Structural control systems in high speed railway bridges Structural vibration control of high speed railway bridges using tuned mass dampers semi active tuned mass dampers fluid viscous dampers and magnetorheological dampers to reduce resonant structural vibrations is studied. In this work the addressed main issues include modeling of the dynamic interaction of the structures optimization of the parameters of the dampers and comparison of their efficiency. A new approach to optimize multiple tuned mass damper systems on an uncertain model is proposed based on the H infinity optimization criteria and the DK iteration procedure with norm bounded uncertainties in frequency domain. The parameters of tuned mass dampers are optimized directly and simultaneously on different modes contributing significantly to the multi resonant peaks to explore the different possible combinations of parameters. The effectiveness of the present method is also evaluated through comparison with a previous method. In the case of semi active tuned mass dampers an optimization algorithm is derived to control the magnetorheological damper in these semi active damping systems. The use of the proposed algorithm can generate various combinations of control gains and state variables. This can lead to the improvement of the ability of MR dampers to track the desired control forces. An uncertain model to reduce detuning effects is also considered in this work. Next for fluid viscous dampers in order to tune the optimal parameters of fluid viscous dampers to the vicinity of the exact values analytical formulae which can include structural damping are developed based on the perturbation method. The proposed formulae can also be considered as an improvement of the previous analytical formulae especially for bridge beams with large structural damping. Finally a new combination of magnetorheological dampers and a double beam system to improve the performance of the primary structure vibration is proposed. An algorithm to control magnetorheological dampers in this system is developed by using standard linear matrix inequality techniques. Weight functions as a loop shaping procedure are also introduced in the feedback controllers to improve the tracking ability of magnetorheological damping forces. To this end the effectiveness of magnetorheological dampers controlled by the proposed scheme along with the effects of the uncertain and time delay parameters on the models are evaluated through numerical simulations. Additionally a comparison of the dampers based on their performance is also considered in this work.