UBC Theses and Dissertations
Vibration of lightweight wooden floors : experimental and analytical evaluation Neumann, Greg A.
An experimental study of two lightweight wooden floors’ dynamic response was per formed. The objective of this study was to evaluate the applicability of the computer programs, NAFFAP and DYFAP, for the case of lightweight wooden floor vibration. The program NAFFAP solves for the floor system’s natural frequencies and mode shapes while DYFAP performs a time domain integration of the equations of motion in response to a specified loading on the floor. DYFAP also has the capacity to model the coupled response of oscillators upon the floor system. These programs employ a T—beam finite strip analysis. The test data of the floors’ dynamic response to various impacts were compared with the programs’ simulations. One floor used 2x8 sawn lumber joists while the other used composite wood I—Joists. The transient dynamic response of the two floors to three types of excitation were recorded. The three types of excitation were created by a hammer tap, releasing a sand filled bag and a standard human heel drop. The modelling of a human occupant with a single degree of freedom oscillator, the International Standards Organization’s two degree of freedom oscillator model and a forcing function were investigated with DYFAP. The oscillators were composed of lumped masses, springs and viscous dashpots. The program NAFFAP was sufficiently successful in predicting the floors’ natural frequencies. The floor parameters that were used with NAFFAP were then used with DYFAP to produce displacement time histories that compared well with the test data. DYFAP’s modelling of occupants with simple oscillators rather than a forcing function proved to be appropriate.
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