Damage Detection in Prestressed Concrete Slabs Using Wavelet Analysis of Vibration Responses in the Time Domain

Abstract

Detection of damages in structures during their service life is of vital importance and under attention of researchers. In this paper, it is attempted to identify damages in prestressed concrete slabs using vibration responses obtained from modal testing in the time domain. For this purpose, first some damage scenarios with various geometric shapes and at different locations of numerical models, corresponding to a prestressed concrete slab, were created. Next, the impact hammer force in the modal test was simulated and the accelerations time histories at different degrees of freedom corresponding to the numerical models per two states of damaged and undamaged structure were selected as the inputs for a number of damage indices to identify the damage locations. Some of these damage scenarios have been located at the middle of prestressed concrete slabs and some at the corners. The proposed damage indices in this research are obtained based on the area under the diagram of acceleration time histories, maximum and also the area under diagram of detail coefficients of the wavelet transform using the three wavelet families of Daubechies, Biorthogonal and Reverse Biorthogonal. The results showed that using damage index obtained from the area under diagram of detail coefficients of wavelet transform with the mother wavelet db2 could detect the damage scenarios at the middle and corners of the slab with a well precision. Furthermore, the damage scenarios at the corners of numerical models could be detected properly by using the mother wavelet rbio2.2 in the proposed damage index.