Seismic Assessment of A Retrofitted Chimney By Fem Analysis and Field Testing

The Chi-Chi Earthquake that struck Taiwan in 1999 damaged a 250 m tall chimney located in central Taiwan. To understand the dynamic behavior, failure trigger mechanism, and seismic performance of the chimney that has been rehabilitated, a study using experimental and analytical approaches was carried out. The ambient vibration test, together with a system identification approach, was used to evaluate the dynamic characteristics of the chimney. A subspace approach with an instrumental variable concept was used in the system identification. The dynamic behavior of the chimney was also simulated by a 3D finite element analysis using the commercial software SAP2000. Finally, the design code of ASCE 1975 was adopted to check the buckling capacity of the steel flues in the chimney structure. The results indicated that the calculated stresses correspond well with the actual damages observed in the steel flues.