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针对土-结构动力相互作用的实时耦联动力试验(SSI-RTDHT),以单自由度上部结构体系为例,建立了考虑振动台时滞及其补偿的数学模型;然后采用基于Padé展开逼近时滞项的根轨迹方法研究其稳定性;最后利用数值仿真验证了理论分析得出的稳定条件。研究结果表明:时滞明显地改变了系统固有模态的动力特性,并使得SSI-RTDHT成为一个条件稳定系统;稳定性随时滞和上部结构频率的增大而降低,随地基特征频率的增大而提高;上部结构阻尼比对稳定性影响不大。三阶多项式补偿会明显降低试验体系的稳定性,但可以改善固有模态的性能。
Aiming at the real-time coupling dynamic test (SSI-RTDHT) of soil-structure dynamic interaction, taking the single-degree-of-freedom superstructure as an example, a mathematical model considering the shaking table delay and its compensation is established. Then, The root locus of the hysteresis is used to study the stability of the hysteresis. Finally, numerical simulation is used to verify the stability of the theoretical analysis. The results show that the time delay significantly changes the dynamic characteristics of the natural modes of the system and makes the SSI-RTDHT a conditionally stable system. The stability decreases with time lag and the increase of the superstructure frequency. With the increase of the characteristic frequency of the foundation While the superstructure damping ratio has little effect on the stability. Third-order polynomial compensation can significantly reduce the stability of the experimental system, but can improve the inherent mode performance.