Vibration Mitigation in Bridges Using Integrated Semi-Active Control Concepts

Abstract eng:
Passive control is extensively used in bridges today for mitigation of seismically induced vibrations mostly due to its low cost to effectiveness ratio. Passive control is, however not always applicable and active or semi-active control concepts have to be used especially in large bridges. Semi-active control means that certain key parameters of the control device in a system like friction or flow of magnetorheological fluid are controlled. It offers the possibility to further improve the seismic performance of bridges with little additional effort, especially in large bridges where the low maintenance costs are a major advantage of semi-active control when comparing to active control. Except for the mitigation of seismically induced vibrations in bridges, semi-active control can also be used for mitigation of vibration coming from other sources. One example for this is the use of semi-active TMD-s in pedestrian bridges that enable more slenderness and lower construction cost for these bridges. This shows that semi-active control could be also used as integrated vibration mitigation control for not only earthquakes but also wind and traffic induced vibrations. In order to test the effectiveness of different integrated semi-active control strategies a test setup has been built at the University of Kassel. It consists of a cylinder that is connected to a movable steel construction underneath a semi-active device, which represents a single DOF of the structure. The constraint to just one DOF is not limiting because through the use of hybrid simulation this DOF and with it the semi-active device can be moved to any feasible location in a numerical model of the bridge. The semi-active device can be frictional, magnetorheological or any other. In the first step it is important to validate the feasibility of hybrid simulation in semi-active control development. In order to do this the results of hybrid simulation experiments will be compared to a real world shaking table tests conducted at IZIIS Skopje. The tested bridge was a scaled down model of a deck bridge with two piers on which UHYDE-fbr devices were placed in order to simulate different passive devices. UHYDE-fbr device is a patented semi-active bi-directional friction device. The friction force in the device is controlled through the change of air pressure in the device chamber. The same device as in the shaking table experiments will be used in the hybrid simulation experiments for comparison. Research will further concentrate on developing different semi-active control strategies for bridges. Different control algorithms like H2/LQR algorithms will be tested on the existing numerical model of the tested bridge and also on the ASCE Cape Girardeau benchmark cable-stayed bridge model. The final goal is to develop integrated semi-active control concepts and a hybrid simulation environment for the testing of the developed concepts. First results and conclusions of this on-going research will be presented.

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