Rapid identification of properties of column-supported bridge-type structure by using vibratory response

Some engineering structures, such as bridges in transportation network, may be subject to unexpected hazardous events, which calls for the rapid identification of their structural properties using portable hardware and data analysis system to evaluate their remaining load-carrying capacity. A significant challenge in such mission is the lack of baseline information of the structure to be evaluated. In this research, we formulate a vibration-based methodology using modal testing to identify properties of column-supported bridge-type structure. An assumed-mode based discretization is adopted to establish an equivalent nominal model that is a function of the unknown structural properties. The system identification algorithm is built upon the mass response method, i.e., introducing a known added mass to the structure and measuring respectively the modal information before and after this mass is added. This approach enables the structural identification without a priori information of the mass. Systematic case studies are then carried out to evaluate the effectiveness of this methodology. It is found that the new algorithm formulated can yield very accurate and robust identification results.