Seismic response reduction of building structures using a semi-active control system based on a brain emotional learning controller

The present paper investigates the effectiveness of a bio-inspired semi-active controller to reduce seismic-induced vibrations in building structures. The control system is based on the use of a MR damper in combination with the so-called Brain emotional learning based intelligent controller (BELBIC), which is an intelligent controller based on the model of Limbic system of brain. A general case for a three degrees of freedom building structure excited by the El Centro earthquake will be used to demonstrate how a semi-active control system comprising a MR damper in a non-collocated configuration can reduce the structural response under seismic loading. Hence, the key objective of this study will be to evaluate and verify the efficiency of a MR damper in controlling the level of vibrations in a three degrees of freedom building structure by means of a BEL controller. A comparison between uncontrolled and controlled structural responses are used to validate the performance and efficiency of the proposed semi-active controller.info:eu-repo/semantics/publishedVersio

Optimal control of a plan asymmetric structure using magnetorheological dampers

Although building structures can be perceived as a combination of primary frames in two orthogonal directions, they are three-dimensional systems that usually present a very complex dynamic behavior due to irregular geometric configurations, in particular due to plant stiffness or mass eccentricities. This asymmetric geometry results in coupled lateral–torsional motion produced by wind and seismic loading with consequences in the design of lateral and corner columns. A considerable amount of research effort has been devoted to develop structural control systems to reduce the effects of plan asymmetries and to improve the dynamic behavior of these buildings. This paper presents a numerical analysis of a semi-active control system with MR dampers designed to reduce lateral–torsional responses of a plan asymmetric building structure excited by El Centro NS earthquake ground motion. A parametric study comprising passive and semi-active control modes is given to demonstrate the effectiveness of the proposed control system with respect to uncontrolled case. The numerical results prove the efficiency of the semi-active control system and its potential use in mitigating coupled lateral–torsional structural responses.info:eu-repo/semantics/publishedVersio

Properties and numerical modeling of MR dampers

Among the different strategies available to control engineering vibrations, the semi-active contrai based on Magnetorheological (MR) dampers have become a promising technology to be used in civil engineering structures. The ability of these devices to change the stmctairal behavior without the need of large power sources is a major advantage that can be used to justify their potential application to this engineering branch. This paper reviews the basic concept of MR fluids and provides an insight of MR dampers dynamic behavior and the available numerical procedures to describe the damper response. In the first section an overview ofthe basic properties ofthe MR fluids and the fluid behavior under different flow regimes are presented. Then, a selection of numerical models to simulate MR dampers behavior will be presented based on the available literature

Neuro-fuzzy modeling of a sponge-type MR damper

Numerical modeling of MR dampers based on parametric models constitutes one of the main methodologies to simulate the behavior of this type of devices. However, its highly non-linear nature and also its inherent rheological behavior make this type of numerical modeling harsh and complicated, which hinders the development of simple models capable to cover all aspects associated with the proper numerical simulation of the damper behavior and therefore usually complex parametric models involving several parameters are required to achieve a reliable and accurate representation of its rheological behavior. Hence, non-parametric models represent another feasible approach to simulate the complex non-linear behavior of MR dampers although in this case allowing to obtain a wide-ranging numerical model without the need to define or identify a large number of model parameters. In this context, we attempt to model and predict the response of a sponge-type MR damper using a non-parametric modeling technique based on an Adaptive Neuro-Fuzzy Inference System (ANFIS) model. Initially, the basic structure of this data modeling technique is presented and the main aspects regarding the development of a neuro-fuzzy model for MR dampers are addressed. Then, an ANFIS modeling technique is developed to obtain a non-parametric model for the MR damper. Finally, a comparison between the numerical and experimental results will be presented to validate the selected modeling technique.info:eu-repo/semantics/publishedVersio

Passive control of civil engineering structures

Structural control has been a major research area i n aerospace engineering aimed at solving very complex problems related with analysis and des ign of flexible structures. The efficiency of these strategies to improve the performance of s everal structural systems suggests its potential to reduce damage and control earthquake4i nduced response in civil structures. Therefore, this technology has been well accepted b y structural engineers as a feasible approach to design improved earthquake resistant st ructures. The present paper provide a brief description of each control scheme describing the m ain properties of different anti4seismic solutions and presenting the most relevant developm ents in this area. Control methodologies and devices are highlighted identifying their advan tages and limitations. The main focus of this paper is to present a comprehensive state4of4t he4art of passive control system. Different passive techniques are described and the effectiven ess in mitigating seismic hazard for structures is addressed.The authors gratefully acknowledge the funding by Ministério da Ciência, Tecnologia e Ensino Superior, FCT, Portugal, under grant SFRH/BD/49094/2008

Estudo preliminar sobre o desempenho sísmico de pórticos metálicos contraventados a partir de análises estáticas não-lineares (PUSHOVER)

Neste artigo apresenta-se uma investigação preliminar sobre o uso de métodos de análise pushover no dimensionamento de pórticos com elementos de contraventamento (diagonais metálicas). Para este efeito foram analisados três pórticos metálicos de aço com 3, 6 e 10 pisos. Os pórticos foram modelados através do programa de elementos finitos MIDAS/Civil e nas análises foram usados métodos não-lineares estáticos de pushover. O objectivo principal consiste na avaliação comparativa dos desempenhos estruturais, e portanto também na consequente conveniência do uso deste método “pushover” na análise sísmica de estruturas

A survey of semi-active control with MR dampers

The present work describes part of the R&D on using a semi-active structural control technique in a civ il engineering experimental model frame equipped with a MR damper, developed within COVICOCEPAD project approved in the framework of Eurocores prog ram S3T. Some results are provided associated with the calibration of a magneto-rheological (MR) damper at FEUP (Faculdade de Engenharia da Universidade do Porto) as well as on the experiment al modal identification of the dynamic properties o f a small-scale metallic frame, with and without the in clusion of a specific MR device. Some numerical results of the controlled frame under simulated ear thquakes are given, to be later compared with the experimental results of such frame installed in a Q uanser shaking table.This work is integrated in the thematic and activities of the international collaborative research project COVICOCEPAD approved by the European Science Foundation (ESF) within the Smart Structural Systems Technologies (S3T) Program. It was sponsored in Portugal until last December 2010 by FCT (Fundação para a Ciência e a Tecnologia) project PPPCDT-05-S3T-FP054-COVICOCEPAD, fact that is herein acknowledged

Semi-active vibration control of buildings using MR dampers: numerical and experimental verification

The present work describes part of the R&D on using a semi-active structural control technique in a civil engineering experimental model frame equipped with a MR damper, developed within COVICOCEPAD project approved in the framework of Eurocores program S3T. Some results are provided associated with the calibration of a MR damper at FEUP as well as on the experimental modal identification of the dynamic properties of a small-scale metallic frame, without and with inclusion of a specific MR device. Some numerical results of the controlled frame under simulated earthquakes are given, to be later compared with the experimental results of such frame installed in a Quanser shaking table

A parametric study of the non-linear geometric behaviour and carrying capacity of 3D asymmetric steel frames

Non-linear P-delta behaviour of three-dimensional frames with plan and elevation asymmetries is studied, using a parametric variation of geometry in plan and a stiffness variation along the height. Some behavioural aspects of a calibration frame have been addressed to ascertain the importance of the nodal rigidity, modelled with laminar elements of the type shell with implicit formulation of thick plate or modelled with elastic stiff springs, in the study and modelling of the geometric nonlinearity and stability of such calibration frame. Eurocode 3 criteria for second order analyses is briefly addressed in connection with the 2D frame classification with respect to sway behaviour; however for 3D structures the calculated carrying capacity is independent of this classification. So a parametric study of the critical load factor of asymmetric three-dimensional frames, un-braced and braced, permits to characterize their carrying capacity with respect to overall structural stability

Non-linear carrying capacity of asymmetric three-dimensional braced steel frames

Non-linear P-delta behaviour of three-dimensional frames with irregular plant geometry is studied, using a parametric variation of geometry and stiffness formerly chosen, by comparing results obtained with author’s developed software and with established commercial software. Using the exact total stiffness formulation of nonlinear geometric analyses in the developed software, allows surveying its degree of precision in selected calibration examples, as compared to the exact analytical results as well as to commercial software results. A parametric study of the critical load factor of asymmetric three-dimensional frames, un-braced and braced, permits to characterize their carrying capacity with respect to overall structural stability