For a building equipped with anti-seismic devices, the value of the damping force of the dampers positioned at the superstructure is very important for an efficient anti-seismic damping and therefore an optimization of the seismic protection system with dampers is required. There are several configurations for placing the dampers that amplify the displacement and the damper axial force. This paper presents a computational mathematical model made for determining the coefficients of displacement multiplication and the damping force multiplication for two special positioning configurations of the antiseismic dampers using levers. Based on this model, a software program was created that allows to choose the geometrical parameters of two configurations of dampers placement having as criterion of choice the value of the amplification coefficient of the dampers displacement or the damper axial force.

This paper presents a study made in order to find different optimal configurations of positioning fluid dampers on high buildings for dissipating the seismic energy. The study was made using Finite Elements Method and ANSYS program, on a ten stories building structure. The first step of this optimization process is to consider the fluid dampers having linear damping properties in order to achieve a quicker convergence of the solutions. In order to obtain the influence of the dampers configurations on the structure damping there were made multiple different configurations of dampers positioned on different locations on the building. All these models were analyzed using modal analysis and it was obtained the modal damping of the building structure for the first vibration modes of the structures for each configuration. The graphics obtained can be used for achieving different degrees of seismic energy dissipation for the analyzed building.

This paper presents the simulation of the influence of viscoelastic fluid dampers, with nonlinear damping properties, on damping property of a ten stories building structure. The study was made using Finite Elements Method and ANSYS program, on a 3d F.E.M. model. In order to obtain the influence of different types of damping nonlinearities of the viscoelastic fluid dampers on the damping property of the entire structure, there were made different types of simulations using modal analysis and seismic time history analysis. The graphics obtained can be used for determining the nonlinear features of fluid dampers for achieving different degrees of seismic energy dissipation for the analyzed building.

This paper presents a new Stiffness Relaxation method of the classic Bouc-Wen hysteresis model, used to simulate the hysteresis loop of Romanian friction dampers SERB-C-194 in seismic analysis of buildings equipped with this type of seismic dampers. The classic model does not accurately simulate the hysteresis loop of friction dampers because it keeps constant the stiffness of the damper as its stroke increases. Friction dampers are devices that strengthen the stiffness as the damper stroke increases. The proposed new method aims to simulate a stiffer damper but which is affected by the phenomenon of Stiffness Relaxation. Such methods have been proposed by Sivaselvan and Rheinhorn [1,2] which have introduced a Stiffness Relaxation factor R k which only works for the situations of continuous increase of the damper stroke. Our method offers a way to solve this problem by an "envelope" of the damper displacements. In this case the hysteresis loops of the new model are in accordance with the real situation observable in the hysteresis loops obtained experimentally. The new differential hysteresis model was implemented in the HistPlot program developed by the authors and is useful in determining the parameters of the differential model for simulating experimental hysteresis loops. This improved model is further used for earthquake dynamic simulation of buildings equipped with anti-seismic dampers using the GenEcAm program developed by the authors.

In this paper is presented a new mathematical differential model used for simulating the hysteresis phenomenon of romanian seismic energy dissipating devices which are usefull in seismic protection of buildings suprastructure. Existing mathematical models do not provide adequate modeling of the behavior of these devices during seism. The new mathematical model proposed in this paper represents a modification of the Bouc-Wen differential mathematical model through a new Strength Degradation method that reduces the capacity of the Backbone curve of the hysteresis characteristic. This is done through a yield force whose expressions have been proposed by several authors, but the new expression of the yield force proposed in this paper ensures an adequate simulation of the seism behavior of the Romanian anti-seismic devices SERB C-194. The new expression of yield force depends on four variable parameters that amplify the versatility of this new mathematical model which can simulate a wide variety of hysteretic loops difficult to model with other mathematical models of hysteresis.