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RESEARCH PRODUCT

Experimental Investigation of Random Vibration Control Through Dry Friction

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The purpose of this experimental investigation is to measure the response statistics in the presence of base friction and other friction sources. The experimental model emulates a one-floor building supported on four leaf springs, subjected to band limited random excitation. Two different types of model base are considered, a friction base and a frictionless base. In both cases friction can also be applied at two sides of the model’s main mass against the direction of its motion. Excitation and response transducer signals are processed to estimate excitation and response statistics in the presence and in the absence of top mass friction. Measured statistics include mean squares, autocorrelation functions, power spectra, and probability density functions. The dependence of the mean square response on the excitation level in the presence of friction reveals linear and nonlinear regimes, as well as a drift in the response due to dry friction. Above a certain excitation level the response-excitation relationship displays nonlinearity. A transition from narrow band to wide band response spectra is observed when friction is applied to the system’s top mass. The results of this investigation are of interest to civil engineers involved in the structural safety of buildings situated in regions susceptible to earthquakes (Feng, et al, 1993).