步行荷载下大跨楼盖MTMD控制参数优化方法研究

摘要

采用多重调谐质量阻尼器（MTMD）来控制大跨楼盖由于行人引起的竖向振动，已被工程实践证明为一种行之有效的减振方法。然而由于步行荷载的时空复杂性，采用有限元时程分析方法进行MTMD最优参数设计时的计算成本过高，甚至难以实现。为此，提出一种步行荷载下大跨楼盖-MTMD参数优化的混合算法，利用有限元获得楼盖模态后再由振型分解法计算移动步行荷载引起的结构响应，进一步结合遗传算法，研究考虑结构动力特性变化的MTMD参数优化问题。最后，以某体外预应力楼盖为例进行了MTMD频率和阻尼比的优化设计，讨论了楼盖固有频率和阻尼比变化对减振效率的影响，对比了考虑与不考虑结构特征改变的MTMD参数优化结果。结果表明，所建议的混合算法可显著提升计算效率并获得优化的控制参数，可用于同类大跨楼盖MTMD控制参数设计问题。%Using multiple tuned mass dampers (MTMDs)is proved to be an effective way to reduce pedestrian-induced excessive floor vibrations.However,the optimization of MTMD parameters based on FEM software is very time-consuming,even too difficult to realize,due to the time-spatial variation feature of pedestrian's walking loads.To solve this problem,a hybrid calculation approach was proposed here.Withit,the modal properties of a floor were firstly determined with FEM software and the floor's dynamic responses were then calculated using the modal superposition theory under the walking loads.Based on this efficient calculation approach,the optimal frequencies and damping ratios of MTMDs were determined with the genetic algorithm.Taking an existing long span concrete floor as an example,the optimal MTMD parameters,i.e.,number of TMDs,locations,frequencies and damping ratios were designed.The MTMD off-tuning effect due to variation of floor's natural frequencies and damping ratios was also investigated.The results showed that the suggested approach greatly improves the computation efficiency and the optimized MTMD parameters are reliable and robust to variation of structural properties.