PurposeDesign and improvement of control algorithms considering the existing limitations have been always one of important challenges in the field of control of structures.Materials and methodsIn the present study, active control of structures with active tendon and Linear Quadratic Regulator (LQR) algorithm, which is a common control algorithm in engineering applications, is investigated. In this regard, considering uncertainties in the parameters and noise in the sensors, the control parameters of LQR algorithm are updated continuously using fuzzy observer to achieve the highest decrease in the structural response, in addition to fulfilling limitations of the actuator. In fact, fuzzy logic as a smart device that can deal with nonlinearity and indeterminacy of the system, improves performance of the LQR controller and reduces structural responses by online changing the weight matrix, R. To evaluate the proposed method, two multi-story structures with 3 and 6 stories are analyzed under 4 ground motion records.ConclusionThe attained result shows a robust and stable behavior of the control algorithm that resulted in a very effective performance of LQR control in the presence of parametric uncertainties and sensor's noises.