Analysis of controllers in suppressing the structural building vibration

Two degree of freedom (2 DOF) mass spring damper system is used in representing as building structure that dealing with the earthquake vibration. The real analytical input is used to the system that taken at El Centro earthquake that occurred in May 1940 with magnitude of 7.1 Mw. Two types of controller are presented in controlling the vibration which are fuzzy logic (FL) and sliding mode controller (SMC). The paper was aimed to improve the performance of building structure towards vibration based on proposed controllers. Fuzzy logic and sliding mode controller are widely known with robustness character. The mathematical model of two degree of freedom mass spring damper wasis derived to obtain the relationship between mass, spring, damper, force and actuator. Fuzzy logic and sliding mode controllers were implemented to 2 DOF system to suppress the earthquake vibration of two storeys building. Matlab/Simulink was used in designing the system and controllers to present the result of two storeys displacement time response and input control voltage for uncontrolled and controlled system. Then the data of earthquake disturbance was taken based on real seismic occurred at El Centro to make it as the force disturbance input to the building structure system. The controllers proposed would minimize the vibration that used in sample earthquake disturbance data. The simulation result was carried out by using Matlab/Simulink. The simulation result showed sliding mode controller was better controller than fuzzy logic. In specific, by using the controller, earthquake vibration can be reduced

Numerical modelling of multiple tuned mass damper equipped with magneto rheological damper for attenuation of building seismic responses

TMD is basically designed to be tuned to the dominant frequency of a structure which the excitation frequency will resonate the structural motion out of phase to reduce unwanted vibration. However, a single unit TMD is only capable of suppressing the fundamental structural mode and for multimode control, more than one TMD is needed. In this study, a 3-storey benchmark reinforced structural building subjected to El Centro seismic ground motion is modelled as uncontrolled Primary Structure (PS) by including properties such as stiffness and damping. For the case of controlled PS which the passive mechanism is included to the system, optimum parameters of both TMD and Multiple TMD (MTMD) are designed to be tuned to the dedicated structural modes where the performance is dependent on parameters such as mass ratio, optimum damping ratio, and optimum frequency ratio. The input and output components of structural system arrangements are then characterized in the transfer function manner and then converted into state space function. For enhancement of the passive system, Magneto-Rheological (MR) damper is added to both single TMD and MTMD passive system. The response analysis is executed using both time history and frequency response analysis. From the analysis, semi-active case is the most effective mechanism with 99% displacement reduction for the third and second floors, and 98% for the first floor, compared to the uncontrolled case. It is concluded that the MR damper significantly contributed to the enhancement of the passive system to mitigate structural seismic vibration

Design of distributed multi-actuator systems with incomplete state information for vibration control of large structures

In this paper, we investigate the design and performance of static feedback controllers with partial-state information for the seismic protection of tall buildings equipped with incomplete multi-actuation systems. The proposed approach considers a partially instrumented multi-story building with an incomplete system of interstory force–actuation devices implemented on selected levels of the building, and an associated set of collocated sensors that measure the corresponding interstory drifts and interstory velocities. The main elements of the proposed controller design methodology are presented by means of a twenty-story building equipped with a system of ten interstory actuators arranged in three different layouts: concentrated, semi-distributed and fully-distributed. For these control configurations, partial-state controllers are designed following a static output-feedback H-infinity controller design approach, and the corresponding frequency and time responses are investigated. The obtained results clearly indicate that the proposed partial-state controllers are effective in mitigating the building seismic response. They also show that a suitable distribution of the instrumented stories is a relevant factor in the control system performance.Peer ReviewedPostprint (published version

A smart mechatronic base isolation system using earthquake early warning

Earthquake is one of the most devastating natural disasters. In the last few decades, many seismic mitigation techniques have been developed. They include passive, semi-active and active control which have been proven their effectiveness in events of earthquakes. Among them, base isolation has been regarded as a mature technology and commercialisation is common in earthquake-prone countries. This technology decouples the main structure from its foundation and effectively lengthens the natural period of vibration, away from resonance vibration. However, the lateral stiffness of base isolation devices is generally too low to resist serviceability lateral forces such as wind and flood which may cause unacceptable lateral movements of the structure. Added lateral stiffness and/or damping is usually required. On the other hand, the Earthquake Early Warning (EEW) system which uses different arrival time of seismic P and S waves is readily available in Japan, Taiwan, parts of China and Europe. This technology offers more possibilities for improvement of earthquake mitigation technique. This project develops a smart mechatronic base isolation system which can be triggered by the EEW system. It uses the earthquake early warning signals and nearby monitoring signals to determine the situation and automatically switches to the appropriate anti-seismic mode. In the first phase of research, a one-dimensional system is developed and tested on an electrical shake table. A prototype smart mechatronic base isolation system is developed. In this prototype design, electromagnetic shear keys which lock the base isolator are released either by simulated EEW signals or on-site accelerometers. The advantage of this design gives the main structure a very strong stiffness under in-service condition (i.e. when there is no ground motion) while maximizing the effectiveness of base isolation when ground motion is anticipated. The system is fully automated, and the main structure is re-entered once ground motion ceases. In the second stage, a two-dimensional base isolation, created by low-friction linear bearings is developed and activation of base isolation is carried out by linear actuators. In the third stage, the system is developed further. Light Detection and Ranging (LIDAR) sensors are added to monitor position of base isolator in real-time, an active control strategy is added into the microcontroller and actuation is carried out by stepper motors. Using the feedbacks provided by the sensor the active base-isolation system re-position the main structure in real-time. The research presented in this thesis opens up new opportunities in future seismic risk mitigation of civil structures. By connecting the EEWS and mechatronic devices, the performance of traditional base isolation system can be enhanced