Damage identification of a three-story infilled RC frame tested on the UCSD-NEES shake table

Reinforced concrete (RC) frames with masonry infill walls can be frequently found in areas of high seismic risk around the world. Such structures are often designed with older building codes and may experience catastrophic failures during earthquakes. A 2/3-scale, three-story, two-bay, infilled RC frame was tested on the UCSD-NEES shake table to investigate the seismic performance of this type of construction. The frame was designed according to the building practice in California in the 1920s. The shake table tests were designed so as to induce damage in the structure progressively through scaled earthquake records. At various levels of damage, low-amplitude white-noise base excitations were applied to the infilled RC frame, which responded as a quasi-linear system with modal parameters depending on the extent of the structural damage. In this study, the modal parameters identified from the white-noise test data acquired at various levels of damage are used to detect the existing damage. A sensitivity-based finite element model updating strategy is employed to detect, locate, and quantify damage at each damage state considered. This paper presents the results of the damage identification study, which shows that the method can accurately identify the location and severity of damage observed in the tests.