智能预应力简支钢桁梁及其在移动质量作用下的挠度控制研究

According to the fabricated steel truss girder's requirements on both weight and deflection, a new structure which is named deflection controllable light smart prestressed steel truss girder is put forward. Based on smart external prestressed technology, this structure can dynamically control its deflection by actively adjusting the external prestressing under the effect of changes in external action and internal performance. In this proposed research project, firstly, the dynamic model of a smart prestressed simply-supported steel truss girder under a uniform moving mass will be set up by applying the d'Alembert principle. Then, based on the Simulink environment, the influence rule of control performance parameters under slow moving condition, in which the switch control is adopted, will be investigated and the simplified design method for the smart prestressed simply-supported steel truss girder will be put forward. Furthermore, the influence rule of control stability parameters under normal moving condition, in which the fuzzy adaptive PID control is adopted, will be investigated and the ensure measure for the smart prestressed simply-supported steel truss girder's control stability will be put forward. Finally, a novel smart anchor which is based on direct driven electro-hydraulic servo system will be used to build an experimental platform for smart prestressed steel truss girder's deflection control, and then the deflection control theory will be tested and modified. The proposed research project can contribute to the development of changeable prestressed technology and prestressed steel truss girder's design method.

针对装配式钢桁梁在重量和变形方面的双重需求，提出挠度可控的轻型智能预应力钢桁梁新结构，该结构采用智能体外预应力技术，在外界作用和内在性能变化的影响下，通过智能锚具的伸缩主动调整体外预应力的大小，从而实现对结构挠度的动态控制。在此思路引导下，首先运用达朗贝尔原理，建立智能预应力简支钢桁梁在匀速移动质量作用下的系统动力学模型。然后基于Simulink仿真平台，采用开关控制算法，对缓慢移动时的控制性能参数影响规律进行仿真研究，提出智能预应力简支钢桁梁的简化设计方法，此外，采用模糊自适应PID控制算法，对常速移动时的控制稳定性参数影响规律进行仿真研究，提出智能预应力简支钢桁梁的控制稳定性保障措施。最后采用直驱式容积控制电液伺服系统研发新型智能锚具，构建智能预应力简支钢桁梁挠度控制试验平台，检验、修正智能预应力简支钢桁梁的挠度控制理论。课题研究有助于可调预应力技术和预应力钢桁梁桥设计理论的发展。

智能预应力技术，能够根据结构状态主动调整预应力，可以达到提高结构承载性能、优化结构服役状态的目的。当对结构重量和变形有严格要求而常规预应力技术又难以实现时，智能预应力技术提供了一条可行的新思路。本项目完成的智能预应力技术应用基础研究内容主要包括：推导了智能预应力简支梁控制微分方程，研究了智能预应力混凝土箱梁的约束承载性能；仿真分析了智能预应力钢桁梁的活载可变范围，研究了相关约束参数对其承载性能的影响；建立了匀速移动质量作用下智能预应力梁的车桥耦合振动力学模型，并基于提出的多级控制算法，对比分析了无控制、单级控制以及多级控制智能预应力简支梁在不同移动工况下的动力响应，并讨论了各控制参数对受控简支梁挠度的影响；进行了智能斜拉桥模型主梁跨中应变控制试验，验证了所提多级控制算法的有效性；进行了智能预应力钢桁梁模型跨中挠度控制试验，验证了智能预应力钢桁梁有限元仿真分析结论。本研究有助于实现一种智能预应力简支钢桁梁新结构，对灾后生命线抢通的快速化、大跨施工支架的轻型化以及超大吨位结构的运输和安装等具有重要意义。