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Relative Motions in Multiple Caisson Units on Damaged Foundation
Thanh-Canh Huynh,So-Young Lee,Jeong-Tae Kim,Sang-Hun Han 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5
This study presents the relative motions in multiple caisson units due to foundation damage. To obtain the objective, the following approaches are performed. Firstly, a finite element (FE) model cf two-caisson system with simulation sail-structure interaction is established in commercial software ANSYS in order to investigate relative motions in harbor caisson system Secondly, relative displacement of caisson units under various foundation damage scenarios is measured from static and dynamic states. Thirdly, the results are analyzed to monitor the health condition of the target harbor caisson.
Thanh-Canh Huynh,Jeong-Tae Kim 국제구조공학회 2016 Smart Structures and Systems, An International Jou Vol.17 No.6
In this study, a method to compensate the effect of temperature variation on impedance responses which are used for prestress-loss monitoring in prestressed concrete (PSC) girders is presented. Firstly, an impedance-based technique using a mountable lead-zirconate-titanate (PZT) interface is presented for prestress-loss monitoring in the local tendon-anchorage member. Secondly, a cross-correlation-based algorithm to compensate the effect of temperature variation in the impedance signatures is outlined. Thirdly, lab-scale experiments are performed on a PSC girder instrumented with a mountable PZT interface at the tendon-anchorage. A series of temperature variation and prestress-loss events are simulated for the lab-scale PSC girder. Finally, the feasibility of the proposed method is experimentally verified for prestress-loss monitoring in the PSC girder under temperature-varying conditions and prestress-loss events.
PCA-based filtering of temperature effect on impedance monitoring in prestressed tendon anchorage
Thanh-Canh Huynh,Ngoc-Loi Dang,Jeong-Tae Kim 국제구조공학회 2018 Smart Structures and Systems, An International Jou Vol.22 No.1
For the long-term structural health monitoring of civil structures, the effect of ambient temperature variation has been regarded as one of the critical issues. In this study, a principal component analysis (PCA)-based algorithm is proposed to filter out temperature effects on electromechanical impedance (EMI) monitoring of prestressed tendon anchorages. Firstly, the EMI monitoring via a piezoelectric interface device is described for prestress-loss detection in the tendon anchorage system. Secondly, the PCA-based temperature filtering algorithm tailored to the EMI monitoring of the prestressed tendon anchorage is outlined. The proposed algorithm utilizes the damage-sensitive features obtained from sub-ranges of the EMI data to establish the PCA-based filter model. Finally, the feasibility of the PCA-based algorithm is experimentally evaluated by distinguishing temperature changes from prestress-loss events in a prestressed concrete girder. The accuracy of the prestress-loss detection results is discussed with respect to the EMI features before and after the temperature filtering.
Simplified planar model for damage estimation of interlocked caisson system
Thanh-Canh Huynh,김정태,이소영,박우선,한상훈 국제구조공학회 2013 Smart Structures and Systems, An International Jou Vol.12 No.4
In this paper, a simplified planar model is developed for damage estimation of interlocked caisson systems. Firstly, a conceptual dynamic model of the interlocked caisson system is designed on the basis of the characteristics of existing harbor caisson structures. A mass-spring-dashpot model allowing only the sway motion is formulated. To represent the condition of interlocking mechanisms, each caisson unit is connected to adjacent ones via springs and dashpots. Secondly, the accuracy of the planar model‟s vibration analysis is numerically evaluated on a 3-D FE model of the interlocked caisson system. Finally, the simplified planar model is employed for damage estimation in the interlocked caisson system. For localizing damaged caissons, a damage detection method based on modal strain energy is formulated for the caisson system.
Thanh-Truong Nguyen,Jeong-Tae Kim,Quoc-Bao Ta,Duc-Duy Ho,Thi Tuong Vy Phan,Thanh-Canh Huynh 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.1
The piezoelectric-based smart interface technique has shown promising prospects for electro-mechanical impedance (EMI)-based damage detection with various successful applications. During the process of EMI monitoring and damage identification, the operational functionality of the smart interface device is a major concern. In this study, common functional degradations that occurred in the smart interface are diagnosed using a deep learning-based method. Firstly, the effect of functional degradations on the EMI responses is analytically discussed. Secondly, a critical structural joint is selected as the test structure from which EM measurement using the smart interface is conducted. Thirdly, a numerical model corresponding to the experimental model is established and updated to reproduce the measured EMI responses. By using the updated numerical model, the EMI responses of the smart interface under the common functional degradations, such as the shear lag effect, the adhesive debonding, the sensor breakage, and the interface detaching, are simulated; then, the functional degradation-induced EMI changes are characterized. Finally, a convolutional neural network (CNN)-based functional assessment method is newly proposed for the smart interface. The CNN can automatically extract and directly learn optimal features from the raw EMI signals without preprocessing. The CNN is trained and tested using the datasets obtained from the updated numerical model. The obtained results show that the proposed method was successful to classify four types of common defects in the smart interface, even under the effect of noises.
Relative Motions in Multiple Caisson Units on Damaged Foundation
Thanh-Canh Huynh,So-Young Lee,Jeong-Tae Kim,Sang-Hun Han 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5
This study presents the relative motions in multiple caisson units due to foundation damage. To obtain the objective, the following approaches are performed. Firstly, a finite element (FE) model of two-caisson system with simulation soil-structure interaction is established in commercial software ANSYS in order to investigate relative motions in harbor caisson system. Secondly, relative displacement of caisson units under various foundation damage scenarios is measured from static and dynamic states. Thirdly, the results are analyzed to monitor the health condition of the target harbor caisson.
Structural Damage Monitoring of Harbor Caissons with Interlocking Condition
Thanh-Canh Huynh,So-Young Lee,Khac-Duy Nguyen,Jeong-Tae Kim 한국비파괴검사학회 2012 한국비파괴검사학회지 Vol.32 No.6
The objective of this study is to monitor the health status of harbor caissons which have potential foundation damage. To obtain the objective, the following approaches are performed. Firstly, a structural damage monitoring(SDM) method is designed for interlocked multiple-caisson structures. The SDM method utilizes the change in modal strain energy to monitor the foundation damage in a target caisson unit. Secondly, a finite element model of a caisson system which consists of three caisson units is established to verify the feasibility of the proposed method. In the finite element simulation, the caisson units are constrained each other by shear-key connections. The health status of the caisson system against various levels of foundation damage is monitored by measuring relative modal displacements between the adjacent caissons.
Huynh, Thanh-Canh,Lee, Kwang-Suk,Kim, Jeong-Tae Techno-Press 2015 Smart Structures and Systems, An International Jou Vol.15 No.2
In this study, local dynamic characteristics of mountable PZT interfaces are numerically analyzed to verify their feasibility on impedance monitoring of the prestress-loss in tendon anchorage subsystems. Firstly, a prestressed tendon-anchorage system with mountable PZT interfaces is described. Two types of mountable interfaces which are different in geometric and boundary conditions are designed for impedance monitoring in the tendon-anchorage subsystems. Secondly, laboratory experiments are performed to evaluate the impedance monitoring via the two mountable PZT interfaces placed on the tendon-anchorage under the variation of prestress forces. Impedance features such as frequency-shifts and root-mean-square-deviations are quantified for the two PZT interfaces. Finally, local dynamic characteristics of the two PZT interfaces are numerically analyzed to verify their performances on impedance monitoring at the tendon-anchorage system. For the two PZT interfaces, the relationships between structural parameters and local vibration responses are examined by modal sensitivity analyses.
Impedance-Based Cable Force Monitoring in Tendon-Anchorage Using Portable PZT-Interface Technique
Huynh, Thanh-Canh,Kim, Jeong-Tae Hindawi Limited 2014 Mathematical problems in engineering Vol.2014 No.-
<P>In this paper, a portable PZT interface for tension force monitoring in the cable-anchorage subsystem is developed. Firstly, the theoretical background of the impedance-based method is presented. A few damage evaluation approaches are outlined to quantify the variation of impedance signatures. Secondly, a portable PZT interface is designed to monitor impedance signatures from the cable-anchorage subsystem. One degree-of-freedom analytical model of the PZT interface is established to explain how to represent the loss of cable force from the change in the electromechanical impedance of the PZT interface as well as reducing the sensitive frequency band by implementing the interface device. Finally, the applicability of the proposed PZT-interface technique is experimentally evaluated for cable force-loss monitoring in a lab-scaled test structure.</P>