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This paper presents the problem definition and guidelines of a set of benchmark control problems for seismically excited nonlinear buildings. Focusing on three typical steel structures, 3-, 9-and 20-story buildings designed for the SAC project for the Los Angeles, California region, the goal of this study is to provide a clear basis to evaluate the efficacy of various structural control strategies. A nonlinear evaluation model has been developed that portrays the salient features of the structural system. Evaluation criteria and control constraints are presented for the design problems. The task of each participant in this benchmark study is to define (including sensors and control algorithms), evaluate and report on their proposed control strategies. These strategies may be either passive, active, semi-active or a combination thereof. The benchmark control problems will then facilitate direct comparison of the relative merits of the various control strategies. To illustrate some of the design challenges, a sample control strategy employing active control with a linear quadratic Gaussian (LQG) control algorithm is applied to the 20-story structure.

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SUMMARYIn a companion paper (Spencer et al.), an overview and problem definition was presented for a well-defined benchmark structural control problem for a model building configured with an Active Mass Driver (AMD). A second benchmark problem is posed here based on a high-fidelity analytical model of a three-storey, tendon-controlled structure at the National Center for Earthquake Engineering Research (NCEER). The purpose of formulating this problem is to provide another setting in which to evaluate the relative effectiveness and implementability of various structural control algorithms. To achieve a high level of realism, an evaluation model is presented in the problem definition which is derived directly from experimental data obtained for the structure. This model accurately represents the behaviour of the laboratory structure and fully incorporates actuator/sensor dynamics. As in the companion paper, the evaluation model will be considered as the real structural system. In general, controllers that are successfully implemented on the evaluation model can be expected to perform similarly in the laboratory setting. Several evaluation criteria are given, along with the associated control design constraints.1998 John Wiley & Sons, Ltd.KEY WORDS: structural control; benchmark problem; earthquake; active tendon control EXPERIMENTAL STRUCTUREThe structure on which the evaluation model is based is the actively controlled, three-storey, single-bay, model building considered in Chung et al. The test structure, shown in Figures 1 and 2, has a mass of 2950 kg, distributed among the three floors, and is 254 cm in height. The ratio of model quantities to those corresponding to the prototype structure are: force"1 : 16, mass"1 : 16, time"1 : 2, displacement"1 : 4 and acceleration"1 : 1. Due to the time scaling, the natural frequencies of the model are approximately twice those of the prototype. The first three modes of the model system are at 2)27, 7)33, and 12)24 Hz, with associated damping ratios given, respectively, by 0)6, 0)7, and 0)3 per cent. A hydraulic control actuator, four pretensioned tendons, and a stiff steel frame connecting the actuator to the tendons are provided to apply control forces to the test structure. The four diagonal tendons transmit the force from the control actuator to the first floor of the structure, and the steel frame connects the actuator to the tendons. Because hydraulic actuators are inherently open-loop unstable, a feedback control system is

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In this technical note, the development of a framework for multi-site distributed simulations is presented, The aigotithm is suitable for any combination of physical (laboratory) and analytical (computer) distributed simulations of structures, their foundat ions and the underlying substrata subjected to static and dynamic loading. Two examples of multi-site testing and multi-platform simulation are given, The main contribution in this note is the separation between time-step integration and stiffness formulation, which enables the use of static analysis and testing as modules of the main control module referred to as the simulation coordinator. The approach proposed is intuitive, simple and efficient. It is therefore recommended for use in distributed analysis using different programs, distributed testing facilities (e.g. the NEES equipment sites) or a combination of analysis and testing.