Benchmark Control Problems for Seismically Excited Nonlinear Buildings

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, 9and 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. Introduction The protection of civil structures, including material content and human occupants, is, without doubt, a world-wide priority. The extent of protection may range from reliable operation and occupant comfort to human and structural survivability. Civil structures, including existing and future buildings, towers and bridges, must be adequately protected from a variety of events, including earthquakes, winds, waves and traffic. The protection of structures is now moving from reliance entirely on the inelastic deformation of the structure to dissipate the energy of severe dynamic loadings, to the application of passive, active and semi-active structural control devices to mitigate undesired responses to dynamic loads. However, even in controlled structures, it can be expected that large seismic events, such as the 1994 Northridge and the 1995 Kobe earthquakes, will cause structural members to exceed the elastic limit. 1. On leave from the Central Research Institute of Electric Power Industry of Japan.