Determination of the natural periods of buildings

Abstract

abstract Random wind excitation has been used to find the first three modes of vibration of a nineteenstory building about the two major translational axes and the torsional axis of the building. Vibration records were obtained with Willmore electromagnetic seismometers feeding into a multichannel magnetic tape recorder. A harmonic analysis was then performed with the aid of an analogue computer to determine the first few vibration modes. Concurrently with the experimental program the building modes were computed two ways using different simplifying assumptions regarding the lateral stiffness of the structure.