THRESHOLD CHANGES IN BUILDING FREQUENCIES OF VIBRATION ASSOCIATED WITH STRUCTURAL DAMAGE - STUDY OF FULL-SCALE OBSERVATIONS IN THE BORIK-2 BUILDING IN FORMER YUGOSLAVIA

摘要

A critical issue that has to be addressed before structural health monitoring systems can be implemented for real time earthquake damage detection and early warning is that the damage sensitive features may vary due to factors other than earthquake damage. This paper presents a case study of the response of a 14-story prefabricated RC building in Banja Luka, Republic of Srpska, to 20 earthquakes over a period of 12 years. The analysis shows consistency of the estimates of system frequency from the earthquake response data, from forced vibration tests before the earthquakes and ambient vibration test conducted near the end of the earthquake sequence. The results suggest nonlinear but essentially "elastic" behavior of the building for the amplitudes of motion covered by the data, and essentially linear soil-structure interaction.