SEISMIC INTERFEROMETRY FOR DAMAGE IDENTIFICATION OF LARGE SCALE MODEL OF RC SHEAR WALL STRUCTURE

Abstract

Structural Health Monitoring is essential when it comes to damage detection and quantification of civil infrastructure under dynamic excitations. Lately, seismic interferometry has been frequently used for damage identification of structures under earthquake excitations. The method uses data from vibrational sensors to detect changes in travel times of seismic waves propagating trough the structure. The propagating waves’ travel time between pairs of sensors (and consequently their velocity) is related to the local stiffness of the structure enabling to follow possible degradation caused by damage during an extreme event. In this study an analytical uniform Timoshenko beam model that accounts for dispersion due to bending deformation, was implemented for system definition and damage identification of a 3 storey, 1:2 large scale shaking table model. The model is coupled wall RC structure and it was tested in the dynamic testing laboratory in IZIIS, in the frames of SERA project. A full testing programme consisted of random excitation and shaking table tests with gradually increasing intensity of the input excitation. We collected the data consisted of accelerograms from the distributed accelerometers of all tests and recorded damages of the model after each test, defining four damage states. In our research we focus on fitting uniform Timoshenko beam model in the recorded response of the shaking table model after each test. The structure was modelled with large shear stiffness and its compressional wave velocity, cL, was identified and analyzed. We monitored the change in cL after each damage state and compared it with the shift in the fundamental frequency of vibration f1 as well as the observed damage to discuss on the effectiveness of the method. We concluded that it is possible to detect and quantify damages of the structure induced by the increasing earthquake amplitude in each test by wave propagation analysis.