An improved EMD method for modal identification and a combined static-dynamic method for damage detection

Yang, Jinping; Li, Peizhen; You-fa, Yang; Xu, Dongyu

doi:10.1016/j.jsv.2018.01.036

Cited by 44 publications

(22 citation statements)

References 43 publications

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“…The model frequencies and damping ratio identified by the improved empirical mode decomposition method in the PS6 test and RS6 test are shown in Table , which demonstrates that the model frequency decreases and the damping ratio increases with the increase of PGA. This is because the soil becomes softer and more nonlinear, and the stiffness of the pile foundation and superstructure decreases as the PGA of input excitation increases.…”

Section: Test Phenomena and Dynamic Characteristics Of The Modelsmentioning

confidence: 98%

Large‐scale shaking table test on pile‐soil‐structure interaction on soft soils

Yang

Lü

2019

Structural Design Tall Build

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SUMMARY The two large‐scale shaking table tests of tall buildings on soft soils in pile group foundations are performed to capture the effect of the seismic pile‐soil‐structure interaction (PSSI) on the dynamic responses of the pile, soil, and structure. The two different model conditions are observed, including a fixed‐base structure and a structure supported by 3‐by‐3 pile group foundation in soft soil, representing the situations excluding the soil‐structure interaction (SSI) and considering the SSI, respectively. In the tests, the superstructure is a tall building with 12‐story reinforced concrete frame. The pile‐soil‐structure system rests in a shear laminar soil container, which is designed to minimize the boundary effects during shaking table tests. The two models are subjected to various intensity seismic excitations of Shanghai bedrock waves, 1995 Kobe earthquake, and 1999 Chi‐Chi earthquake events. According to the experimental and analytical results, SSI systems have longer natural periods than the fixed‐base structure. In addition, soft soil has amplification effect under smaller seismic excitations and isolation effects under larger earthquake intensities. The strain amplitude at the top of pile is large, and the strain at the middle and tip is relatively small. Whereas the contact pressure is small at the top of pile and large at the middle and tip. From the dynamic responses of the superstructure, it is found that the PSSI amplifies the peak displacements and interstory drifts of the structures supported by pile group foundations by comparing with the fixed‐base structure. Whereas the peak acceleration and interstory shear force of the structure are reduced considering seismic PSSI. The results show that the seismic SSI is not always favorable, however, it may increase certain dynamic responses of the structure. Consequently, the seismic SSI should be considered reasonably, providing insight towards the rational seismic design of buildings rested on soft soils.

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Section: Test Phenomena and Dynamic Characteristics Of The Modelsmentioning

confidence: 98%

Large‐scale shaking table test on pile‐soil‐structure interaction on soft soils

Yang

Lü

2019

Structural Design Tall Build

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“…As described in Section 2 given a raw vibration signal ( ) Among all the adaptive decomposition algorithms, EMD is the one that is earliest proposed and obtains the most applications in fault diagnosis. However, the EMD has the problem called mode mixing [23]. Although, EEMD, a variant of EMD had been proposed to deal with this problem through the ensemble of original signal with Gaussian noise.…”

Section: Ceemd-based Signal Processingmentioning

confidence: 99%

TF Entropy and RFE Based Diagnosis for Centrifugal Pumps Subject to the Limitation of Failure Samples

Liu

Tao

2020

Applied Sciences

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In practical engineering, the vibration-based fault diagnosis with few failure samples is gaining more and more attention from researchers, since it is generally hard to collect sufficient failure records of centrifugal pumps. In such circumstances, effective feature extraction becomes quite vital, since there may not be enough failure data to train an end-to-end classifier, like the deep neural network (DNN). Among the feature extraction, the entropy combined with signal decomposition algorithms is a powerful choice for fault diagnosis of rotating machinery, where the latter decomposes the non-stationary signal into multiple sequences and the former further measures their nonlinear characteristics. However, the existing entropy generally aims at processing the 1D sequence, which means that it cannot simultaneously extract the fault-related information from both the time and frequency domains. Once the sequence is not strictly stationary (hard to achieve in practices), the useful information will be inevitably lost due to the ignored domain, thus limiting its performance. To solve the above issue, a novel entropy method called time-frequency entropy (TfEn) is proposed to jointly measure the complexity and dynamic changes, by taking into account nonlinear behaviors of sequences from both dimensions of time and frequency, which can still fully extract the intrinsic fault features even if the sequence is not strictly stationary. Successively, in order to eliminate the redundant components and further improve the diagnostic accuracy, recursive feature elimination (RFE) is applied to select the optimal features, which has better interpretability and performance, with the help of the supervised embedding mechanism. To sum up, we propose a novel two-stage method to construct the fault representation for centrifugal pumps, which develops from the TfEn-based feature extraction and RFE-based feature selection. The experimental results using the real vibration data of centrifugal pumps show that, with extremely few failure samples, the proposed method respectively improves the average classification accuracy by 12.95% and 33.27%, compared with the mainstream entropy-based methods and the DNN-based ones, which reveals the advantage of our methodology.

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“…Based on the acceleration responses of the structure on the top floor, the dynamic characteristics of the six models in the shaking table tests can be identified by the improved EMD method, [35] and the results are listed in Table 3, and the frequencies of the six models are shown in Figure 3.…”

Section: Dynamic Characteristics Of the Test Modelsmentioning

confidence: 99%

Dynamic characteristics and viscous dampers design for pile‐soil‐structure system

Yang

Jing

2020

Structural Design Tall Build

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Summary A series of large‐scale shaking table tests are conducted on tall buildings with and without energy dissipation devices on soft soils in pile group foundations, representing pile‐soil‐structure interaction (PSSI) system and the corresponding fixed‐base situations. The superstructure is a 12‐story reinforced concrete (RC) frame. The dynamic characteristics of the test models show that the frequencies decrease and the damping ratio increase in PSSI system by comparison with the fixed‐base structures. The mode shapes of PSSI system are different from that under fixed‐base condition, and the mode shapes of structure without dampers change greater than that with energy dissipation devices under various white noises. An improved method for structural dynamic characteristics, considering the impedance function of piles, is developed to address the issue of modal parameters with PSSI effect. In addition, the structural dynamic parameters of the large‐scale shaking table tests are identified using the modification method and other regulation methods, demonstrating that the improved approach is highly accurate and effective. Subsequently, a design procedure for viscous dampers of structures with PSSI effect is presented based on the dynamic characteristics of the system. Finally, the dynamic responses of the structure with viscous dampers in the practical engineering are decreased effectively, indicating the good performance of designed viscous dampers. The numerical results also show that the damping efficiency of interstory drift is larger than the acceleration and interstory shear force. Therefore, the improved modal parameters method, validated through a series large‐scale shaking table tests, is applicable for identifying dynamic characteristics of pile‐soil‐structure with energy dissipation devices system. The design procedure of viscous dampers, proved by a reinforced concrete frame structure located on a practical Shanghai soft site, can be employed to design the viscous dampers considering seismic PSSI effect.

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An improved EMD method for modal identification and a combined static-dynamic method for damage detection

Cited by 44 publications

References 43 publications

Large‐scale shaking table test on pile‐soil‐structure interaction on soft soils

Large‐scale shaking table test on pile‐soil‐structure interaction on soft soils

TF Entropy and RFE Based Diagnosis for Centrifugal Pumps Subject to the Limitation of Failure Samples

Dynamic characteristics and viscous dampers design for pile‐soil‐structure system

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