Keywords: optimization, location of dampers, damping constants, viscous dampers.

The control of vibrations by viscous dampers has been used in civil engineering to reduce vibrations caused by winds and earthquakes. The good locations for dampers in the structure and the optimal damping constants are important parameters of damper systems. When excitation forces are known, forced responses can be determined for different locations of dampers and different damping constants. Moreover, some optimization procedure which minimize displacements or accelerations can be used in the search for the optimal configuration of dampers. If the excitation forces are not well defined the other design criteria in which the modal damping level of specific modes of vibrations is often used. Reference [1] follow in this direction. The second approach to optimization of damper locations and damping constants is utilized in the current paper.

In this paper, the objective function which must be maximized is chosen in the form of sum of the weight factors multiplied by the non-dimensional modal damping factors.

The weight factor could be chosen more or less arbitrarily or it could reflect the influence of the each mode of vibration on a chosen quantity which characterizes the dynamic response of structures.

In the paper, four versions of the objective functions are chosen. In the first case, the non-dimensional damping factor of the first vibration mode is maximized. In the second case, the values of weight factors are equal to the values of modal contribution factors of the top storey displacement whereas, in the third case, the values of weight factors are equal to the values of modal contribution factors of the shear force on the first storey. In the fourth case, the values of weight factors reflect some global characteristic of the structure.

Two types of constraints are introduced. The total amount of the damping factor values of the dampers to be distributed on the structure is fixed. Moreover, the damping factor of damper must be a positive number not greater than the prescribed value.

The sequential linear programming method is used to solve the optimization problem. It is found that the required iteration procedure is very fast and can efficiently solve the considered problem. The suggested optimization approach to optimize the positioning of the dampers and tuning the dampers factors is much simpler than other approaches.

Building structures are considered as exemplary calculations. The results of the analyses are described and compared with ones available in the literature.

1

E. Engelen, H. Ramon, W. Saeyes, W. Franssens, J. Anthonis, "Positioning and tuning of viscous damper on flexible structure", Journal of Sound and Vibration, 304, 845-862, 2007. doi:10.1016/j.jsv.2007.03.020

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £145 +P&P)