Joint work of a flat frame and pile foundations under dynamic impacts

Abstract

In this paper, the basic data of theoretical and experimental studies of a flat frame on pile foundations are presented. Based on theoretical and experimental studies, methods for conducting experimental studies have been developed, the dynamic parameters of the system have been determined, the dynamic calculation scheme has been refined, and a method for calculating a flat frame with a pile foundation under dynamic loads has been developed. Calculation and comparative analysis of the results on the application of pile foundations following building standards are made and the advantage of the work of pile foundations under the condition of dynamic effects is established. Research results allow us to obtain the dynamic characteristics of a flat frame on pile foundations, necessary for subsequent calculations. An analysis of the modes of natural vibrations shows that for a system the 1st form of vibrations is apparently qualitatively different from the vibration form of a conventional single-mass system. To determine the degree of reliability of the developed methodology, the results of theoretical calculations carried out on the basis of the obtained formulas were compared with field tests for structures. The parameters used were adopted on the basis of theoretical calculations. Quantitatively, the discrepancy near the resonant frequency was about 15% in moving micron vs frequencies curves. The maximum amplitude of oscillations on this grillage very closely coincides with each other. With an increase in frequency in both cases, it leads to a decrease in the amplitude of oscillations of the grillage. The discrepancy between the theoretical and experimental values was about 16%.