Multi-modal Passive-vibration Control of Bridges under General Loading-condition

Application of TMD systems are observed for mitigation of excessive vibration of bridge-structures targeting either wind loading or vehicle loading. Usually, dominant modes in one direction (commonly vertical) are taken in account for such passive control using TMD systems. However, considering modes dominant in one direction may not be considered as a robust practice while any bridge structure is having dominant modes along both the transverse and vertical directions and the same bridge structure is subjected to loading along both the directions. An approach for simultaneous control of major horizontal, vertical and torsional modes is presented in the present study targeting robust vibration control under general loading condition. A modal frequency response function (FRF) based strategy is proposed using the traditional mode-wise control approach. The proposed modal FRF based approach is applied to an existing important large truss bridge (Saraighat Bridge) to carry out an analytical design of TMD system considering general loading conditions. A Good control-performance is observed based on this proposed design methodology under various simulated general loading conditions.