Mihai Negru

Influence of Non-Linear Properties of Fluid Viscoelastic Properties on Seismic Damping Properties of a Ten Stories Building Using ANSYS Program

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.

Optimal Configuration of Fluid Viscoelastic Seismic Dampers on a Ten Stories Building Using Finite Elements Method

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.

Network Seismic Capability Assessment of Power High Voltage Electric Equipment

The good operation of the power system should be ensured under normal and limit operating conditions as well as in case of seism or short-circuit events. From this point of view, special problems appear at the switching equipment with column type construction such as high voltage circuit breakers. At this type of equipment, due to their characteristic construction and specific tasks to carry out, depending on the location in the network, network topology and type of switching events the mechanical stress can vary over a very wide range. These events have cumulative effects and are leading, over time, to weariness of the structure and a seism or serious short-circuit, due to their violent actions, can have destructive effects. Consequently, with a view to ensure a high reliability, it’s a good idea that the principal switching equipments should be subject of some experimental tests in order to assess their capability to stand out to future events.

Validation of GenEcAm Software Results in Simulation of Seismic Behavior of Buildings Equipped with Damping System

This paper presents the validation process of the GenEcAm program made by the author by comparing the results obtained with this program with the results obtained with the SAP2000 program at the dynamic analysis of a P+10E building equipped with viscous fluid dampers, one on each facade on each level. The results obtained with these two programs are very close, which validates the correctness of the analytical and computational model that underpinned the creation of the GenEcAm program. The GenEcAm program allows the use of 9 theoretical models of hysteresis to simulate seismic behavior of the dampers that equippe the structure of a building.

Comparison of the Results Obtained in Simulation of SERB Dampers Using Two Different Hysteresis Models

This paper presents the difference between the results obtained with GenEcAm in simulating the seismic behavior of a P + 10E building equipped with SERB dampers modeled with two hysteresis models, namely the classic Bouc-Wen model and a Bouc-Wen modified model Bouc-Wen_Exp, in order to highlight the most appropriate theoretical model for modeling these dampers. The GenEcAm program is created by the author for the dynamic analysis during seism for structures of buildings equipped with different earthquake damping systems, with the possibility to use 9 different theoretical models of hysteresis for simulating the hysterical behavior of seismic energy dissipation devices that fit the antiseismic system of the analysed building.

F.E.M. Simulation of the Building Frame Node Behavior during Seism

This paper presents a simulation made with ANSYS program on the stress and strain state of the node region of a reinforced concrete building subjected to earthquakes and equipped with devices for seism energy dissipation. This simulation includes the forces developed by the damping devices which act on these important nodes regions. The main goal of this simulation is to determine if the presence of the damping device at the supra-structure of the building is increasing the stresses and strains in the concrete and reinforcement bars of the node during earthquakes. For this study were used damping devices with damping forces depending on displacements. The results are very useful in the process of designing the damping system for the superstructure of the building and in the process of designing the reinforcements of the building nodes regions.

The Comparison between Viscous Fluid Dampers and Romanian Friction Dampers Performance in Base Isolation System of Buildings

This paper analyse the performance of two types of devices used for protecting the building against collaps during earthquakes. These devices are used in paralell with the base isolation system of the building and are intended to increase the damping phenomenon in order to dissipate the quakes energy received by the resistance structure of the buildings. The purpose of this computational study is to determine if these friction dampers, which are four times less expensive than the classical viscous fluid dampers, can replace the classical choice in order to obtain a less expensive protection. The results obtained at the final of this study are encouraging because the damping performances of romanian telescopic devices are similar with the performances of classical viscous fluid devices in base isolation system.

F.E.M. Parametric Model Optimization of SERB-194C Device Used in Buildings Drift Limitation System

In this paper is presented a new parametric finite elements model of SERB-194C [1] device which is used in protecting the civil engineering structures during earthquakes by limitating the drifts of building stories and dissipating the energy received by the building structure during the earth surface shaking. The goal of this simulation is to determine the influence of the device components dimensions on the variation of forces-displacements device curve. Modifying the device components dimensions, the force-displacements device curve is changing the shape and the area which are related with the capacity of building drift limitation of SERB-194C device. By changing the hysteretic loop shape and dimensions this device can be optimized for different buildings and structures in order to properly diminish the story drift during ground shaking.

Adapted Bouc-Wen Analytical Model for Romanian SERB-C Seismic Dampers Used in Buildings Protection System

In this paper is presented a new mathematical model which is intended to simulate the hysteretic phenomenon of SERB-C Romanian friction device for damping and dissipation of earthquake energy used for buildings. These devices have unusual shape of force-displacement loop which can be simulated with our new model which represents a specific adaptation of the well known Bouc-Wen hysteretic model. The purpose of this analytical simulation is to determine a relation for the hysteretic loop which was obtained by experimental tests performed by the authors. The mathematical model presented in this paper can be used in computational simulation of a building protected with these types of devices, in order to determine the anti-seismic performances of a Romanian friction building protection system.