Semi-active Structural Control Systems Research Articles

Shaking table testing of a steel frame structure equipped with semi-active MR dampers: comparison of control algorithms

The effectiveness of the various control algorithms for semi-active structural control systems proposed in the literature is highly questionable when dealing with earthquake actions, which never reach a steady state. From this perspective, the paper summarizes the results of an experimental activity aimed to compare the effectiveness of four different semi-active control algorithms on a structural mock up representative of a class of structural systems particularly prone to seismic actions. The controlled structure is a near full scale 2-story steel frame, equipped with two semi-active bracing systems including two magnetorheological dampers designed and manufactured in Europe. A set of earthquake records has been applied at the base of the structure, by utilizing a shaking table facility. Experimental results are compared in terms of displacements, absolute accelerations and energy dissipation capability. A further analysis on the percentage incidence of undesired and/or unpredictable operations corresponding to each algorithm gives an insight on some factors affecting the reliability and, in turn, the real effectiveness of semi-active structural control systems.

A model for signal processing and predictive control of semi-active structural control system

The theory for structural control has been well developed and applied to perform excellent energy dissipation using dampers. Both active and semi-active control systems may be used to decide on the optimal switch point of the damper based on the current and past structural responses to the excitation of external forces. However, numerous noises may occur when the control signals are accessed and transported thus causing a delay of the damper. Therefore, a predictive control technique that integrates an improved method of detecting the control signal based on the direction of the structural motion, and a calculator for detecting the velocity using the least-square polynomial regression is proposed in this research. Comparisons of the analytical data and experimental results show that this predictor is effective in switching the moving direction of the semi-active damper. This conclusion is further verified using the component and shaking table test with constant amplitude but various frequencies, and the El Centro earthquake test. All tests confirm that this predictive control technique is effective to alleviate the time delay problem of semi-active dampers. This predictive control technique promotes about 30% to 40% reduction of the structural displacement response and about 35% to 45% reduction of the structural acceleration response.

Future directions in structural control

This paper will be confined to the application of active, hybrid, and semi-active structural control systems. Based on what have been accomplished over the last 30 years, an assessment is presented concerning Outlook of structural control technology and pressing issues that must be addressed in order to further advance the concept of structural control as a cornerstone in modern structural engineering. Several research areas deserving further exploration and development are identified. The paper will focus oil one of these areas, namely, integrated design of control/structural systems

Passive Control Reinforced Concrete Frame Mechanism with High Strength Reinforcements and Its Potential Benefits Against Earthquakes

Severe earthquakes continue to cause major catastrophes. Many devices in active, hybrid, and semi-active structural control systems which are used as controllable force devices are costly to build and maintain. The passive control reinforced concrete frame (PCRCF) reinforced with high strength steel only in the columns presented here provides structural systems more resistance to lateral earthquake loadings at comparatively lower cost. The effectiveness is demonstrated by a nonlinear static analysis using fiber model for a single story single bay frame. The study shows that the use of high performance steel in columns prevents formation of plastic hinges at the critical column base sections and failures are always initiated by reinforcement yielding at the beam ends. Furthermore, after experiencing severe lateral drift, the passive control design has small residual displacements compared to ordinary reinforced concrete frames. PCRCF rehabilitation and strengthening can be achieved more easily as compared with ordinary reinforced concrete frame.

Reliability of Applied Semiactive Structural Control System

Research on semiactive control of structures has been carried out actively since the middle of the 1990s. After a theoretical and experimental study, a semiactive structural control system has been applied to an actual five-story building in 1998 by use of a continuous-variable semiactive hydraulic damper that has a maximum damping force of 1,000 kN. For application of the system, health monitoring, fail-safe operation, possibility of power failure, sensor malfunction, control device operation, computer, and communication system, etc., need to be considered. In this paper, reliability of an operational semiactive structural control system is discussed from the view points of health monitoring of the system and fail-safe functions. Power failures, abnormal outputs of sensors, valve damages, and communication errors, are focused as main problems. Dynamic load and forced vibration tests were carried out to determine fail-safe functions. After completion of the system installation, monitoring for earthquake excitation was initiated. Results presented show the effectiveness of functioning of the system. Finally, reliability of the system is confirmed and satisfactory performance is demonstrated.

Statistical performance analysis of seismic‐excited structures with active interaction control

AbstractThis paper presents a statistical performance analysis of a semi‐active structural control system for suppressing the vibration response of building structures during strong seismic events. The proposed semi‐active mass damper device consists of a high‐frequency mass damper with large stiffness, and an actively controlled interaction element that connects the mass damper to the structure. Through actively modulating the operating states of the interaction elements according to pre‐specified control logic, vibrational energy in the structure is dissipated in the mass damper device and the vibration of the structure is thus suppressed. The control logic, categorized under active interaction control, is defined directly in physical space by minimizing the inter‐storey drift of the structure to the maximum extent. This semi‐active structural control approach has been shown to be effective in reducing the vibration response of building structures due to specific earthquake ground motions. To further evaluate the control performance, a Monte Carlo simulation of the seismic response of a three‐storey steel‐framed building model equipped with the proposed semi‐active mass damper device is performed based on a large ensemble of artificially generated earthquake ground motions. A procedure for generating code‐compatible artificial earthquake accelerograms is also briefly described. The results obtained clearly demonstrate the effectiveness of the proposed semi‐active mass damper device in controlling vibrations of building structures during large earthquakes. Copyright © 2003 John Wiley & Sons, Ltd.

Preface to ‘Practical applications of active and semi‐active structural control systems to actual civil engineering structures’

Earthquake Engineering & Structural DynamicsVolume 30, Issue 11 p. 1563-1563 Preface Preface to ‘Practical applications of active and semi-active structural control systems to actual civil engineering structures’ Takuji Kobori, Takuji Kobori Professor Emeritus of Kyoto University, and Past President of the International Association for Structural ControlSearch for more papers by this author Takuji Kobori, Takuji Kobori Professor Emeritus of Kyoto University, and Past President of the International Association for Structural ControlSearch for more papers by this author First published: 05 July 2001 https://doi.org/10.1002/eqe.80Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume30, Issue11Special Issue: Practical Applications of Active and Semi-active Structural Control Systems to Actual Civil Engineering StructuresNovember 2001Pages 1563-1563 RelatedInformation

Stability of a Lyapunov Controller for a Semi-active Structural Control System with Nonlinear Actuator Dynamics

We investigate semi-active control for a wide class of systems with scalar nonlinear semi-active actuator dynamics and consider the problem of designing control laws that guarantee stability and provide sufficient performance. Requiring the semi-active actuator to satisfy two general conditions, we present a method for designing quickest descent controllers generated from quadratic Lyapunov functions that guarantee asymptotic stability within the operating range of the semiactive device for the zero disturbance case. For the external excitation case, bounded-input, bounded-output stability is achieved and a stable attractor (ball of ultimate boundedness) of the system is computed based on the upper bound of the disturbances. We show that our wide class of systems covers, in particular, two nonlinear actuator models from the literature. Tuning the performance of the simple Lyapunov controllers is straightforward using either modal or state penalties. Simulation results are presented which indicate that the Lyapunov control laws can be selected to provide similar decay rates as a “time-optimal” controller for a semi-actively controlled single degree of freedom structure with no external excitation.

Forced vibration test of a building with semi-active damper system

The authors developed a semi-active hydraulic damper (SHD) and installed it in an actual building in 1998. This was the first application of a semi-active structural control system that can control a building's response in a large earthquake by continuously changing the device's damping coefficient. A forced vibration test was carried out by an exciter with a maximum force of 100 kN to investigate the building's vibration characteristics and to determine the system's performance. As a result, the primary resonance frequency and the damping ratio of a building that the SHDs were not jointed to, decreased as the exciting force increased due to the influence of non-linear members such as PC curtain walls. The equivalent damping ratio was estimated by approximating the resonance curves using the steady-state response of the SDOF bilinear hysteretic system. After the eight SHDs were jointed to the building, the system's performance was identified by a response control test for steady-state vibration. The elements that composed the semi-active damper system demonstrated the specified performance and the whole system operated well. Copyright © 2000 John Wiley & Sons, Ltd.

Semi-active control systems for seismic protection of structures: a state-of-the-art review

As passive structural control systems begin to see an increased acceptance within the earthquake engineering community, strong research efforts have been shifted towards the development of semi-active structural control systems. To place semi-active control systems within a proper frame of reference, this paper begins with a qualitative description and comparison of passive, active, and semi-active control systems for protecting structures subjected to earthquake induced ground motion. A detailed literature review of semi-active control systems is then provided which provides references to both theoretical and experimental research but concentrates on describing the results of experimental work. Specifically, the review focuses on descriptions of the dynamic behavior and distinguishing features of various systems which have been experimentally tested both at the component level and within small-scale structural models. The semi-active systems which are reviewed include stiffness control devices, electrorheological dampers, magnetorheological dampers, friction control devices, fluid viscous dampers, tuned mass dampers and tuned liquid dampers. The review clearly demonstrates that semi-active control devices have the potential for improving the seismic behavior of full-scale civil structures.