In the context of vibration based Structural Health Monitoring using automated operational modal analysis, data synchronization methods permit a reduction in the cost of wireless monitoring systems, since the use of extra hardware for perfect data synchronization can be avoided. Furthermore, the relaxation of data synchronization requirements permits a more flexible topology (higher distance between sensors, no need of external antennas for data synchronization using GPS, lower power consumption), which is particularly advantageous in the dynamic monitoring of large structures. In this paper, continuous dynamic monitoring without real-time synchronization is studied. Firstly, using numerical simulations, the effects of synchronicity faults on operational modal analysis is deeply analysed, showing that time delays have a great impact on modal identification. Secondly, a new data synchronization method based on mode shapes identified with operational modal analysis methods is proposed to improve the accuracy of modal identification. This does not need the assumption of proportional damping. Therefore, it overcomes this limitation that up to the knowledge of the authors is present in all other available methods. The proposed processing strategy is validated in the processing of monitoring data continuously collected at a long span arch bridge (Infante D. Henrique Bridge) with two wireless acceleration nodes. The full-scale application shows high time synchronization accuracy and proves that the proposed synchronization method is adequate for continuous dynamic monitoring, providing reliable modal parameters estimates with any assumptions about the damping, permitting a reduction in the monitoring costs, easier installation and power consumption reductions (very important to increase the autonomy of wireless nodes). In short, hardware costs are replaced by a smarter processing.

在基于振动的结构健康监测中，使用自动化的运行模式分析，数据同步方法可以降低无线监测系统的成本，因为可以避免使用额外的硬件来实现完美的数据同步。此外，对数据同步要求的放宽允许拓扑结构更加灵活（传感器之间的距离更长，不需要使用GPS进行数据同步的外部天线，功耗更低），这在大型结构的动态监控中特别有利。本文研究了没有实时同步的连续动态监控。首先，通过数值模拟，深入分析了同步故障对运行模态分析的影响，表明时间延迟对模态识别有很大影响。其次，提出了一种新的基于模态形状的数据同步方法，该模态形状由操作模态分析方法确定，以提高模态识别的准确性。不需要假设比例阻尼，因此它克服了所有其他可用方法中存在作者知识的限制。所提出的处理策略在具有两个无线加速节点的大跨度拱桥（Infante D. Henrique桥）连续收集的监测数据的处理中得到了验证。全面应用显示了较高的时间同步精度，并证明了所提出的同步方法足以进行连续动态监视，在对阻尼有任何假设的情况下，证明可靠的模态参数估计值，可以降低监控成本，简化安装并降低功耗（对于增加无线节点的自主性非常重要）。简而言之，硬件成本被更智能的处理所取代。