The effectiveness of passive dampers in reducing bridge vibrations

Abstract

To reduce the dynamic response of superstructures from the impact of a moving load, one of the main methods used in the established practice is to regulate the mass of superstructures, as a rule, in the direction of increase. In this approach, an important role is played by the analysis of dynamics of the rolling stock – superstructure system. Another way to reduce the dynamic response of the rolling stock-superstructure system is to install special damping devices, both passive and active. The use of an active damper makes it possible to achieve maximum effect in reducing vibrations, however, the design of such a damper has a certain complexity, is expensive and unreliable in operation. Currently, it is more economical to use passive type dampers with self-contained properties.
The article discusses various options for using dynamic vibration dampers in different systems. The goal of the research is to predict and optimize the use of these dampers in order to minimize any negative effects on bridge structures.
Vibration isolation systems that use dynamic vibration dampers can achieve maximum efficiency if key control parameters are carefully selected and optimized. These parameters include: the frequency range, the ratio of tuning frequencies, the amount of damping, and the number of dampers used in the vibration isolation system for the bridge. If these parameters are not selected correctly, the system may not function optimally and may not provide the required level of vibration reduction. To optimize these parameters, the vibration dampers should be placed symmetrically relative to the center of the bridge, with a certain spacing.
Based on the analysis, it is shown that the effectiveness in reducing bridge responses decreases with increasing interval between dampers and when installed further from the middle. The most massive damper is located in the middle of the span, and as you move away from the center, the mass of the dampers decreases. The maximum number of dampers is determined by the length of the bridge and the pitch of their installation. It is important to note that as their number increases, the optimal values of the tuning range and frequency ratios increase.