Vibration-proof Designing for Machine Support Systems - Study on Floor Vibration Interaction and Force Identification

摘要

Protecting buildings from flood hazards is one of the most important issues facing planners of waterfront development projects, which are becoming popular in Japan. Machinery critical to the use of a building is commonly placed on upper floors, where it sometimes bothers occupants of buildings by generating vibration and/or structure-borne sound. In dealing with vibration-proof analysis of floor structures, two important points are often overlooked. Firstly, the vibrational interactions between machine supports and floor structure are commonly not considered, that is, the vibration transmission ratio is calculated for a single-degree-of-freedom (SDOF) analysis model; and this may cause errors in predicted values. Secondly, the excitation force characteristics of the machines are often not clearly identified, and as the result is that the predicted response does not agree well with measured data. In this paper, numerical models of machine support systems, including floor structures, are presented to improve vibration prediction. Further, by examining actually measured data, the properties of these numerical models and the excitation forces used for vibration prediction are discussed for the case of emergency power generators.