Dynamics of a Structure with Viscoelastic and Friction Dampers (original) (raw)
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Earthquake response of adjacent structures with viscoelastic and friction dampers
Theoretical and Applied Mechanics, 2015
We study the seismic response of two adjacent structures connected with a dry friction damper. Each of them consists of a viscoelastic rod and a rigid block, which can slide without friction along the moving base. A simplified earthquake model is used for modeling the horizontal ground motion. Energy dissipation is taken by the presence of the friction damper, which is modeled by the set-valued Coulomb friction law. Deformation of viscoelastic rods during the relative motion of the blocks represents another way of energy dissipation. The constitutive equation of a viscoelastic body is described by the fractional Zener model, which includes fractional derivatives of stress and strain. The problem merges fractional derivatives as non-local operators and theory of set-valued functions as the non-smooth ones. Dynamical behaviour of the problem is governed by a pair of coupled multi-valued differential equations. The posed Cauchy problem is solved by use of the Gr?nwald-Letnikov numerica...
The focus of this paper is the determination of dynamic parameters for structural systems with fractional viscoelastic (VE) dampers installed on them. The structures are treated as linearly elastic systems, subjected to earthquake-induced ground motion. Fractional Kelvin and Maxwell models with three or four parameters are used. These models, apart from stiffness and damping coefficients, are defined by the number representing the order of fractional derivatives. It is the aim of the study presented in this paper to establish a criterion, enabling the comparison of various damper models so as to obtain same or similar dynamic parameters of systems with different damper models.
Dynamic Response of a Structure to Earthquake Excitation
2017
Nenad Grahovac 1 Dragan Spasić 2 Miodrag Žigić 3 Aleksandar Okuka 4 UDK: 624.042.7:517.9 DOI:10.14415/konferencijaGFS2017.030 Summary: Behavior of a column like structure during earthquake excitation is studied. The structure consists of rigid blocks which move translatory during a horizontal ground motion. Fractional derivatives are used within a constitutive model of а viscoelastic damper. Dry friction damping during relative motion of the blocks is also considered. Governing equations of motion of the structure subjected to a single component horizontal ground acceleration are derived. The posed problem is solved by use of mathematical tools for dealing with non-smooth mechanical systems containing fractional derivatives.
Vibrations in Physical Systems, 2020
The purpose of the work is dynamic analysis of passive dampers used in structural systems to reduce excessive vibrations caused by wind or earthquakes. Special systems are considered that contain inerter, i.e. device using rotational inertia, in combination with a viscoelastic damper. The so-called fractional models of viscoelastic dampers describe their dynamic behavior in a wide frequency range using a small number of model parameters. To describe material behavior over a wider frequency range, the time-temperature superposition principle is used. The shifting factor is calculated from the well-known William-Landel-Ferry formula. This allows for determination of damper parameters at any temperature based on the parameters obtained at the reference temperature. Laplace transformation of the derived equations of motion leads to the non-linear eigenproblem, which could be solved using the continuation method. The influence of temperature on the dynamic characteristics of the system i...
Seismic Isolation Systems Based on Friction-Fractional Viscoelastic Dampers
This work presents a study of some friction-viscoelastic damping systems for base isolation of structures. The systems are based on a friction-viscoelastic damping device made of a rotational friction damping device extended with a rotational fractional viscoelastic unit. The device is designed to dissipate seismic input energy and wind load and protect buildings from structural and non-structural damage during moderate and severe earthquakes as well as dynamic effects from wind. The damper device has been tested at DTU in Denmark, while intensive experimental tests have been carried out with the friction version of the damper at Takenaka research center in Japan. The comparison of results obtained from the experimental and numerical models show good agreement. Studying the response for static and dynamic loading has identified parameters influencing the response of a structure improved with a given damping system. The quality of the damping system is related to the structural response and an evaluation of the investigated damping systems is made. The damper device is easy to implement in structures. It is an economic device due to material availability. It can easily be replaced if damaged, which is unlikely to happen and it is easily readjusted in site. The frictional damper device has been installed in several buildings in Japan, Greece, India and Denmark.
Description of Dynamics Behaviour of Frame Structures with Fractional Viscoelastic Dampers
In this paper, frame structures with viscoelastic dampers mounted on them are considered. Viscoelastic (VE) dampers are modelled using two, three-parameter, fractional rheological models. The structures are treated as elastic linear systems. The equation of motion of the whole system (structure with dampers) is written in terms of state-space variables. The resulting matrix equation of motion is the fractional differential equation. Moreover, results of typical calculations are presented.
Comparative Study of Seismic Analysis of Structure with Viscoelastic Damper
2015
During an earthquake a large amount of energy is imparted into the structure. To reduce the response of structure undergoing vibrations it becomes important for the structure to absorb or dissipate the energy. Basically there are two methods to improve seismic protection of structures primarily traditional methods increasing stiffness of structures (i.e. shear wall, bracings, MR frames dual system) and secondary modern methods (i.e passive control systems, active control systems, semi active control systems and hybrid control system). Our focus is on passive control systems (Viscoelastic Damper). In passive energy dissipation systems the motion of structure is controlled by adding devices which modifies stiffness, damping or both. The present paper presents is the behavior of energy dissipation devices in addition to inherent structural damping of the R.C.C frame building. Damper considered namely Viscoelastic, is undertaken as additional damping members and analyzed by time history...
Frame structures with viscoelastic (VE) dampers mounted on them are considered in this paper. Generalized rheological models are used to model the VE dampers. The finite element method is used to derive the equations of motion of a structure with dampers and such equations are written in terms of both physical and state-space variables. A solution to motion equations in the frequency domain is provided and the dynamic properties of the structure with VE dampers are determined as a solution to the appropriately defined eigenvalue problem. The dynamic characteristics of a relatively large structure with VE are determined and discussed.
Evolutionary Model of Viscoelastic Dampers for Structural Applications
Journal of Engineering Mechanics, 1997
Th 7 effe~ts of tempe~ature on the energy dissipation of viscoelastic dampers for seismic mitigation of structures are mvestigated. To Simulate the damper behavior, an evolutionary model is proposed to describẽ e dependence o~~e~echanical propertie~of th~damper on the deformation frequency and the temperature mcre~e due to diSSipation. Thermorheologlcally Simple materials are considered and the influence of the de-formatio~frequency on the storage and loss moduli is modeled using fractional derivative operators. The effect of m~tenal temperature on the for~e-~eformation relation is modeled using the concept of evolutionary transfer func~0!1' and the proposed model IS Implemented using a step-by-step technique in the frequency domain. The p~edictions. of the proposed. model in the case of sinusoidal and seismic deformations show good agreement with e~penmental results. Fmally, the response spectra of single-degree-of-freedom structures with added vis-coelastic~pers and subjected to seismic excitation are computed using the proposed evolutionary model; the results obtained show that the thermal effect due to energy dissipation is not always negligible.