Optimized and Decentralized Pulse Control of Seismically Excited Steel Structures

Fereidoun Amini,Maryam Hassanali,Majd Javanbakht 한국강구조학회 2017 International Journal of Steel Structures Vol.17 No.2

The idea of decomposing a centralized complicated system into several synchronous decentralized subsystems has been resulted into the development of decentralized control methods. In this study, a decentralized pulse control scheme is presented based on the theory of Inclusion Principle for steel systems comprising a multi-overlapping structure. The proposed control algorithm is basically an active control system that generates corrective pulses at each moment when the displacement or acceleration exceeds the predefined threshold. In order to evaluate the performance of proposed control system, a numerical study is conducted. The control system is implemented for two linear structural models of five- and twenty-story steel buildings. An optimization algorithm (PSO) is also used to determine the locations of required control inputs in the 20-story building. The results show that the proposed algorithm can substantially mitigate the structural response under different earthquake records (for 5-story model) and different subsystem configurations (for 20-story model).

Adaptive control of rotationally non-linear asymmetric structures under seismic loads

Amini, Fereidoun,Rezazadeh, Hassan,Afshar, Majid Amin Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6

This paper aims to inspect the effectiveness of the Simple Adaptive Control Method (SACM) to control the response of asymmetric buildings with rotationally non-linear behavior under seismic loads. SACM is a direct control method and was previously used to improve the performance of linear and non-linear structures. In most of these studies, the modeled structures were two-dimensional shear buildings. In reality, the building plans might be asymmetric, which cause the buildings to experience torsional motions under earthquake excitation. In this study, SACM is used to improve the performance of asymmetric buildings, and unlike conventional linear models, the non-linear inertial coupling terms are considered in the equations of motion. SACM performance is compared with the Linear Quadratic Regulator (LQR) algorithm. Moreover, the LQR algorithm is modified, so that it is appropriate for rotationally non-linear buildings. Active tuned mass dampers are used to improve the performance of the modeled buildings. The results show that SACM is successful in reducing the response of asymmetric buildings with rotationally non-linear behavior under earthquake excitation. Furthermore, the results of the SACM were very close to those of the LQR algorithm.

Adaptive control of rotationally non-linear asymmetric structures under seismic loads

Fereidoun Amini,Hassan Rezazadeh,Majid Amin Afshar 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.65 No.6

This paper aims to inspect the effectiveness of the Simple Adaptive Control Method (SACM) to control the response of asymmetric buildings with rotationally non-linear behavior under seismic loads. SACM is a direct control method and was previously used to improve the performance of linear and non-linear structures. In most of these studies, the modeled structures were two-dimensional shear buildings. In reality, the building plans might be asymmetric, which cause the buildings to experience torsional motions under earthquake excitation. In this study, SACM is used to improve the performance of asymmetric buildings, and unlike conventional linear models, the non-linear inertial coupling terms are considered in the equations of motion. SACM performance is compared with the Linear Quadratic Regulator (LQR) algorithm. Moreover, the LQR algorithm is modified, so that it is appropriate for rotationally non-linear buildings. Active tuned mass dampers are used to improve the performance of the modeled buildings. The results show that SACM is successful in reducing the response of asymmetric buildings with rotationally non-linear behavior under earthquake excitation. Furthermore, the results of the SACM were very close to those of the LQR algorithm.

Capacity design by developed pole placement structural control

Fereidoun Amini,Kaveh Karami 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.1

To ensure safety and long term performance, structural control has rapidly matured over the past decade into a viable means of limiting structural responses to strong winds and earthquakes. Nonlinear response history analysis requires rigorous procedure to compute seismic demands. Therefore the simplified nonlinear analysis procedures are useful to determine performance of the structure. In this investigation, application of improved capacity demand diagram method in the control of structural system is presented for the first time. Developed pole assignment method (DPAM) in structural systems control is introduced. Genetic algorithm (GA) is employed as an optimization tool for minimizing a target function that defines values of coefficient matrices providing the placement of actuators and optimal control forces. The ground acceleration is modified under induced control forces. Due to this, performance of structure based on improved nonlinear demand diagram is selected to threshold of nonlinear behavior of structure. With small energy consumption characteristics, semi-active devices are especially attractive solutions for limiting earthquake effects. To illustrate the efficiency of DPAM, a 30-story steel moment frame structure employing the semi-active control devices is applied. In comparison to the widely used linear quadratic regulation (LQR), the DPAM controller was shown to be just as effective and better in the reduction of structural responses during large earthquakes.

Capacity design by developed pole placement structural control

Amini, Fereidoun,Karami, Kaveh Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.39 No.1

To ensure safety and long term performance, structural control has rapidly matured over the past decade into a viable means of limiting structural responses to strong winds and earthquakes. Nonlinear response history analysis requires rigorous procedure to compute seismic demands. Therefore the simplified nonlinear analysis procedures are useful to determine performance of the structure. In this investigation, application of improved capacity demand diagram method in the control of structural system is presented for the first time. Developed pole assignment method (DPAM) in structural systems control is introduced. Genetic algorithm (GA) is employed as an optimization tool for minimizing a target function that defines values of coefficient matrices providing the placement of actuators and optimal control forces. The ground acceleration is modified under induced control forces. Due to this, performance of structure based on improved nonlinear demand diagram is selected to threshold of nonlinear behavior of structure. With small energy consumption characteristics, semi-active devices are especially attractive solutions for limiting earthquake effects. To illustrate the efficiency of DPAM, a 30-story steel moment frame structure employing the semi-active control devices is applied. In comparison to the widely used linear quadratic regulation (LQR), the DPAM controller was shown to be just as effective and better in the reduction of structural responses during large earthquakes.

Online structural identification by Teager Energy Operator and blind source separation

Vida Ghasemi,Fereidoun Amini 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.2

This paper deals with an application of adaptive blind source separation (BSS) method, equivariant adaptive separation via independence (EASI), and Teager Energy Operator (TEO) for online identification of structural modal parameters. The aim of adaptive BSS methods is recovering a set of independent sources from their unknown linear mixtures in each step when a new sample is received. In the proposed approach, firstly, the EASI method is used to decompose structural responses into independent sources at each instance. Secondly, the TEO based demodulation method with discrete energy separation algorithm (DESA-1) is applied to each independent source, and the instantaneous frequencies and damping ratios are extracted. The DESA-1 method can provide the fast time response and has high resolution so it is suitable for online problems. This paper also compares the performance of DESA-1 algorithm with Hilbert transform (HT) method. Compared to HT method, the DESA-1 method requires smaller amounts of samples to estimate and has a smaller computational complexity and faster adaption due to instantaneous characteristic. Furthermore, due to high resolution of the DESA-1 algorithm, it is very sensitive to noise and outliers. The effectiveness of the proposed approach has been validated using synthetic examples and a benchmark structure.

Application of simple adaptive control to an MR damper-based control system for seismically excited nonlinear buildings

Majd Javanbakht,Fereidoun Amini 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.6

In this paper, Simple Adaptive Control (SAC) is used to enhance the seismic response of nonlinear tall buildings based on acceleration feedback. Semi-active MR dampers are employed as control actuator due to their reliability and well-known dynamic models. Acceleration feedback is used because of availability, cost-efficiency and reliable measurements of acceleration sensors. However, using acceleration feedback in the control loop causes the structure not to apparently meet some requirements of the SAC algorithm. In addition to defining an appropriate SAC reference model and using inherently stable MR dampers, a modification in the original structure of the SAC is proposed in order to improve its adaptability to the situation in which the plant does not satisfy the algorithm\' s stability requirements. To investigate the performance of the developed control system, a numerical study is conducted on the benchmark 20-story nonlinear building and the responses of the SAC-controlled structure are compared to an H2/LQG clipped-optimal controller under the effect of different seismic excitations. As indicated by the results, SAC controller effectively reduces the story drifts and hence the seismically-induced damage throughout the structural members despite its simplicity, independence of structural parameters and while using fewer number of dampers in contrast with the H2/LQG clipped-optimal controller.

Optimal Control of Steel Structures by Improved Particle Swarm

Saeid Aghajanian,Hadi Baghi,Fereidoun Amini,Masoud Zabihi Samani 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.2

Active control is one of the modern approaches in seismic design of steel structures. Recently, induced by economicconsiderations, especially high expenses of control systems, optimality has become an important issue. In this paper an activesystem is used to control a steel structure’s displacements by a simplified pole assignment method. To optimize the number,the locations, and the total driving force of the required actuators, an improved particle swarm algorithm is presented focusingon the parameters of the velocity equation. A Geographical neighborhood topology and an adaptive inertia weight are used toimprove the standard PSO algorithm. In addition to the local and global best solutions, the positions of the best particles inthe geographical neighborhood are mathematically represented in an additional term. The performance of the proposedalgorithm is compared with the traditional Genetic Algorithm (GA) and the standard particle swarm considering the optimalcontrol of a 12-story steel structure as a numerical example. High capabilities of the proposed method in terms of the controltarget, convergence rate, and accuracy are simultaneously clarified by the results.

Developing a smart structure using integrated DDA/ISMP and semi-active variable stiffness device

Kaveh Karami,Satish Nagarajaiah,Fereidoun Amini 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.18 No.5

Recent studies integrating vibration control and structural health monitoring (SHM) use control devices and control algorithms to enable system identification and damage detection. In this study real-time SHM is used to enhance structural vibration control and reduce damage. A newly proposed control algorithm, including integrated real-time SHM and semi-active control strategy, is presented to mitigate both damage and seismic response of the main structure under strong seismic ground motion. The semi-active independently variable stiffness (SAIVS) device is used as semi-active control device in this investigation. The proper stiffness of SAIVS device is obtained using a new developed semi-active control algorithm based on real-time damage tracking of structure by damage detection algorithm based on identified system Markov parameters (DDA/ISMP) method. A three bay five story steel braced frame structure, which is equipped with one SAIVS device at each story, is employed to illustrate the efficiency of the proposed algorithm. The obtained results show that the proposed control algorithm could significantly decrease damage in most parts of the structure. Also, the dynamic response of the structure is effectively reduced by using the proposed control algorithm during four strong earthquakes. In comparison to passive on and off cases, the results demonstrate that the performance of the proposed control algorithm in decreasing both damage and dynamic responses of structure is significantly enhanced than the passive cases. Furthermore, from the energy consumption point of view the maximum and the cumulative control force in the proposed control algorithm is less than the passive-on case, considerably.