Dynamic identification and damage detection of a RC building subjected to earthquake excitation

In this paper are presented the results of an experimental study concerning the dynamic identification and the damage assessment of a real building. The considered structure is the building of the Civil and Environmental Engineering Department at NCHU in Taichung which was subjected, between July 1998 and November 1999, to the Chi-Chi Earthquake main shock and numerous foreshocks and aftershocks. The building is instrumented by a monitoring system composed of 29 accelerometers. The dynamic identification is, first, performed through the FDD (Frequency Domain Decomposition) method by using only the output records according to the Operational Modal Analysis. Then, the OKID-ERA/DC time domain algorithm is applied as well, using the output accelerations together with the other available records considered as input base accelerations. Based on the identification results, some linear and nonlinear damage indexes are applied providing an indication about the presence and location of damage. The main goal of the investigation is to test the efficacy of the analysed identification techniques and damage indexes in a real case.