• Title/Summary/Keyword: Damage Function

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Damage Assessment of Existing Structures by System Identification (SI법에 의한 기설구조물의 손상평가)

  • Lee, Hee-Up;Yang, Chang-Hyun;Park, Moon-Suk
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.3 no.1
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    • pp.179-184
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    • 1999
  • In this study, a method for damage assessment of existing structures is suggested using system identification approach. The natural frequencies of damaged structures are utilized to determine the size of damage. The SUMT algorithm is used to minimize error of the criterion function. The structural analysis is performed by using finite element method. Numerical examples are carried out to verify the validity of the proposed method and its computational procedures. And damage estimation of PSC beam is performed to demonstrate the effectiveness of the proposed method. From the results, it is found that the proposed SI method can be applied to estimate damage in existing structures accurately and rapidly.

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Damage detection of multistory shear buildings using partial modal data

  • Shah, Ankur;Vesmawala, Gaurang;Meruane, V.
    • Earthquakes and Structures
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    • v.23 no.1
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    • pp.1-11
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    • 2022
  • This study implements a hybrid Genetic Algorithm to detect, locate, and quantify structural damage for multistory shear buildings using partial modal data. Measuring modal responses at multiple locations on a structure is both challenging and expensive in practice. The proposed method's objective function is based on the building's dynamic properties and can also be employed with partial modal information. This method includes initial residuals between the numerical and experimental model and a damage penalization term to avoid false damages. To test the proposed method, a numerical example of a ten-story shear building with noisy and partial modal information was explored. The obtained results were in agreement with the previously published research. The proposed method's performance was also verified using experimental modal data of an 8-DOF spring-mass system and a five-story shear building. The predicted results for numerical and experimental examples indicated that the proposed method is reliable in identifying the damage for multistory shear buildings.

Experimental damage identification of cantilever beam using double stage extended improved particle swarm optimization

  • Thakurdas Goswami;Partha Bhattacharya
    • Structural Engineering and Mechanics
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    • v.91 no.6
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    • pp.591-606
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    • 2024
  • This article proposes a new methodology for identifying beam damage based on changes in modal parameters using the Double Stage Extended Improved Particle Swarm Optimization (DSEIPSO) technique. A finite element code is first developed in MATLAB to model an ideal beam structure based on classical beam theory. An experimental study is then performed on a laboratory-scale beam, and the modal parameters are extracted. An improved version of the PSO algorithm is employed to update the finite element model based on the experimental measurements, representing the real structure and forming the baseline model for all further damage detection. Subsequently, structural damages are introduced in the experimental beam. The DSEIPSO algorithm is then utilized to optimize the objective function, formulated using the obtained mode shapes and the natural frequencies from the damaged and undamaged beams to identify the exact location and extent of the damage. Experimentally obtained resultsfrom a simple cantilever beam are used to validate the effectiveness of the proposed method. The illustrated results show the effectiveness of the proposed method for structural damage detection in the SHM field.

A New Yield Function for Voided Materials (보이드 재료에 대한 새로운 항복함수의 제안)

  • 김성태
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2000.04a
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    • pp.13-16
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    • 2000
  • In this paper the authors proposed a new anisotropic yield criterion for porous ductile materials. By using the proposed yield criterion and its flow rules a damage evolution of anisotropic sheet under biaxial tensile loading is investigated. A comparison of yield locus and damage evolution between the proposed yield criterion and experiments are carried out. the results are in good agreement.

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Active damage localization technique based on energy propagation of Lamb waves

  • Wang, Lei;Yuan, F.G.
    • Smart Structures and Systems
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    • v.3 no.2
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    • pp.201-217
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    • 2007
  • An active damage detection technique is introduced to locate damage in an isotropic plate using Lamb waves. This technique uses a time-domain energy model of Lamb waves in plates that the wave amplitude inversely decays with the propagation distance along a ray direction. Accordingly the damage localization is formulated as a least-squares problem to minimize an error function between the model and the measured data. An active sensing system with integrated actuators/sensors is controlled to excite/receive $A_0$ mode of Lamb waves in the plate. Scattered wave signals from the damage can be obtained by subtracting the baseline signal of the undamaged plate from the recorded signal of the damaged plate. In the experimental study, after collecting the scattered wave signals, a discrete wavelet transform (DWT) is employed to extract the first scattered wave pack from the damage, then an iterative method is derived to solve the least-squares problem for locating the damage. Since this method does not rely on time-of-flight but wave energy measurement, it is more robust, reliable, and noise-tolerant. Both numerical and experimental examples are performed to verify the efficiency and accuracy of the method, and the results demonstrate that the estimated damage position stably converges to the targeted damage.

A fast damage detecting technique for indeterminate trusses

  • Naderi, Arash;Sohrabi, Mohammad Reza;Ghasemi, Mohammad Reza;Dizangian, Babak
    • Structural Engineering and Mechanics
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    • v.75 no.5
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    • pp.585-594
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    • 2020
  • Detecting the damage of indeterminate trusses is of major importance in the literature. This paper proposes a quick approach in this regard, utilizing a precise mathematical approach based on Finite Element Method. Different to a general two-step method defined in the literature essentially based on optimization approach, this method consists of three steps including Damage-Suspected Element Identification step, Imminent Damaged Element Identification step, and finally, Damage Severity Detection step and does not need any optimizing algorithm. The first step focuses on the identification of damage-suspected elements using an index based on modal residual force vector. In the second step, imminent damage elements are identified among the damage-suspected elements detected in the previous step using a specific technique. Ultimately, in the third step, a novel relation is derived to calculate the damage severity of each imminent damaged element. To show the efficiency and quick function of the proposed method, three examples including a 25-bar planar truss, a 31-bar planar truss, and a 52-bar space truss are studied; results of which indicate that the method is innovatively capable of suitably detecting, for indeterminate trusses, not only damaged elements but also their individual damage severity by carrying out solely one analysis.

Damage detection using both energy and displacement damage index on the ASCE benchmark problem

  • Khosraviani, Mohammad Javad;Bahar, Omid;Ghasemi, Seyed Hooman
    • Structural Engineering and Mechanics
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    • v.77 no.2
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    • pp.151-165
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    • 2021
  • This paper aims to present a novelty damage detection method to identify damage locations by the simultaneous use of both the energy and displacement damage indices. Using this novelty method, the damaged location and even the damaged floor are accurately detected. As a first method, a combination of the instantaneous frequency energy index (EDI) and the structural acceleration responses are used. To evaluate the first method and also present a rapid assessment method, the Displacement Damage Index (DDI), which consists of the error reliability (β) and Normal Probability Density Function (NPDF) indices, are introduced. The innovation of this method is the simultaneous use of displacement-acceleration responses during one process, which is more effective in the rapid evaluation of damage patterns with velocity vectors. In order to evaluate the effectiveness of the proposed method, various damage scenarios of the ASCE benchmark problem, and the effects of measurement noise were studied numerically. Extensive analyses show that the rapid proposed method is capable of accurately detecting the location of sparse damages through the building. Finally, the proposed method was validated by experimental studies of a six-story steel building structure with single and multiple damage cases.

Ipsilesional Movement Deficit of Proximal & Distal Upper Extremity in Patients With Unilateral Brain Damage (편측 뇌손상 환자에서 동측 상지의 근위부 및 원위부의 운동 결함에 관한 분석)

  • Kwon, Yong-Hyun;Choi, Jin-Ho;Shin, Hwa-Kyung;Bai, Dai-Seg
    • Physical Therapy Korea
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    • v.12 no.1
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    • pp.71-79
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    • 2005
  • The purpose of this study was to analyze the presence of ipsilesional movement deficit, with segmental performance in each proximal or distal upper extremity. The visuoperceptual complex task of the ipsilesional upper extremity was investigated in patients with unilateral brain damage and a control group of healthy sex-age-matched controls. Tracking movements were tested in the proximal and distal upper extremities. Movements were measured by the accuracy index, which was normalized to each subject's own range of motion and took into account any differences between subjects in the excursion of the tracking target. The findings revealed that stroke patients experienced difficulties with tracking movement of both proximal and distal segments in the upper extremities on the so-called "non-affected side", irrespectively of the extent of patient's age, time since onset, or severity of contralateral upper extremity. Therefore, the unilateral brain damage affected ipsilateral motor function of the proximal and distal upper limbs in the performance of complex motor tasks, requiring central processing and the higher order cognitive function in the integrity of both hemispheres.

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Seismic Fragility Function for Existing Low-Rise Piloti-Type Buildings Reflecting Damage From Pohang Earthquake (포항지진의 피해 결과를 반영한 기존 저층 필로티 건물의 지진취약도함수)

  • Kim, Jinyoung;Kim, Taewan
    • Journal of the Earthquake Engineering Society of Korea
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    • v.25 no.6
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    • pp.251-259
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    • 2021
  • Current seismic fragility functions for buildings were developed by defining damage state threshold based on story drift concerning foreign references and using the capacity spectrum method based on spectral displacement. In this study, insufficient details and dependence on the core location of piloti-type buildings were not reflected in the fragility function because it was developed before the Pohang earthquake. In order to develop an improved one for piloti-type buildings, several types of core were selected, damage state threshold was determined based on the capacity of structural members, and three-dimensional analyses were utilized. As a result, seismic fragility functions based on spectral acceleration were developed for various core locations and different shear strengths of the column stirrup. The fragility of piloti-type buildings significantly varied according to core location, an additional single wall, and whether the contribution of column stirrup was included or not. To estimate fragility more reasonably, it is necessary to prepare the parameters to reflect actual state well.

Regional Seismic Risk Assessment for Structural Damage to Buildings in Korea (국내 건축물 지진피해 위험도의 지역단위 평가)

  • Ahn, Sook-Jin;Park, Ji-Hun;Kim, Hye-Won
    • Journal of the Earthquake Engineering Society of Korea
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    • v.27 no.6
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    • pp.265-273
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    • 2023
  • This study proposes a methodology for the regional seismic risk assessment of structural damage to buildings in Korea based on evaluating individual buildings, considering inconsistency between the administrative district border and grid lines to define seismic hazard. The accuracy of seismic hazards was enhanced by subdividing the current 2km-sized grids into ones with a smaller size. Considering the enhancement of the Korean seismic design code in 2005, existing seismic fragility functions for seismically designed buildings are revised by modifying the capacity spectrum according to the changes in seismic design load. A seismic risk index in building damage is defined using the total damaged floor area considering building size differences. The proposed seismic risk index was calculated for buildings in 29 administrative districts in 'A' city in Korea to validate the proposed assessment algorithm and risk index. In the validation procedure, sensitivity analysis was performed on the grid size, quantitative building damage measure, and seismic fragility function update.