Research On Seismic Semi-active Control For Large-scale Aqueducts

Aqueduct is a hydraulic structure which has played a very important role in South-to-North Water Transfer Project; it has very important significance for aqueduct seismic control. In this dissertation, the seismic responses analysis and semi-active control are studied for simple-support aqueduct which is applied widely in South-to-North Water Transfer Project. Using newly developed intelligent material Magneto rheological damper (MRD), the semi-active algorithm, the control positions, and the applicability of semi-active control for aqueduct are discussed. Two influencing factors of pounding effect and fluid-structural coupling effect are also studied during semi-active control phases. The primary work and achievements are as follows:1. The finite element model of aqueduct is established. Numerical simulations of the seismic responses of the large-scale aqueduct are performed within the MATLAB environment through a SIMULINK block. Respectively using traditional Newmark method and the SIMULINK method to calculate an example, the calculating results were compared. The results showed that, compared with traditional analysis method, the solution method based on the SIMULINK block is simple, precise, and facile, with intuitional and believable results.2. Numerical simulation of active control for large scale aqueduct under earthquake excitation is performed, control effects of several control schemes with different design parameters are compared, and the different positions of actuators set are carried on the discussion. Results indicate that, setting actuators can efficiently reduce the aqueduct seismic responses; however, only increase the number of actuators can not achieve equivalent performance.3. Based on the pounding phenomenon at expansion joints of large-scale aqueducts during earthquakes, an analytical model that considers the effects of collision is presented, with the time history analysis method of the determining the nonlinear seismic responses, the pounding effects of adjacent girders at expansion joints on seismic responses of large-scale aqueducts are studied, and the semi-active control of seismic responses of aqueduct under Earthquake excitation is performed with magneto rheological dampers. The result indicate that mitigation rate of semi-active control approaches with the active method, and semi-active devices using magneto rheological dampers are effective in reducing the pounding response when excited by seismic loading.4. Fluid-structure dynamic interaction can make the internal force of aqueduct. The dynamic analysis model of thin wall space aqueduct considering fluid-structure coupling is established. Semi-active control for aqueduct considering fluid-structure coupling is performed. Fluid-structure coupling does not have obvious bad influence on the effective damping rate of the aqueduct under semi-active control.5. The effect degree of seismic loading with different soil type and different amplitude, and the effect degree of different pier are studied. The results indicate that semi-active control can reduce the seismic responses of aqueduct with different pier under different ground motion input; the results from the present study may serve as a reference base for seismic design of large-scale aqueducts, and provide theoretical basis of aqueduct using semi-active devices.