AbstractThis paper presents hybrid control systems for seismic protection of a phase II benchmark 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 system is acting alone. In this study, two types of hybrid control system are considered to protect the cable‐stayed bridge under seismic events. Lead–rubber bearings are used as passive control devices to reduce the earthquake‐induced forces in the bridge and hydraulic actuators or magnetorheological fluid dampers are used as additional control devices to further reduce the bridge responses, especially deck displacements. Numerical simulation results show that the performances of the proposed hybrid control systems are superior to those of the passive control system, and slightly better than those of the active or semi‐active control system alone. Furthermore, it is verified that the hybrid control systems are robust to mass or stiffness parameter perturbation, and there is no sign of instability in the overall system due to the passive control part. Therefore, the proposed hybrid control systems could effectively be applied to seismically excited cable‐stayed bridges. Copyright © 2003 John Wiley & Sons, Ltd.

AbstractThis paper describes the Benchmark Problem for controlled cable‐stayed bridges. The benchmark in question is the first to be related directly to bridges. It follows on from past experience and experimentation, devoted to buildings, developed at an international level. These past experiences focused upon buildings subjected to wind and earthquake excitation. In this paper seismic excitation is explored in relation to bridges.Three different schemes of active control are compared with each other. Their performance is also compared with the two most widely used passive control systems which summarize present energy dissipation practice. Copyright © 2003 John Wiley & Sons, Ltd.

AbstractTwo H2‐based control strategies are proposed and their applications to civil engineering benchmark structures are presented. The first strategy deals with a class of excitations with a specified ‘energy’ bound, referred to as the H2‐based controller with energy‐bounded excitations (H2B‐EB), whereas the second strategy addresses a class of excitations with a specified peak bound, referred to as the H2‐based controller with peak‐bounded excitations (H2B‐PB). Both control strategies are derived by minimizing an upper bound of the H2 performance with the constraints (or penalties) on the peak values of another set of quantities, such as the control resources. State feedback and dynamic output feedback controllers are derived and presented. The design syntheses of these control strategies are developed and formulated within the framework of linear matrix inequalities (LMIs), so that the LMI toolbox in MATLAB can be used effectively and conveniently. These control strategies are applied to the Phase I long‐span cable‐stayed benchmark bridge subject to earthquakes and a wind‐excited 76‐storey benchmark building to illustrate their applicability to practical problems. Simulation results indicate that the performances of these proposed controllers for structural responses are better than that of the LQG sample controller. It is shown that these new control strategies are viable and effective for applications to civil engineering structures. Copyright © 2003 John Wiley & Sons, Ltd.

AbstractThe effectiveness of a variable damper employing pseudo‐negative stiffness control on benchmark cable‐stayed bridges was studied. Combination of a pseudo‐negative stiffness hysteretic loop produced by the variable damper plus elastic stiffness of the deck‐tower connections produces a hysteretic loop that approaches rigid perfectly plastic force–deformation characteristics with a large damping ratio. The advantage is that sensors are required only at damper connections to measure relative displacements. Moreover, the small amount of sensors and simple algorithm reduce the source of errors and uncertainties. Comparisons are made between passive, pseudo‐negative stiffness, and active control for the phase II benchmark bridge. The results of pseudo‐negative stiffness control are significantly better than those of passive control and comparable to those of active control. Copyright © 2003 John Wiley & Sons, Ltd.

AbstractThis paper presents the problem definition for the second generation of benchmark structural control problems for cable‐stayed bridges. The goal of this study is to provide a testbed for the development of strategies for the control of cable stayed‐bridges. Based on detailed drawings of the Bill Emerson Memorial Bridge, a three‐dimensional evaluation model has been developed to represent the complex behavior of the full‐scale benchmark bridge. Phase II considers more complex structural behavior than phase I, including multi‐support and transverse excitations. Evaluation criteria are presented for the design problem that are consistent with the goals of seismic response control of a cable‐stayed bridge. Control constraints are also provided to ensure that the benchmark results are representative of a control implementation on the physical structure. Each participant in this benchmark bridge control study is given the task of defining, evaluating and reporting on their proposed control strategies. Participants should also evaluate the robust stability and performance of their resulting designs through simulation with an evaluation model which includes additional mass due to snow loads. The problem and a sample control design have been made available in the form of a set of MATLAB equations. Copyright © 2003 John Wiley & Sons, Ltd.

AbstractThis paper reviews the subject of structural damage detection from the point of view of instrumentation. The focus is on the measurement and interpretation of structural variables such as vibration, displacement and curvature. Some major approaches in the area of civil engineering and aeronautics are presented. Especially the corresponding sensor and data collection solutions are discussed as well as the key technologies for relating variations in the measured parameters to damage. Copyright © 2003 John Wiley & Sons, Ltd.

AbstractA major contribution to the status of vibration monitoring has been delivered by the European Brite EuRam research project BE‐3157, System Identification to Monitor Civil Engineering Structures (SIMCES). This paper gives a brief description of the project, the tests performed on bridge Z24 and the results obtained from these tests. The need for further research is indicated. Copyright © 2003 John Wiley & Sons, Ltd.

AbstractThis study investigates the application of a semi‐active control method utilizing a magnetorheological (MR) damper to reduce the response of an isolated structure subjected to earthquake excitations. A series of performance tests were carried out on a 2 kN MR damper and the Bouc–Wen model was utilized to establish the numerical model of the MR device. A fuzzy logic control algorithm was then applied to establish the controller. Results of numerical simulation indicated that the established control algorithm is useful to reduce displacement and acceleration responses of base‐isolated structures. Copyright © 2003 John Wiley & Sons, Ltd.