Hybrid control systems for seismic protection of a phase II benchmark cable‐stayed bridge

This paper presents an integrated passive-active (i.e. hybrid) system for seismic response control of a cable-stayed bridge. Since multiple control devices are operating, a hybrid control system could alleviate some of the restrictions and limitations that exist when each system is acting alone. Lead rubber bearings are used as passive control devices to reduce the earthquake-induced forces in the bridge and hydraulic actuators are used as active control devices to further reduce the bridge responses, especially deck displacements. In the proposed hybrid control system, a linear quadratic Gaussian control algorithm is adopted as a primary controller. In addition, a secondary bang-bang type (i.e. on-off type) controller according to the responses of lead rubber bearings is considered to increase the controller robustness. Numerical simulation results show that control performances of the integrated passive-active control system are superior to those of the passive control system and are slightly better than those of the fully active control system. Furthermore, it is verified that the hybrid control system with a bang-bang type controller is more robust for stiffness perturbation than the active controller with a μ-synthesis method, and there are no signs of instability in the over-all system whereas the active control system with linear quadratic Gaussian algorithm shows instabilities in the perturbed system. Therefore, the proposed hybrid protective system could effectively be used for seismically excited cable-stayed bridges.

This paper presents a robust hybrid isolation system for seismic response control of a cable-stayed bridge. Because multiple control devices are operating, a hybrid control system could alleviate some of the restrictions and limitations that exist when each control system, such as passive, active, semiactive control system, is acting alone. However, the overall system robustness may be negatively impacted by active control part of the hybrid system or active controller may cause instability due to smalt margins. Therefore, control algorithms that guarantee the controller robustness should be considered to improve the overall system robustness of the hybrid seismic isolation system and to enhance the possibility of real applications of the system consequently. In this study, a hybrid isolation system combining lead rubber bearings and hydraulic actuators is used for seismic response control of a cable-stayed bridge. Lead rubber bearings are used as passive control devices to reduce the earthquake-induced forces in the bridge and hydraulic actuators are used as active control.devices to further reduce the bridge responses, especially deck displacements. Furthermore, two kinds of robust control algorithms, i.e., the Ha and Hoo control designs with frequency weighting filters, are used to improve the controller robustness of the overall system. The numerical simulation results show that the proposed hybrid seismic isolation systems have the excellent robustnes for stiffness perturbations without loss of control performances under the considered earthquakes in this study. Therefore, the proposed robust hybrid isolation systems could effectively be used to seismically excited cabbstayed bridges.

Hybrid control strategy for seismic protection of a benchmark cable-stayed bridge

This paper presents a hybrid control strategy for seismic protection of a benchmark cable-stayed bridge, which is provided as a testbed structure for the development of strategies for the control of cable-stayed bridges. This benchmark problem considers the cable-stayed bridge that is scheduled for completion in Cape Girardeau, Missouri, USA in 2003. Seismic considerations were strongly considered in the design of this bridge due to the location of the bridge in the New Madrid seismic zone and its critical role as a principal crossing of the Mississippi river. Based on detailed drawings of this cable-stayed bridge, a three-dimensional linearlized evaluation model has been developed to represent the complex behavior of the bridge. A set of eighteen evaluation criteria has been developed to evaluate the capabilities of each control strategy. In this study, a hybrid control system is composed of a passive control system to reduce the earthquake-induced forces in the structure and an active control system to further reduce the bridge responses, especially deck displacements. Conventional base isolation devices such as lead rubber bearings are used for the passive control design and Bouc-Wen model is used to simulate the nonlinear behavior of these devices For the active control design, ideal hydraulic actuators are used and on /LQG control algorithm is adopted. Numerical simulation results show that the performance of the proposed hybrid control strategy is quite effective compared to that of the passive control strategy and slightly better than that of the active control strategy. The hybrid control method is also more reliable than the fully active control method due to the passive control part. Therefore, the proposed hybrid control strategy can effectively be used to seismically excited cable-stayed bridges.

Controlling naturally ventilated double-skin façade to reduce energy consumption in buildings

Earthquake response of benchmark cable-stayed bridge with passive hybrid control systems is investigated. The passive hybrid system consists of high damping rubber bearing, lead-rubber bearing, friction pendulum system and resilient-friction base isolator (R-FBI) supplemented with the linear and non-linear viscous fluid damper (VFD). Considering the phase-I benchmark problem, the ground acceleration is only applied in the longitudinal direction acting simultaneously at all supports. The seismic response of benchmark bridge is obtained by solving the governing equations of motion by Newmark's step-by-step integration method. A comparative performance study among the four hybrid control systems for seismic response control of bridge is carried out by finding the various evaluation criteria under different parameters of the hybrid control system. Significant reductions in the base shear, overturning moment and other responses (especially deck displacements) were observed by using the passive hybrid control s...

Present paper investigates the application of Magnetorheological (MR) damper for a seismic control of the horizontally curved bridge isolated with different passive devices. The main aim of the study is to investigate the effectiveness of hybrid system for the seismic control of curved bridge with variation of important parameters. The selected bridge is a three span continuous concrete box girder supported on pier and rigid abutment. The bridge deck is model as a single spine beam, which is made with number of small straight two node beam elements and supporting pier model as linear lumped mass system. The MR dampers are located between the deck and abutments or piers in chord and radial direction. The bridge is excited with four different ground motions having different ground motion characteristics with all three-ground motion components (horizontal as well as vertical). The analysis results confirm use of MR damper with different isolator effective in controlling the response of the curved bridge and MR damper also effective in controlling the bearing displacement. The combination of MR and Lead rubber bearing (LRB) can provide an effective way for overall seismic control of curved bridge structure.

본 연구에서는 수동, 능동, 반능동 및 복합 시스템과 같은 다양한 제어시스템의 효율성을 미국토목학회에서 제시한 지진하중을 받는 첫번째 벤치 마크 사장교을 이용해 조사하였다. 이 벤치마크 문제는 2003년 완공 예정으로 미국 Mississippi주에 건설중인 Bill Emerson Memorial교를 대상 구조물로 고려하였다. Bill Emerson Memorial 교는 New Madrid 지진구역에 위치하고 Wississippi 강을 횡단하는 주요 교량이라는 점 때문에 설계 단계에서부터 내진설계가 고려되었다. 사장교의 상세한 설계도면에 기초해 교량의 복잡한 거동을 나타낼 수 있는 3차원 선형모델과 각 제어시스템의 성능을 평가하기 위한 18개의 평가기준이 개발되었다. 본 연구에서는 네 종류의 수동제어 시스템, 한 종류의 능동제어 시스템, 두 종류의 반능동제어 시스템 밑 세 종류의 복합제어 시스템이 고려되었다. 수치해석 결과 모든 제어시스템은 지진하중을 받는 벤치마크 사장교의 응답을 감소시켰다. 그러나, 수동제어 시스템의 경우에는 뛰어난 제어성능을 얻기 위해서 다른 제어시스템에 비해 커다란 제어력을 필요로했다. 강인성에 관한 수지해석 결과에 따르면, 수동, 반능동 및 복합제어 시스템이 구조물 강성의 불확실성에 대해 강인함을 보였다. 따라서, 반능동 및 복합제어 시스템이 토목구조물과 같은 대형구조물의 실제 적용에 보다 적절하다. This paper preliminarily investigates the effectiveness of various control systems, such as passive, active, semiactive and hybrid control, for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. This benchm.0.00000ark problem considers the cable-stayed bridge that is scheduled for completion in Missouri, USA In 2003. Seismic considerations were strongly considered in the design of this bridge due to location of the bridge and its critical role as a principal crossing of the Mississippi River. Based on detailed drawings of this cable-stayed bridge, a three-dimensional linearized evaluation model has been developed to represent the complex behavior of the bridge. A set of eighteen evaluation criteria has been developed to evaluate the capability of each control system. In this study, four passive control systems, one active control system, two semiactive control systems and three hybrid control systems are considered. Numerical simulation results show that all the control systems are effective in reducing the responses of the benchmark cable-stayed bridge under the historical earthquakes. To get good performance, however, the passive control systems need quite large control forces compared to other control systems. The simulation results also demonstrate that the passive, semiactive and hybrid control systems are robust to the stiffness uncertainty of the structure. Therefore, the semiactive and hybrid control systems are more appropriate in real applications for full-scale civil infrastructures.

The catastrophic damages of past earthquakes show that irregular structures are more vulnerable to seismic excitation. On the other hand, dynamic responses depend on the severity of irregularity which is hard to be determined precisely. In this study, performance and reliability of magnetorheological (MR) fluid dampers in controlling torsional-lateral responses of irregular structures are evaluated. In this regard, plan-asymmetry is studied by considering mass eccentricity; whereas vertical-irregularity is investigated by creating mass difference in adjacent stories of the structure. The performance of MR dampers in seismic control of the structure is then evaluated for passive and semi-active control scenarios. The reliability of the structure-MR damper system is then studied by considering uncertainties in severity of irregularities using the Monte Carlo simulation method. Six types of limit state function are defined and the reliability of the system for controlling the desired responses are derived. The results show satisfactory performance of MR dampers in controlling coupled torsional-lateral responses of the structure in which semi-active control system outperforms the passive control system. The results also confirm that the performance of the control system highly depends on the structure irregularity which should be taken into account for design of a safe and reliable structure.

The dynamic performance of base isolation systems provides an effective means to reduce the seismic vulnerability of buildings. However, large displacements in the base isolation during seismic events pose a major challenge for this control system. Recently, novel control systems have been implemented to control and reduce the excessive displacements. This study presents an evaluation of the seismic performance of unconnected‐fiber‐reinforced elastomeric isolators (U‐FREI) and variable orifice damper (VOD) devices used together as a hybrid control system for a low‐degree‐of‐freedom reference structure by employing real‐time hybrid simulation (RTHS) testing technique. This physical cybernetic testing methodology allows a dynamic system of interest to be substructured into two components: numerical and experimental. In this study, the numerical substructure corresponds to a 2‐degree of freedom model, representing a reference structure, and an experimental substructure was formed using the hybrid control system described. To develop an interface between the two substructures, a horizontal transfer system (HTS) was implemented and coupled with a vertical transfer system (VTS). Using RTHS, the performance of the reference structure and the hybrid control system was evaluated under six seismic events: CAM, CAT, El Centro, Loma Prieta, Pizarro, and Chihuahua, at a maximum acceleration of 0.10 g (0.981 m·s−2). The experimental behavior of the hybrid control system allows the reference structure to reduce its maximum drift by more than 24% compared to the fixed structure. Finally, the performance and accuracy of the RTHS tests were calculated.

Semiactive control systems have received considerable attention for protecting structures against natural hazards such as strong earthquakes and high winds, because they not only offer the reliability of passive control systems but also maintain the versatility and adaptability of fully active control systems. Among the many semiactive control devices, magnetorheological (MR) fluid dampers comprise one particularly promising class. In the field of civil engineering, much research and development on MR fluid damper-based control systems has been conducted since this unique semiactive device was first introduced to civil engineering applications in mid 1990s. In 2001, MR fluid dampers were applied to the full-scale in-service civil engineering structures for the first time. This state-of-the-art paper includes a detailed literature review of dynamic models of MR fluid dampers for describing their complex dynamic behavior and control algorithms considering the characteristics of MR fluid dampers. This extensive review provides references to semiactive control systems using MR fluid dampers. The MR fluid damper-based semiactive control systems are shown to have the potential for mitigating the responses of full-scale civil engineering structures under natural hazards.

Vibration characteristics analysis of shaft system for bulb hydroelectric generating unit based on magnetorheological fluid damper

Due to limitations on the use of passive base isolation systems which show poor performance in near field seismic excitations or active systems which require high external power, as stand alone control devices for a range of seismic excitations, a hybrid control system that mitigates the limitations of either passive or active control systems is preferred. The present study examines the use of semi–active base isolation systems for vibration mitigation. A combination of base isolation and MR-dampers forms the control device that has been deployed as a base isolation unit in the building. A combination of GA–fuzzy based control algorithm has been proposed to be implemented as a control strategy. Scaled seismic inputs for both near and far field excitations have been used in this study on three story (base + three) building. The paper presents the analytical modeling and results obtained through numerical experiments.

Control-structure interaction (CSI) during structural vibration control system has been investigated in some current literatures. However, the interaction between MR damper and flexible stay cable has not been reported. In this paper, experimental investigation on vibration control is carried out on a stay cable model incorporated with one small size magneto-rheological (MR) fluid damper taking into account the interaction effect of the stay cable and the MR damper. Experiments on the vibration control of the stay cable model attached with the MR damper with different constant current input indicates the obvious interaction between the stay cable and the MR damper. A novel model of MR damper with constant current input coupled with stay cable is proposed to better predict the MR damper’s behavior considering the interaction effect between the stay cable and the MR damper. The proposed coupling model is validated by the numerical simulations using the experimental results.

Structural vibration control using active or passive control strategy is a viable technology for enhancing structural functionality and safety against natural hazards such as strong earthquakes and high wind gusts. Both the active and passive control systems have their limitations. The passive control system has limited capability to control the structural response whereas the active control system depends on external power. The power requirement for active control of civil engineering structures is usually quite high. Thus, a hybrid control system is a viable solution to alleviate some of the limitations. In this paper a multi‐objective optimal design of a hybrid control system for seismically excited building structures has been proposed. A tuned mass damper (TMD) and an active mass driver (AMD) have been used as the passive and active control components of the hybrid control system, respectively. A fuzzy logic controller (FLC) has been used to drive the AMD as the FLC has inherent robustness and ability to handle the non‐linearities and uncertainties. The genetic algorithm has been used for the optimization of the control system. Peak acceleration and displacement responses non‐dimensionalized with respect to the uncontrolled peak acceleration and displacement responses, respectively, have been used as the two objectives of the multi‐objective optimization problem. The proposed design approach for an optimum hybrid mass damper (HMD) system, driven by FLC has been demonstrated with the help of a numerical example. It is shown that the optimum values of the design parameters of the hybrid control system can be determined without specifying the modes to be controlled. The proposed FLC driven HMD has been found to be very effective for vibration control of seismically excited buildings in comparison with the available results for the same example structure but with a different optimal absorber. Copyright © 2002 John Wiley & Sons, Ltd.