The research described in this paper focused on the application of modal strains on a multi-girder bridge superstructure, with the objectives of identifying the presence of damage, and evaluating the performance of Mindilin approach for such structures. The case study is a one-third scale model of a slab-on-girder composite bridge superstructure featuring four steel girders supporting a steel-free concrete deck, based on the North Perimeter Red River Bridge in Winnipeg, Manitoba. The modal test data acquired through the application of damage sce-nario and analyzed by some mathematical procedures and Mindilin approach. The Mindilin approach uses a small number of sensors and only the fundamental mode of vibration to ob-tain the modal strains. The efficiency of two normalization schemes for obtaining the Mindilin strains was studied. The unit-area normalization method process produced a more precise damage patterns based on the Mindilin approach than the widely used unit-norm method. The Mindilin modal strains obtained from unit-area normalized fundamental mode shape, yields promising results in locating damage in the multi-girder bridge structures.

Keywords