Vibration Control Of Tall Buildings Under Earthquake And Strong Wind Excitation

In recent years, structures of civil engineering usually fail during large seismic events and strong winds, often resulting in loss of human life and property damage. Tens of thousands of people have died and billions of dollars in property damage have been lost as a result of earthquakes and strong winds. The application of structural control is one of effective methods in safeguarding civil structures against failure under external excitations. The methods for vibration control of tall buildings under earthquake and strong wind excitation are researched in this dissertation. The main contents are as follows:1. Differencing mostly researchers focused on the studies of linear response control of civil engineering structures, semi-active control strategies for reducing nonlinear response of high-rise buildings are mainly researched in this dissertation.2. The definition of a benchmark control problem for seismically excited nonlinear high-rise buildings is presented. Besides the seventeen evaluation criteria specified in the benchmark problem, two additional criteria to describe the performance of the controlled system are considered. The first newly proposed evaluation criteria, designed P₁, is a nondimensionalized measure of the maximum permanent interstory drift ratio. The second newly proposed evaluation criteria, designed P₂, is a nondimensionalized measure of the total permanent interstory drift ratio over the height of the structure. All nineteen criteria are to be evaluated for the specified earthquakes at various magnitudes.3. The semi-active strategy of H_∞ control algorithm is creatively proposed to reduce nonlinear response of the benchmark building. The relatively accuracy reduced-order building model which is used for designing the controller is obtained by the suggested Guyan-State reduction. Based on the measured vector of floor accelerations and semi-active control forces, a Kalman-Bucy observer of semi-active strategy is built to obtain the estimation of the state vector. A semi-active controller of H_∞ algorithm based on MR dampers is developed, in which the uncertainty effects of earthquake excitation is taken into account. Numerical simulation is carried out for analyzing the nonlinear seismic responses of the controlled 20-story benchmarkbuilding, and the simulation results are compared to those of the LQG control systems. The analysis results show that the developed semi-active strategy has good performance in reducing the nonlinear seismic response of high-rise building and minimize the damages in the building structures caused by strong earthquakes.4. The semi-active strategy of model predictive control algorithm is creatively proposed to suppress nonlinear response of the benchmark building. Firstly, a multi-step predictive model is built to estimate the seismic dynamics of high-rise building, in which the effects of some complicated factors, such as the nonlinear, time-varying, model mismatching, disturbances and uncertainty of controlled system, are taken into account by the prediction error feedback. The prediction error is that the actual system output is compared to the model prediction at each time step. The time delay in the control loop is also taken into account in the multi-step predictive model. Then, based on the predictive model, a Kalman-Bucy observer is proposed to obtain the estimation of the state vector. A semi-active model predictive control strategy based on magnetorheological dampers is developed. Finally, numerical simulation is carried out for analyzing the nonlinear seismic responses of the controlled 20-story benchmark building, and the simulation results were compared to those of the LQG control systems. The analysis results show that the developed semi-active strategy can reduce the nonlinear seismic response of high-rise building efficiently. The semi-active model predictive control is based on the discrete time system and is appropriate for real-time control implementation.5. The definition of a benchmark problem for the response control of wind-induced tall buildings is presented. The control strategy using fuzzy neural network is creatively proposed to reduce across wind response of the benchmark building. Based on the measured vector of floor accelerations and control forces of the controlled system, a fuzzy neural network controller is designed, in which few sensors and no observer are needed. With traditional control methods, such as LQG control, an observer should be designed to determine the structure vibration state, and lots of sensors are needed to guarantee the precision of observer. The fuzzy neural network controller to predict control action eliminates the effects of time delay in the control loop. With a fuzzy logic control strategy, it's difficult to obtain an appropriate set of rules and membership functions, and with a neural network control strategy, it's also difficult to obtain the numbers of network layer and hidden layer node, the meaning of weight, network structure. But it's easy to solve these problems utilizing the ability of adaptive learning of the fuzzy neural network controller. Numerical simulation is carried out for analyzing wind-induced responses of the benchmark building, and thesimulation results are compared to those of the LQG control systems. The analysis results show that the control strategy using fuzzy neural network has good performance in reducing across wind response of the benchmark building.