• Structural Engineering and Mechanics
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• 제86권6호
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• pp.715-730
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• 2023

Broad studies have addressed the issue of structural element damage identification, however, rubber bearing, as a key component of load transmission between the superstructure and substructure, is essential to the operational safety of a bridge, which should be paid more attention to its health condition. However, regarding the limitations of the traditional bearing damage detection methods as well as few studies have been conducted on this topic, in this paper, inspired by the model updating-based structural damage identification, a two-stage bearing damage identification method has been proposed. In the first stage, we deduce a novel bearing damage localization indicator, called element relative MSE, to accurately determine the bearing damage location. In the second one, the prior knowledge of bearing damage localization is combined with sailfish optimization (SFO) to perform the bearing damage estimation. In order to validate the feasibility, a numerical example of a 5-span continuous beam is introduced, also the noise robustness has been investigated. Meanwhile, the effectiveness and engineering applicability are further verified based on an experimental simply supported beam and actual engineering of the I-40 Bridge. The obtained results are good, which indicate that the proposed method is not only suitable for simple structures but also can accurately locate the bearing damage site and identify its severity for complex structure. To summarize, the proposed method provides a good guideline for the issue of bridge bearing detection, which could be used to reduce the difficulty of the traditional bearing failure detection approach, further saving labor costs and economic expenses.

• Earthquakes and Structures
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• 제11권5호
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• pp.841-859
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• 2016

Bridge bearings are important connection elements between bridge superstructures and substructures, whose health states directly affect the performance of the bridges. This paper systematacially presents a new method to identify the bridge bearing damage based on the neural network theory. Firstly, based on the analysis of different damage types, a description of the bearing damage is introduced, and a uniform description for all the damage types is given. Then, the feasibility and sensitivity of identifying the bearing damage with bridge vibration modes are investigated. After that, a Radial Basis Function Neural Network (RBFNN) is built, whose input and output are the beam modal information and the damage information, respectively. Finally, trained by plenty of data samples formed by the numerical method, the network is employed to identify the bearing damage. Results show that the bridge bearing damage can be clearly reflected by the modal information of the bridge beam, which validates the effectiveness of the proposed method.

• 한국공간구조학회논문집
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• 제19권4호
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• pp.77-84
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• 2019

This study introduces a newly developed PC non-bearing wall system to prevent the damage of RC wall-type apartments that have been heavily damaged by the 2017 Pohang Earthquake. In order to evaluate the performance of the developed PC non-bearing wall system, a static cyclic test is conducted. The prototype of test specimen is from the RC wall-type apartment which has been severely damaged by the 2017 Pohang Earthquake. The specimen with the conventional non-bearing wall system showed the similar damage of RC wall type apartment suffered from the Pohang Earthquake. In case of the specimen with the developed PC non-bearing wall system, cracks and damages were not transmitted between the walls due to the seismic slit and there were almost no cracks in the non-bearing walls. Therefore, the proposed non-bearing wall system, separated from the structural walls, could prevent spreading cracks to bearing walls and make it possible to effectively control damage due to earthquake loads.

• Communications for Statistical Applications and Methods
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• 제12권2호
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• pp.381-394
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• 2005

In order to estimate the damage of orchards due' to natural disasters such as typhoon, severe rain, freezing or frost, it is necessary to estimate the number of fruit bearing before and after the damage. To estimate the fruit bearing after the damages are easily done by delegations, but it cost too high to survey every insured farm household and calculate the fruit bearing before the damage. In this article, we suggest to use a random coefficient model to predict the numbers of fruit bearing in the orchards before the damage based on the tree age and the area information.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.461-462
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• 2002

Rolling element bearing fatigue life can be significantly reduced by debris particles in lubricants. The debris particles cause raceway surface dents that initiate early fatigue damage. Optical interferometry has been found to be the best method for characterizing bearing raceway debris dent damage. This technique is used to determine the important features, sizes and density of dents. The resulting data file is then used to determine bearing fatigue life. Tests show that bearings manufactured by different processes and material types are affected differently by debris damage and that these differences must be considered by life prediction methodologies. Bearings made by a specific enhanced process can significantly resist the deleterious effects of debris damage and outperform bearings made by other means.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
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• pp.287-294
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• 2001

Dynamic responses of multi-span simply supported bridges are investigated to examine the effect of damaged bearings under seismic excitations. The damaged bearings are modeled as sliding elements with friction between the super-structure and the pier top. Various values of the friction coefficients for damaged bearings are examined with increasing magnitudes of peak ground accelerations. It is found that the g1oba1 seismic behaviors are significantly influenced by the occurrence of bearing damage. It should be noticed that the most possible location of unseating failure of superstructures differs with that in the model without consideration of the bearing damage. It can be concluded that the bearing damage may play the major role in the unseating failure of a bridge system, so that the damage of bearings should be included to achieve more rational seismic safety evaluation.

• 대한기계학회논문집A
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• 제37권11호
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• pp.1315-1321
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• 2013

볼 베어링의 손상 상태를 예측하기 위한 방법을 본 논문에서 제시하였다. 손상 진전율을 추정하기 위해 확률적 베어링 피로 결함 진전 모델을 적용하고 잡음이 포함된 가속도 신호의 RMS 데이터를 이용하여 손상 상태와 고장 시간을 계산하였다. 확률적 결함 진전 모델의 파라미터는 볼 베어링에 대한 일련의 Run-to-Failure 시험을 수행하여 결정하였다. 가속도 RMS값으로부터 손상 진전율과 손상 상태를 추정하기 위해 규칙화된 파티클 필터 추정 방법을 적용하였다. 미래 시점에서의 손상 상태는 최근 측정된 데이터와 직전에 추정된 상태값을 이용하여 예측하였다. 예측된 손상 상태와 시험 데이터와 비교하여 개발된 방법의 적절성을 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1727-1732
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• 2004

For the purpose of monitoring by ultrasonic test of the ball bearing conditions in rotating machinery, a system for their diagnosis was developed. ultrasonic technique is used to detect abnormal conditions in the bearing system. And various data such as frequency spectrum, energy and amplitude of ultrasonic signals, and ultrasonic parameters were acquired during experiments with the simulated ball bearing system. Based on the above results and practical application for power plant, algorithms and judgement criteria for diagnosis system was established.

• 한국지진공학회논문집
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• 제6권5호
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• pp.19-27
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• 2002

본 연구에서는 지진하중을 받는 교량구조물의 동적거동을 보다 실제적으로 예측하기 위하여 받침의 손상여부는 물론 다양한 영향요소를 고려할 수 있는 이상화된 다자유도 교량해석모형을 개발하였으며, 이를 바탕으로 받침의 손상이 교량구조물의 지진응답에 미치는 영향을 분석하였다. 받침의 손상은 마찰요소를 이용한 단순화된 모형으로 고려하였으며, 발생가능한 받침의 손상조건에 따른 영향을 분석하기 위하여 다양한 마찰계수의 적용에 따른 교량구조물의 응답분포특성을 구하였다. 모의분석 결과로부터 받침손상의 고려여부 및 적용된 마찰계수에 따라 최대응답의 크기 및 발생위치가 서로 다르게 평가되었으며, 특히 교량구조물에서 낙교의 발생가능성이 큰 위치에서의 최대상대거리는 받침의 손상여부에 따라 상당한 영을 받는 것으로 나타났다. 그러나 최대응답의 증가량은 크지 않은 것으로 분석되었다. 그러므로 다경간 단순형 교량구조물에 있어서 받침의 손상에 따른 낙교의 발생가능성을 감소시키기 위한 부가적인 받침보강은 필요시 선택적으로 적용될 수 있을 것으로 판단된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1999년도 춘계학술대회 논문집
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• pp.367-374
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• 1999

The selection of geogrid types for the use of reinforced rail roadbed is important in the design of railways. Also, the problem of the construction damage on the geogrid during construction is raised by the field engineers. Therefore, laboratory model tests were peformed to investigate the efficiency of the bearing capacity and construction damage. As a result, it was found that the bearing capacity of the rigid geogrid reinforced railroad ballast shows 1.54 times higher than that of the flexible geogrid reinforced case. In addition, there were no noticeable damage during construction.