Damage assessment through structural identification of a three-story large-scale precast concrete structure

This paper investigates the damage assessment of a three-story half-scale precast concrete building resembling a parking garage through structural identification. The structure was tested under earthquake-type loading on the NEES large high-performance outdoor shake table at the University of California San Diego in 2008. The tests provide a unique opportunity to capture the dynamic performance of precast concrete structures built under realistic boundary conditions. The effective modal parameters of the structure at different damage states have been identified from white-noise and scaled earthquake test data with the assumption that the structure responded in a quasi-linear manner. Modal identification has been performed using the deterministic-stochastic subspace identification method based on the measured input-output data. The changes in the identified modal parameters are correlated to the observed damage. In general, the natural frequencies decrease, and the damping ratios increase as the structure is exposed to larger base excitations, indicating loss of stiffness, development/propagation of cracks, and failure in joint connections. The analysis of the modal rotations and curvatures allowed the localization of shear and flexural damages respectively and the checking of the effectiveness of repair actions. Copyright (c) 2013 John Wiley & Sons, Ltd.