Seismic damage assessment of RC structures under shaking table tests using the modified direct stiffness calculation method

The modified direct stiffness calculation (DSC) method for application to damage detection of RC frames based on the stiffness variation index (SVI) is comprehensively studied. Judging from the fact that few techniques were successfully applied to field problems, the objective herein is to apply the modified DSC method to RC frames, and to ensure that it really works. The vibration data recorded of a 12-story RC model frame under a series of shaking table tests (62 scenarios under four earthquakes of various levels) were adopted. The SVI adopted is based on two key parameters: (1) the modal curvature, which is more sensitive to structural damage than the mode shape frequently used, and (2) the modal moment, which is rather insensitive to ambient noises, as it is calculated from the force equilibrium condition. By comparing the present results with those based on a typical index (MDLAC) and the damage status of the frame in the tests, it is concluded that the modified DSC method, along with the SVI, can be reliably applied to the damage detection of RC frames in practice.