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Paper Information

Journal:   MODARES CIVIL ENGINEERING JOURNAL   JUNE 2017 , Volume 17 , Number 2 ; Page(s) 21 To 32.
 
Paper: 

IMPROVEMENT IN SEISMIC CONTROL OF FRAME STRUCTURES AGAINST FAR-FAULT AND NEAR-FAULT EARTHQUAKES WITH NEW STRATEGY OF GAUSSIAN LINEAR OPTIMAL CONTROL

 
 
Author(s):  AMIN AFSHAR M.*
 
* CIVIL ENG. DEPT., FACULTY OF TECH. AND ENG., IMAM KHOMEINI INTERNATIONAL UNIVERSITY
 
Abstract: 

In this paper, a modified linear-quadratic-Gaussian (MLQG) optimal control algorithm is proposed for controlling the seismic response of the frame structures. Environmental loads (e.g., earthquakes) cannot be measured at the moment of calculation and exertion of the control forces to the structures. So these loads are not included in the conventional control algorithms, such as the linear quadratic regulator and the linear-quadratic-Gaussian control. Therefore the command of LQG optimal controller is merely a proportional feedback of the estimated state of the structure at the moment of exertion. This state approximation is performed by optimal state estimator or Kalman filter. In the proposed control algorithm, new variables are considered in the state space equation of the motion and also in both of Kalman Filter estimator and the optimal regulator. The new variables include control force and earthquake force, acceleration of the ground motion, which is non-measurable during the exertion of control force. This technique makes the controller be a combination of the control force in the last step and proportional feedback of the states in two last steps. According to the proposed control algorithm, two ways are selected. In the first, command control is the sum of the control force and ratios of the estimated state and measurement output of sensors, which are obtained and used in previous time step. The estimated state of system, used in the first command control, is calculated by the conventional and known Kalman Filter. In the second strategy of control, the Kalman Filter estimator is firstly modified based on new state space equations, and then the estimated state of structure is used for calculation of command control. Numerical simulation of a seven-storey structure with active control system under two far-fault earthquakes, including Northridge and Kobe, and two near-fault earthquakes, including El Centro and Hachinohe, are performed to show effectiveness of two proposed controls on mitigation of structural responses and compare to those of a uncontrolled structure and a structure controlled with conventional control. Also by sensitivity analysis, performance measures of controllers are investigated against changes of some controlling and perturbation parameters of systems or uncertainties. The performance measures include percentage reduction of the roof displacement of the controlled structure relative to that of the uncontrolled one, the root mean squares of normalized displacements, accelerations and control forces produced in controlled structure and total control energies exerted by all stories’ active devices under various controllers. The studied uncertainties are covariance of measurement noises and ambient loads. Increasing covariance of ambient loads as well as decreasing that of the measurement noise results in roof displacement reduction together with need to increase control energy. The analysis results demonstrate that performance of the proposed controllers, specially the second one, are better and also stable and robust under intensity and variations of uncertainties. So that the greatest reduction in maximum displacement (even up to 80 percent) compared to uncontrolled displacement of structure and meanwhile, very low energy consumption (about 10 percent of the maximum energy used by other controllers) are attained by the second proposed control strategy.

 
Keyword(s): LQG OPTIMAL CONTROL, KALMAN FILTER, ACTIVE STRUCTURAL CONTROL, STRUCTURAL DYNAMICS, EARTHQUAKE
 
 
References: 
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+ Click to Cite.
APA: Copy

AMIN AFSHAR, M. (2017). IMPROVEMENT IN SEISMIC CONTROL OF FRAME STRUCTURES AGAINST FAR-FAULT AND NEAR-FAULT EARTHQUAKES WITH NEW STRATEGY OF GAUSSIAN LINEAR OPTIMAL CONTROL. MODARES CIVIL ENGINEERING JOURNAL, 17(2 ), 21-32. https://www.sid.ir/en/journal/ViewPaper.aspx?id=570651



Vancouver: Copy

AMIN AFSHAR M.. IMPROVEMENT IN SEISMIC CONTROL OF FRAME STRUCTURES AGAINST FAR-FAULT AND NEAR-FAULT EARTHQUAKES WITH NEW STRATEGY OF GAUSSIAN LINEAR OPTIMAL CONTROL. MODARES CIVIL ENGINEERING JOURNAL. 2017 [cited 2021May18];17(2 ):21-32. Available from: https://www.sid.ir/en/journal/ViewPaper.aspx?id=570651



IEEE: Copy

AMIN AFSHAR, M., 2017. IMPROVEMENT IN SEISMIC CONTROL OF FRAME STRUCTURES AGAINST FAR-FAULT AND NEAR-FAULT EARTHQUAKES WITH NEW STRATEGY OF GAUSSIAN LINEAR OPTIMAL CONTROL. MODARES CIVIL ENGINEERING JOURNAL, [online] 17(2 ), pp.21-32. Available: https://www.sid.ir/en/journal/ViewPaper.aspx?id=570651.



 
 
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