【作者】 林伟；

【导师】 李忠献； 丁阳； 倪一清；

【作者基本信息】 天津大学 ， 结构工程， 2009， 博士

【摘要】 近年来,我国已经建成了许多规模宏大的大跨度空间建筑。由于自由度庞大、空间受力复杂等特点,大跨度空间结构的抗震安全性越来越受到工程界和学术界的高度关注。磁流变(MR)阻尼器是一种新型半主动控制装置,在土木工程结构的振动控制中得到了广泛的应用研究,然而针对大跨度空间结构振动控制的应用研究还鲜见报道。本文针对大跨度空间结构特点,深入研究了基于MR阻尼器的半主动控制算法,并系统研究了应用MR阻尼器对多维多点地震激励的大跨度空间结构的半主动控制,从而建立了多维多点地震激励的大跨度空间结构基于MR阻尼器的智能半主动控制体系。论文主要研究工作和创新成果如下:(1)研究了多维地震激励的大跨度空间结构的MR阻尼器半主动控制。将MR阻尼器半主动控制系统应用到三维空间结构中,推导了线性二次型调节器(LQR)空间最优控制力的表达式,并由此建立了空间结构的LQR半主动控制算法。数值模拟分析了一个安装有MR阻尼器半主动控制系统的平板网架结构在多维地震激励下的控制效果。研究表明,基于MR阻尼器的半主动控制系统对多维地震激励下的大跨度空间结构具有较为理想的控制效果,可以有效地降低大跨度空间结构的位移和加速度反应。(2)研究了MR阻尼器基于信赖域的瞬时最优半主动控制算法。从磁流变阻尼器的性能出发,利用精细积分法将半主动控制问题描述成带有约束的最小值优化问题,提出了一种基于信赖域的瞬时最优半主动控制算法。通过一三层框架结构的数值模拟以及在dSPACE平台上一悬臂梁的模型试验对该控制算法的有效性进行了验证。研究表明,所提出的基于信赖域的瞬时最优半主动控制算法在结构均方根值反应的控制上有更好的控制效果;且当结构中采用多个阻尼器时的控制效果较传统控制算法更具优越性。同时发现,半主动控制器时间步长的选取对该控制算法的控制效果有很大的影响。(3)研究了多维多点地震激励的大跨度空间结构基于信赖域的MR阻尼器瞬时最优半主动控制。建立了多维多点激励下大跨度空间结构振动控制方程,将基于信赖域的瞬时最优半主动控制算法应用于多维多点激励的大跨度空间结构振动控制。针对大跨度空间结构地震反应的特点,数值模拟分析了应用该信赖域瞬时最优半主动控制算法对一致激励或具有不同视波速的行波激励的大跨度空间结构地震反应的控制效果。研究表明,在多维多点地震激励下,所建立的半主动控制系统可以有效地控制大跨度空间结构的地震反应;且所提出的基于信赖域的瞬时最优半主动控制算法具有更好的稳定性和更优越的控制效果。(4)研究了不同激励下大跨度空间结构基于小波包分解的MR阻尼器模态半主动控制。针对大跨度空间结构自由度庞大、频率密集的特点,引入小波包分解方法对结构的地震反应信号进行分解,通过比较不同频段的小波包能量,确定结构主要参振振型,设计模态控制器,从而改进了传统的模态半主动控制算法。其中所设计的Kalman滤波估计器可大幅度减小控制方程的维数和控制系统所需的传感器数目,从而提高了半主动控制系统的效率和实用性。数值仿真分析了应用基于小波包分解的模态半主动控制算法对竖向地震激励的某体育场挑篷结构和一受多维多点地震激励的大跨度空间结构的半主动控制效果。研究表明,所提出的基于小波包分解的模态半主动控制算法能有效地提高传统模态控制算法的控制效果,且对不同的地震激励有更好的适应性。另外,与所提出的基于信赖域的瞬时最优半主动控制算法相比,基于小波包分解的模态半主动控制算法具有更好的控制效率和实用性。更多还原

【Abstract】 In recent years, lots of long-span building structures have been constructed in China. Because of the huge degree-of-freedom and its complex spatial characteristic, their safety under earthquake excitation has received more and more attention. Magnetorheological (MR) damper have been widely used in the field of civil engineering structures to protect them from earthquake and high winds. However, few efforts have been devoted to the application of MR damper to long-span spatial structures. In this dissertation, MR damper-based semi-active control system is introduced to long-span spatial structure for seismic protection. The main work and achievement are as follows:(1) The feasibility of the application of semi-active control system on long-span spatial structure is first studied. The expression of linear quadratic regulator (LQR) optimal control force in three-dimensional cases is deduced. Numerical simulation is performed on a seismic excited lattice structure installed with MR damper. The results show that both the displacement and acceleration responses of the spatial structure can be reduced greatly by the semi-active control system.(2) Based on the dynamic characteristic of MR damper, a semi-active control problem is described as a constrained optimization problem by using precise integration method. And a trust-region based instantaneous optimal semi-active control (TIOC) algorithm for magnetorheological (MR) dampers is proposed. The effectiveness of the semi-active control algorithm is verified through a numerical example of a seismic excited three-story frame and a control experiment on an MR damper controlled cantilever beam. Both simulation and experimental results indicate the better control effectiveness of the proposed controller on reducing the root-mean-square responses, and the superiority of the proposed controller during multi-dampers situation is also demonstrated. It is found that the time interval of the controller may greatly affect the control effectiveness of the semi-active controller.(3) By using trust-region based instantaneous optimal semi-active control algorithm, the semi-active control of long-span spatial structure is studied. The basic control equation of long-span spatial structure under multi-dimensional and multi-point excitation is first set up. Then the effectiveness of the TIOC controller is evaluated though a numerical example of a long-span spatial structure under both multi-dimensional uniform earthquake excitation and travelling-wave excitation with different apparent velocities. The simulation results indicate that the MR fluid damper-based semiactive control systems have the potential for mitigating the responses of full-scale long-span spatial structures under earthquake hazards. The superiority and stability of the proposed TIOC controller is demonstrated by comparing the control effectiveness with that of the traditional semi-active controller in different cases.(4) Because of the huge degrees-of-freedom and the close-spaced natural frequencies of long-span spatial structure, a novel modal controller incorporated with wavelet packet transform (WPT) is proposed. In the proposed control system, the WPT method is utilized to decompose the acceleration measurement and select those modes containing most of the WPT energy component as the dominant modes. Then, a modal controller is designed to control these dominant modes. A Kalman-filter observer, which estimates the full controlled modal states from local accelerometer outputs, is designed for reducing the number of required sensors and the dimension of control equation and rendering the controller to be more applicable to spatial structures with a large number of degrees of freedom (DOFs). The effectiveness of the semi-active controller is demonstrated through two numerical examples: An MRF-04K damper controlled stadium roof structure subjected to vertical excitation, and a long-span spatial structure subjected to multi-dimensional and multi-point earthquake excitation. Simulation results show that the control effectiveness of the traditional modal controller can be improved by WPT-based modal controller. And comparing to TIOC controller, WPT modal controller can be more efficient and more practical in real project application.更多还原