This study investigates reducing the vibration of structures under different earthquakes using magnetorheological dampers. To investigate the effect of the magnetorheological damper arrangement on reducing the vibration amplitude of structures, experimental studies are conducted in which magnetorheological dampers are commanded by a robust controller. So, the performance of the system is investigated using different combinations of two magnetorheological dampers on a building and three different arrangements for dampers are considered for experimental study. Additionally, an H_∞ controller is designed to determine the voltage transmitted to the magnetorheological dampers. The results show that the magnetorheological damper commanded with the robust controller effectively reduces the vibration of a six-story steel structure. Furthermore, the magnetorheological damper arrangement in which the one end is connected to the ground reduces the vibration amplitudes.

This paper investigated the performance of a semi-active tuned mass damper (STMD) on a multi-degree of freedom (MDOF) building model. A magnetorheological (MR) damper was used as a control element that provided semi-activity in the STMD. The Hardware in the Loop Simulation (HILS) method was applied to mitigate the difficulty and expense of experimental studies, as well as to obtain more realistic results from numerical simulations. In the implementation of this method for the STMD, the MR damper was set up experimentally, other parts of the system were modeled as computer simulations, and studies were carried out by operating these two parts simultaneously. System performance was investigated by excitation with two different acceleration inputs produced from the natural frequencies of the MDOF building. Additionally, a robust ${\mathrm{H}}_{\infty }$ controller was designed to determine the voltage transmitted to the MR damper. The results showed that the HILS method could be applied successfully to STMDs used in structural systems, and robust ${\mathrm{H}}_{\infty }$ controls improve system responses with semi-active control applications. Moreover, the control performance of the MR damper develops with an increase in the mass of the STMD.

In this study, the effects of cracks in the columns of a single degree of freedom (SDOF) steel structure model on the system responses due to the decrease in the equivalent spring coefficient were investigated. The crack in the columns was modeled as an edge crack, and the crack was thought to behave like a spring. The crack is considered as the mode I crack type (opening mode) specified in linear fracture mechanics. In order to examine the responses of the system under the influence of different excitations, the changes in displacement, acceleration, and power spectral density responses under the influence of harmonic excitation at a frequency equal to the fundamental frequency of the SDOF model and six different earthquake excitations were examined.

This paper aims to investigate the performances of a semi-active tuned mass damper (STMD) used to reduce the vibrations of buildings under different seismic excitation by the real-time hybrid simulation (RTHS) method. In the STMD, the MR damper is used as a control element with a variable damping feature. The RTHS method is an alternative to experimentally studying the STMD system. MR damper is critically significant for the system and is experimentally installed. At the same time, the other parts are designed in numerical simulation and tested simultaneously. MR damper is a control element whose damping value can change according to the amount of voltage transmitted. Therefore, the groundhook control method determines the MR damper voltage variations. The results show that the control method applied to MR damper-controlled STMD effectively suppresses structural vibrations.

In this study, a PI-PD controller was designed via weighted geometric center method (WGC) for a quarter vehicle model to suppress the vertical vibrations. The proposed design is based on finding the weighted geometric center of the area formed by the control parameters that make the system stable. The WGC method has two main stages. First, an area formed by the parameters of the PD controller (kf, kd) in the inner loop is obtained and the weighted geometric center of this area is calculated. Then, using these obtained parameters, the inner loop is reduced to a single block, and the parameters of the PI controller in the external loop (kp, ki) are calculated using the stability boundary curve as in the first step, and the weighted geometric center is calculated. The simulation results show that the PI-PD controller designed with the weighted geometric center method offers successful responses for the time delay quarter vehicle system.

Bu çalışmada, Ayarlı Kütle Sönümleyicilerinin (AKS) yapısal sistem üzerinde etkileri parametre değişimi ve farklı katlara yerleşimleri dikkate alınarak incelenmiştir. Çok serbestlik dereceli çelik konstrüksiyon bir bina modelinin için tasarlanan AKS, bu bina modelinin her bir katına ayrı ayrı eklenerek sistem cevapları incelenmiştir. Her bir kat için ayrı bir simülasyon yapılmıştır. Ayrıca, kat yerleşimlerinin yanında değişiminin etkilerini incelemek amacıyla, AKS’nin farklı kütle, rijitlik ve sönüm parametreleri kullanılmıştır. Sistem cevapları farklı depremler etkisinde analiz edilmiştir. AKS parametrelerinin belirlenmesinde farklı yaklaşımlardan faydalanılmıştır. Sonuçlar, AKS’nin yerleşimi ile parametre değişimlerinin sistem performansını etkilediği, ve üst katlara doğru AKS yerleşimi ile yüksek kütle oranlarının, sistem cevaplarını daha etkili bir şekilde bastırdığını göstermiştir.