Experimental algorithm for detecting damage applied to the I-40 bridge over the Rio Grande

An algorithm originally used to locate errors in finite element models is applied to a full scale bridge damage detection experiment. The method requires experimental frequency response function data measured at discrete locations along the major bridge load paths. In the bridge damage application the algorithm is most effective when applied to static flexibility shapes estimated with a truncated set of six mode shapes rather than individual mode shapes. The algorithm compares `before damage' and `after damage' data to locate physical areas where significant stiffness changes have occurred. A damage indicator shows whether damage is detectable. Damage is correctly located in the two most significant damage cases using the driving point static flexibility estimates. Limitations of the technique are addressed. The damage detection experiment was performed on a three span steel girder bridge that was 425 feet long. This bridge was part of Interstate 40 across the Rio Grande. The New Mexico State University Department of Civil Engineering organized the experiment. The frequency response functions were collected by Los Alamos National Laboratories personnel. The bridge excitation was provided by Sandia National Laboratories.