This work introduces a modal testing and analysis results of the mock-up for a layered stone pagoda. The pagoda has been horizontally excited by an impact hammer. As to the measured acceleration time responses, the first five lower mode shapes and natural frequency are extracted by the TDD technique. It is observed that the time delay of a shear wave occurs through friction surfaces. Such phenomena cannot be described by using the traditional analytical models such as a continuum cantilever beam model or a discrete shear building model. However, the time delay typically affects only the phases of the pagoda system. The frequencies of the pagoda system are not affected by such time delay. It is found in the first time that the layered stone pagoda system has a set of closely placed modes in near of natural frequency. It is believed that such modes are due to the friction characteristics in friction surfaces. Based on the stick-slip friction model, it seems that the one of the closely placed mode can be a self-excited one.

1. 서 론
 2. TDD 기법
  2.1 공간 변수의 추출
 3. 석탑의 동특성 추출
  3.1 실험 개요
  3.2 응답신호의 시간지연
  3.3 모드형상의 추출
  3.4 고유진동수와 감쇠비
 4. 요약과 결론
 / 감사의 글 /
 / REFERENCES /

• 김병화(경남대학교 토목공학과) | Kim, Byeong Hwa
• 문대중(㈜이제이텍) | Moon, Dae Joong
• 이도형(배재대학교 건설환경철도공학과) | Lee, Do Hyung Corresponding author