In this paper, a new scheme is presented for Controlling the structural vibrations, excited by the external dynamic effects such as the earthquake and etc. The proposed method is an active Control technique which is compatible with the structural dynamic behavior. In the other words, the proposed active Control method is formulated based on the structural dynamics theories. This approach could be used for designing a Control mechanism with multi actuators and multi sensors. For this purpose, the actuator’s forces vector is added to the dynamic equilibrium equations of the motion. The vector of the actuator’s forces is independent of the natural dynamic equilibrium equations of system and the elements of this vector are determined based on the active Control strategy. This paper presents an innovate concept to formulate the external Control forces which are applied to the main structure by the actuators. For calculating the Control forces, each actuator force is modeled as an equivalent viscous damper. If there is m actuator attached to the structure, m actuator force should be determined in the Control process. Based on the proposed technique, each actuator force is considered as a viscous force, added to the dynamic equations of motion. Therefore, there is m unknown force in the Control system. These m unknown parameters should be calculated at each instant time of the Control process which leads to reduce the structural vibration. For determining these m unknown actuator forces, m additional equations is required. Here, the critical damping concept of the structural dynamics theory is utilized to prepare the required equations. For this purpose, the actuator forces are determined so that several lower vibration modes are damped critically. In the other words, m actuator force is calculated if the m initial vibration’s modes are in the critical conditions. By creating critical damping condition for m initial vibration’s mode, a set of m simultaneous equations is achieved. In each time instance of the Control process, the m actuator forces are determined by solving this set of simultaneous equations. As a result, the proposed Control mechanism is formulated by a simple mathematical formulation. On the other hand, the proposed method does not depend on the type of the dynamic load and it could be applied to Control each structure with multi degrees of freedom. It should be noted that running these process in the case of multi actuator is the main originality of this paper. In the other words, a similar Control procedure is performed for a system with single actuator. For numerical verification of the proposed method, some criterions such as the maximum displacement are evaluated in a five-story shear building which is excited by the seismic load i.e. the Elcentro Earthquake. This study shows that the proposed active Control method has sufficient accuracy and suitable efficiency for decreasing the structural vibrations. According to the numerical results, the maximum drift in the upper floor of this five-story shear building is reduced by 55%. By increasing the number of actuators, the Control process with higher efficiency is achieved.

In recent years, semi-active Control has been introduced as a promising method for the seismic Control of structures, potentially combining the benefits of both passive and active Control systems. Magneto-rheological damper (MR) is one of the semi-active devices and its dynamic model is expressed by the Bouc-Wen model. The sliding sector Control (SSC) strategy as a robust Control approach is a class of variable structure (VS) systems for linear and nonlinear continuous-time systems with a special type of sliding sector using a new equivalent sector Control. The purpose of this study is to evaluate the effectiveness of the SSC strategy in determining the optimal voltage of MR at each step of time. For a numerical example, a three-story benchmark shear structure is considered subjected to normal (100%), high (150%), and low (50%) excitation levels of the El Centro earthquake. The results of the numerical simulations show that the semi-active Control system consisting of the SSC strategy and an MR damper can be beneficial in reducing the seismic responses of structures. Furthermore, the efficiency of the SSC strategy is also compared against that of the fuzzy and clipped-optimal Controllers. Comparative results of the numerical simulation confirm the robustness and ability of the SSC strategy.

Structural Control against earthquakes is becoming increasingly important. The linearquadratic optimal Control algorithm is proposed here to design active Control system for buildings against earthquake excitations. Full-state feedback system has been adopted. Active Tuned Mass Damper is used as the Control mechanism. The efficiency of the designed system has been verified against El-Centro earthquake. Active Control gives 35% more reduction in vibration of the structure than passive Control. Mass of the damper has appreciable effects on response parameters than its stiffness. A flexible damper proves to be more effective, but at the cost of actuating forces required. Performance of system is found to be optimum, when mass-damper is tuned to fundamental frequency of the structure. Stability of the structure is also enhanced by Active Control system. A SDOF building is presented to illustrate the study.

A common method for Controlling a group of parallel converters in decentralized Control strategy structure in an island microgrid, the use is the droop-down characteristics of frequency ω-P and voltage E-Q. However, the problem with using this method is that the reactive power is not properly distributed (in proportion to the capacity of the micronutrients) between the micronutrients, which may lead to overload in the converters. Microgrids may also suffer from dynamic stability problems such as power fluctuations, which can be increased by switching between active and reactive power Control. To avoid this problem, the X / R ratio of transmission lines is an important parameter that should be carefully considered in the design of micronutrient Controllers. By linearizing and simplifying conditions, the Control system conversion function model becomes a single input-single output system, which is efficient enough to show the relationship between Control parameters such as slope of droop characteristics and derivative sentences, virtual impedance, and voltage Controllers. Using this model, stability conditions for different parameters are analyzed. Also, to improve power distribution stability, common droop strategies are modified by adjusting the slope as well as adding nonlinear sentence sections. This approach reduces the coupling between active and reactive power Control and reduces the dependence of power distribution on grid parameters such as the X / R ratio. To evaluate the reliability of the proposed model, the simulation results in a sample island microgrid in MATLAB software are presented.

In this paper, a comparison is made between the predictive Control method and a neuro-fuzzy Control algorithm, which has been proposed recently by the authors, for Controlling a benchmark three-story frame structure subjected to earthquakes. Through numerical simulations, it is demonstrated that the proposed neuro-fuzzy Control algorithm can provide comparable and, in some cases, superior results.

Passive, active and hybrid vibration Control of structures during earthquakes were studied. Particular attention was given to hybrid preview Control strategy for protection of structures against earthquakes. A three-story building under fixed-base condition and with laminated rubber bearing base isolation system subject to the El Centro 1940 earthquake were analyzed. The cases that an active Control system with and without preview was present were studied in details. The corresponding structural responses with passive, active and hybrid vibration Control systems were evaluated. Accelerations and displacements responses for active systems with and without preview sensors for fixed-base and base-isolated structures were computed and the results were compared with those for the unprotected building. It was shown that properly designed passive, active and hybrid Control systems could effectively reduce the acceleration transmitted to structures during a major earthquake.It was also shown that the inclusion of the preview sensors in the active Control strategy improved the system performance considerably. The hybrid use of the laminated rubber bearing isolation system with the active Control strategies could provide significant improvement of the protection of buildings during seismic events.