Identification of damage parameters of a full-scale steel structure damaged by seismic loading

Within the European research cooperation COST a two-floor steel frame was defined as a benchmark directed towards investigating damage detection methods based on structural dynamic test data. In the present paper we describe an approach to identify the location and the extent of the damage introduced into the steel frame by pseudo dynamic seismic loads. In the first step the measured dynamic response of the original undamaged structure was used to generate a reference finite element model of the structure. In the next step the experimental modal data of the damaged structure were used to identify the location and the extent of the damage. This was based on comparing the changes of stiffness parameters obtained from the undamaged and the damaged structure. After careful selection of the parameters representing best the possible stiffness degradations the numerical values of the parameters were identified by minimizing the test/analysis differences of eigenfrequencies and mode shapes while simultaneously keeping the parameters within physically meaningful limits. With the identified parameters the finite element model was able to reproduce the experimental data as close as possible.