Assessment of Damage in Seismically Excited RC-Structures from a Single Measured Response

A method has been developed for the localization of structural damage of substructures of seismically excited RC-structures using only the ground surface acceleration time series and a single response time series. From the response, the smoothed two lowest eigenfrequencies are estimated. The distribution of local damage are the performed in such a way that these smoothed eigenfrequencies are reproduced. The local damage indicators for a certain substructure are defined as the average reduction of the stiffness matrix of the initial undamaged substructure. These damage indicators are identified by a sequence of substructures, where two new substructures are introduced at each level, so that the smoothed eigenfrequencies are reproduced at each level. The method is applied to simulated data of a 1-bay, 2-storey RC-frame and a 1-bay, 4-storey RC-frame generated by a finite element programme developed for RC-frames which also admits an estimation of local damage. Based on the response time series calculated by the finite element programme, the corresponding local damages are next calculated by the present method. The method is investigated at different intensities of the earthquake and upon comparison with the finite element predictions it is found that the method is very efficient in localizing the damage when the damage level is sufficiently high. Furthermore, it has been experienced that the method seems to get slightly more inaccurate with increasingly structural complexity, i.e. the damage localization can only be driven to a certain limit due to the limited amount of information in the single response times series.