabilitation program of the province's road network. Vertical acceleration responses are obtained under normal or controlled traffic using different test vehicles and loading patterns. The vibration frequencies and mode shapes are calculated from a frequency analysis of the measured data, and used to calibrate finite-element models for each structure. The experimental methods and data-processing techniques are described. The need to establish standard testing procedures is discussed and some recommendations are presented. Examples of test results and comparisons with finite-element eigenvalue analyses are given for three different bridges.