A robust real-time damage detection technique of earthquake-excited structures based on a new demodulation technique for nonlinear and non-stationary vibration signals through the identification of signal envelopes in real time is presented. In the present work, the need for the detection of envelope in a vibration signal in real time is addressed by reformulating the concept of Hermitian interpolation functions to a recursive Hermitian polynomial, which is a key entitlement of the present work. Once, the near real-time demodulation is achieved, the proposed framework proceeds to the newly developed error-adapted framework by addressing the errors accrued between the standard and generalized eigen perturbation formulation in the context of real-time estimation of proper orthogonal modes and linear normal modes. In the adaptive framework, the error is modeled as a feedback, which is constructed to account for the truncation in the order of eigen perturbation. In addition to the improved accuracy due to the envelope extraction, the proposed error-adapted eigen perturbation further improves the detectability over the currently available eigen perturbation–based real-time algorithms. To ensure robustness of the proposed algorithm, a new real-time damage indicator based on the maximum of principal eigenvector of the evolving transformed covariance matrix is proposed. The proposed modules together not only improve the detectability of the damage detection in real-time but also enhance the overall performance in presence of non-stationary excitation, that often mask the damage information in the higher energy zones of the amplitude and frequency-modulated response. Simulations for the proposed framework is performed by considering a 5 degrees-of-freedom linear and base-isolated nonlinear structural system driven by non-stationary stochastic excitations with damage simulated at intermediate floor at a particular time instant. Evidence of the near real-time demodulation and/or envelope removal from the signal and improved damage identification is also provided. An examination of the proposed framework using experimental data further validates the robustness of the proposed scheme.

通过实时识别信号包络，提出了一种基于非线性和非平稳振动信号解调技术的鲁棒地震结构实时损伤检测技术。在当前工作中，通过将Hermitian插值函数的概念重新构造为递归的Hermitian多项式，可以满足实时检测振动信号中包络的需要，这是当前工作的关键。一旦实现了近实时解调，在实时估计适当正交模式和线性模型的情况下，通过解决标准和广义本征摄动公式之间产生的误差，拟议的框架便进入了新开发的误差适应框架。正常模式。在适应性框架中，该误差被建模为一个反馈，该反馈被构造为以本征扰动的顺序考虑到截断。除了由于包络提取而提高了精度外，与现有的基于本征扰动的实时算法相比，拟议的自适应误差本征扰动还进一步提高了可检测性。为了保证算法的鲁棒性，提出了一种基于演化变换协方差矩阵主特征向量最大值的实时损伤指标。所提出的模块不仅可以提高实时检测损坏的能力，而且还可以提高在存在非平稳激励的情况下的整体性能，这种激励通常会掩盖振幅和频率响应较高能量区域中的损坏信息。 。拟议框架的仿真是通过考虑由非平稳随机激励驱动的5自由度线性和基础隔离的非线性结构系统进行的，在特定时刻在中间楼层模拟了损伤。还提供了从信号中进行近实时解调和/或包络去除以及改进的损伤识别的证据。使用实验数据对提出的框架进行的检查进一步验证了提出的方案的鲁棒性。还提供了从信号中进行近实时解调和/或包络去除以及改进的损伤识别的证据。使用实验数据对提出的框架进行的检查进一步验证了提出的方案的鲁棒性。还提供了从信号中进行近实时解调和/或包络去除以及改进的损伤识别的证据。使用实验数据对提出的框架进行的检查进一步验证了提出的方案的鲁棒性。