Proposal of an equivalent linearization method to predict seismic hysteretic energy demand considering stiffness degradation effects

2020 ◽  
Vol 29 (9) ◽  
Author(s):  
Maryam Samimifar ◽  
Ali Massumi ◽  
Abdolreza S. Moghadam
Keyword(s):  
Energy Demand ◽  
Linearization Method ◽  
Stiffness Degradation ◽  
Equivalent Linearization ◽  
Hysteretic Energy ◽  
Equivalent Linearization Method

Estimation of Seismic Damage Induced by Near- and Far-Fault Earthquakes Using Modified Equivalent Linearization Method of Mid-Rise RC Buildings

2020 ◽  
Vol 20 (13) ◽  
pp. 2041017
Author(s):  
Chien-Kuo Chiu ◽  
Lorddy Z. Nugroho ◽  
Wen-I. Liao
Keyword(s):  
Energy Dissipation ◽  
Damage Index ◽  
Linearization Method ◽  
Equivalent Linearization ◽  
Hysteretic Energy ◽  
Maximum Deformation ◽  
Deformation Response ◽  
Rc Building ◽  
Equivalent Linearization Method ◽  
Far Fault

For the seismic design of a mid-rise reinforced concrete (RC) building considering the damage control, the main purpose of this work is to propose a simplified method that can be used to estimate the damage index or damage state induced by the near-fault and far-fault earthquakes. In addition to the maximum deformation response, the hysteretic energy dissipation induced the earthquakes is also considered in the damage index quantification based on the modified equivalent linearization method (MELM). Based on the damage index model in terms of the maximum deformation response and hysteretic energy dissipation under an earthquake, this work provides a convenient method by which an engineer can determine the damage-controlling minimal ductility requirement to ensure that the damage index remains under a specified value. For a mid-rise RC building structure, an engineer can also apply the simplified formula proposed in this work to obtain the damage-controlling yielding strength for a specified ductility capacity.

Equivalent Linearization of Bladed Disk Assemblies with Friction Nonlinearities Under Random Excitation

2020 ◽  
Author(s):  
Alwin Förster ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek
Keyword(s):  
Degrees Of Freedom ◽  
Turbine Blades ◽  
Random Excitation ◽  
Linearization Method ◽  
Equivalent Linearization ◽  
Friction Damper ◽  
Bladed Disk ◽  
Stationary Stochastic Processes ◽  
Bladed Disk Assembly ◽  
Equivalent Linearization Method

Abstract The present article addresses the vibrational behaviour of bladed disk assemblies with nonlinear shroud coupling under random excitation. In order to increase the service life and safety of turbine blades, intense calculations are carried out to predict the vibrational behaviour. The use of friction dampers for energy dissipation and suppression of large amplitudes makes the mechanical system nonlinear, which complicates the calculations. Depending on the stage, different types of excitation can occur in a turbine, from clearly defined deterministic to random excitation. So far, the latter problem has only been dealt with to a limited extent in the literature on turbomachinery. Nevertheless, there are in general different approaches and methods to address this problem most of which are strongly restricted with regard to the number of degrees of freedom. The focus of this paper is the application of an equivalent linearization method to calculate the stochastic response of an academic model of a bladed disk assembly under random excitation. The nonlinear contact is modelled both with an elastic Coulomb-slider and a Bouc-Wen formulation to reproduce the hysteretic character of a friction nonlinearity occurring in the presence of a friction damper. Both the excitation and the response are limited to mean-free, stationary stochastic processes, which means that the stochastic moments, do not change over time. Unlike previous papers on this topic, the calculations are performed on a full bladed disk assembly in which each segment is approximated with several degrees of freedom.

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