ANALYSIS OF VIBRATION CHARACTERISTICS OF HISTORICAL MASONRY BUILDING WITH REINFORCED CONCRETE FLOORS BASED ON MICRO-TREMOR MEASUREMENTS

Ambient vibration measurements on a historical brick building with RC floors determined its primary natural frequency and vibration modes. Comparing a simple multi-degree-of-freedom model with measurements revealed: 1) Unlike masonry buildings with wooden floors, which show significant out-of-plane displacement of central walls, this building exhibits translational vibration in both directions, indicating rigid floor behavior due to RC floors and tie beams. 2) The vertical mode shape is linear from basement to rooftop; a four-degree-of-freedom model matches measurements better than a three-degree one. Thus, when evaluating seismic performance of buildings with elevated first floors, basements should be treated like above-ground floors.