EFFECT OF IMPOSED LOAD ON SOLID-SAWN WOOD-JOIST FLOOR VIBRATIONS

This paper characterizes the dynamic response of solid-sawn wood-joist floors as affected by live load level in terms of the following three parameters: natural frequencies, damping ratios, and frequency-weighted root-mean-square (RMS) accelerations. The acceleration and displacement traces from free-vibration and drop-weight tests are employed to correlate the live loads to the three parameters. Three levels of live loads are considered: 0 N/m(2), 957 N/m(2) (20 psf), and 1914 N/m(2) (40 psf). The experimental results showed that natural frequencies for given modes of vibration, the number of principal modes (modes with significant power associated with them), the spacing between adjacent modes, and frequency-weighted RMS acceleration decrease as the live load increases from 0 N/m(2) to 1914 N/m(2). The damping ratio does not show a clear trend as the live load was increased from 0 N/m(2) to 1914 N/m(2).