土结构动力相互作用的实时耦联动力试验的时滞稳定性

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.

DELAY-DEPENDENT STABILITY OF REAL-TIME DYNAMIC HYBRID TESTING FOR SOIL-STRUCTURE INTERACTION ANALYSIS

Taking a single degree-of-freedom structural system as an example,the mathematical model of real-time dynamic hybrid testing for soil-structure interaction analysis(SSI-RTDHT) is established,where shaking table response delay and delay compensation strategy are included.Then the stability of the time-delayed system is investigated using the root locus technique based on Padé decomposition approximating the delay term.Finally,some numerical experiments are performed to validate the obtained stability conditions.The results show that the performance of the inherent mode is changed and SSI-RTDHT becomes conditionally stable due to the delay;the stability is worsen with increasing of the delay and the natural frequency of upper structure,and it is improved with increasing of the characteristic frequency of the foundation;the influence of the damping ratio of the upper structure on the stability is relatively small.The results also show that third-order polynomial compensation will make the stability worse,but it can improve the performance of the inherent mode.