Issues in multi-reference impact testing of steel-stringer bridges

A recommended methodology is presented for the condition assessment and structural evaluation of a highway bridge. Based upon the structural identification concept, this global NDE method employs the modal test technique of multiple reference impact testing as its principle experimental tool. Modal flexibility provides a conceptual, quantitative, comprehensive and damage-sensitive signature for the structure. A research project is underway to rigorously demonstrate and verify these experimental concepts and tools. A typical steel-stringer bridge will be subjected to a series of deliberately induced damage, simulating typical deterioration and damage scenarios which may affect steel-stringer bridges. For the baseline and subsequent damage scenarios, issues which may cause multi-reference impact testing to be an impractical experimental tool for bridge evaluation are identified and investigated. Quality control strategies which are intended to minimize experimental errors are developed and investigated as well.