DAMAGE DETECTION OF REINFORCED CONCRETE STRUCTURE BASED ON LIMITED STRONG MOTION RECORDS

The author presents one simplified technique and methodology for structural parameter identification and global damage detection from limited number of strong motion records. The time-invariant and time-varying parameters of structure are identified by using the off-line system identification method ARX and the on-line system identification method RARX respectively. The presence of damage is detected primarily by checking the changes of parameters during the earthquakes. Then, one procedure is introduced to convert MDOF structural system to equivalent SDOF system. The integral damage level of the equivalent SDOF system is detected by using the ductility factor and damage index. The damage index of the equivalent SDOF system can be considered as the integral damage level indicator of the MDOF system. The method is applied to Hachinohe City Hall building which was lightly damage in the Sanriku-oki Earthquake on Dec. 28, 1994. The parameters of the building are identified and the damage level is detected from the strong motion records. The results show that the method has with high efficiency, validity, applicability and practicability. The method can be implemented to assess the structural damage level and to judge if the damage is repairable or not after a big earthquake. Furthermore, the method can be used to predict the failure of a whole structure and to evaluate the performance in earthquake. The presented technique and method can be considered as a significant aid for making structural retrofitting decision after devastating earthquake.