DEVELOPMENT AND EXAMINATION OF FORCE SPECTRA FOR CONSTRUCTION MACHINES

Abstract

Together with our partner Baudynamik Heiland & Mistler the university of Applied Sciences is developing a practical prediction method for construction machine induced vibrations. The project is sponsored by BMWi. The new method takes the construction machine parameters and the soil characteristics much more realistically into account. This is done by a special measuring procedure. The first step of this procedure is to measure the transfer admittance of the specific machine at a location „1“ and the vibration responses at different distances. Then the machine spectra are calculated from the measured data at each distance. In a second step the transfer admittance i.e. in building (location „2“) are measured for an impulse force induced by a special impulse generator. Then the previously obtained machine spectra together with the impulse response is mathematically transformed in the frequency domain to obtain a prediction of the vibrations in the building caused by the machine by back transformation in the time domain. The so predicted vibrations can be used to evaluate the admissible vibration given DIN 4150-3. The two step procedure is based on the assumption that the vibrations transfer in the soil and in the building can be described as linear systems. Within the paper this assumption will be proofed for a specific vibration plate. The procedure describe above is applied to three different places with completely different soil characteristics. The machine force spectra are obtained for each soil at different distances. The data evaluation shows the significant influence of the distance to the calculated machine spectra. The influence of the impulse level (lower or higher impulse forces) shows to be of minor significance. A comparison of the force spectra obtain for the three different soils shows that the machine spectra are in satisfactory accordance. As result it can be stated that the assumed of linear vibration transfer for vibrations caused by the vibration plate can be satisfactorily proofed. The proposed prediction method is further developed and proofed.