• Steel and Composite Structures
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• 제9권3호
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• pp.223-237
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• 2009

The present research aims to develop a methodology to rapidly assess bridges with damage to the superstructure, caused by overheight trucks or lower-than-average overhead clearance. Terrestrial laser scanning and image processing techniques are combined with the finite element method to arrive at an analytical model which is more accurate, with respect to the complex geometrical aspects of the bridge in its damaged configuration. ""Virtual load testing"" may subsequently be carried out on this analytical model to determine the reserve capacity of the structure in an objective manner.

• Smart Structures and Systems
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• 제12권6호
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• pp.661-678
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• 2013

In this paper, a wireless sensing system for structural field evaluation and rating of bridges is presented. The system uses a wireless platform integrated with traditional analogue sensors including strain gages and accelerometers along with the operating software. A wireless vehicle position indicator is developed using a tri-axial accelerometer node that is mounted on the test vehicle, and was used for identifying the moving truck position during load testing. The developed software is capable of calculating the theoretical bridge rating factors based on AASHTO Load and Resistance Factor Rating specifications, and automatically produces the field adjustment factor through load testing data. The sensing system along with its application in bridge deck rating was successfully demonstrated on the Evansville Bridge in West Virginia. A finite element model was conducted for the test bridge, and was used to calculate the load distribution factors of the bridge deck after verifying its results using field data. A confirmation field test was conducted on the same bridge and its results varied by only 3% from the first test. The proposed wireless sensing system proved to be a reliable tool that overcomes multiple drawbacks of conventional wired sensing platforms designed for structural load evaluation of bridges.

• 한국구조물진단유지관리공학회 논문집
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• 제17권6호
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• pp.70-76
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• 2013

본 연구에서는 강거더 연속교에 대해 국내외 설계기준에 규정되어 있는 활하중으로 인한 충격계수를 실험을 통해 검증하였다. 대부분의 도로교의 설계기준에서는 도로교의 경우 충격계수를 약 0.3 정도의 값으로 규정하고 있으나, 연속교의 경우에는 명확한 규정 및 명시가 없는 상황이다. 그러므로 단순교에 적용되는 충격계수를 연속교에 동일하게 적용하는 것이 일반적이다. 이 연구에서는 현장실험을 통해 연속교의 충격계수가 단순교에 적용되는 경우와 같이 사용될 수 있는지를 검증하였다. 현장실험 결과 얻어진 충격계수는 2차선 교량에서 1대의 만재트럭이 통과했을 경우 가장 하중이 많이 작용한 거더에서 0.2 이내의 충격계수가 계측되었으며, 2개의 차선을 통시에 만재트럭이 통과한 경우 그 충격계수는 0.05 이내의 값을 얻었다.

• 한국신뢰성학회지:신뢰성응용연구
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• 제13권4호
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• pp.241-252
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• 2013

Because of financial and safety concerns, there are needs for more accurate prediction of bridge behavior. Underestimation of the bridge load carrying capacity can have serious economic consequences, as deficient bridges must be repaired or rehabilitated. Therefore, the knowledge of the actual bridge behavior under live load may lead to a more realistic calculation of the load carrying capacity and eventually this may allow for more bridges to remain in service with or without minor repairs. The presented research is focused on the reliability evaluation of the actual load carrying capacity of existing bridges based on the field testing. Seventeen existing bridges were tested under truck load to confirm their adequacy of reliability. The actual response of existing bridge structures under live load is measured. Reliability analysis is performed on the selected representative bridges designed in accordance with AASHTO codes for bridge component (girder). Bridges are first evaluated based on the code specified values and design resistance. However, after the field testing program, it is possible to apply the experimental results into the bridge reliability evaluation procedures. Therefore, the actual response of bridge structures, including unintentional composite action, partial fixity of supports, and contribution of nonstructural members are considered in the bridge reliability evaluation. The girder distribution factors obtained from the tests are also applied in the reliability calculation. The results indicate that the reliability indices of selected bridges can be significantly increased by reducing uncertainties without sacrificing the safety of structures, by including the result of field measurement data into calculation.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.21-24
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• 2007

This paper deals with introduction of testing equipments for the evaluation of dynamic tensile characteristics of auto-body steel sheets and the crashworthiness of auto-body members. The servo-hydraulic high speed material testing machine was developed for tensile tests at the intermediate strain rate to obtain the tensile material properties at the strain rate under 500/sec. The split Hopkinson bar apparatus using the elastic wave was developed for dynamic material characteristics at the high strain rate ranged from 1,000 to 10,000/sec. The servo-hydraulic high speed crash testing machine is the equipment for the evaluation of the collapse load and crashworthiness of auto-body members. High speed carrying truck crashes to specimen with the maximum velocity of 17 m/sec.

• Structural Engineering and Mechanics
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• 제82권1호
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• pp.69-79
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• 2022

This paper discusses the field testing of two single-span double-tee girder (DTG) bridges in South Dakota to determine live load distribution factors (LLDFs) and the dynamic load allowance (IM). One bridge had seven girders and another had eight girders. The longitudinal girder-to-girder joints of both bridges were deteriorated in a way that water could penetrate and the joint steel members were corroded. A truck traveled across each of the two bridges at five transverse paths. The paths were tested twice with a crawl speed load test and twice with a dynamic load. The LLDFs and IM were determined using strain data measured during the field tests. These results were compared with those determined according to the AASHTO Standard and the AASHTO LRFD specifications. Nearly all the measured LLDFs were below the AASHTO LRFD design LLDFs, with the exception of two instances: 1) An exterior DTG on the seven-girder bridge and 2) An interior DTG on the eight-girder bridge. The LLDFs specified in the AASHTO Standard were conservative compared with the measured LLDFs. It was also found that both AASHTO LRFD and AASHTO Standard specifications were conservative when estimating IM, compared to the field test results for both bridges.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.201-208
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• 2004

To substitute conventional reinforced-concrete bridge deck, glass composite precast bridge deck - Delta Deck/sup TM/, which possesses advantages of light weight, high strength, corrosion resistance and durability, is developed for the DB24 truck load. Pultruded composite bridge deck is designed and fabricated. To verify serviceability and structural safety, finite element analysis, structural testing such as flexural test, local fatigue test, flexural fatigue test and field tests are conducted. In this paper structural characteristics of developed deck and its field application in Korea is presented.

• Structural Engineering and Mechanics
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• 제6권3호
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• pp.259-274
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• 1998

The test results from non-destructive and destructive field testing of a three-span deteriorated reinforced concrete slab bridge are used as a vehicle to examine the reliability of available tools for finite-element analysis of in-situ structures. Issues related to geometric modeling of members and connections, material models, and failure criteria are discussed. The results indicate that current material models and failure criteria are adequate, although lack of inelastic out-of-plane shear response in most nonlinear shell elements is a major shortcoming that needs to be resolved. With proper geometric modeling, it is possible to adequately correlate the measured global, regional, and local responses at all limit states. However, modeling of less understood mechanisms, such as slab-abutment connections, may need to be finalized through a system identification technique. In absence of the experimental data necessary for this purpose, upper and lower bounds of only global responses can be computed reliably. The studies reaffirm that success of finite-element models has to be assessed collectively with reference to all responses and not just a few global measurements.

• 한국구조물진단유지관리공학회 논문집
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• 제7권3호
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• pp.139-146
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• 2003

본 연구는 기지하중을 이용하여 교량의 효율적 평가를 하기 위한 것이다. 계산상 내하력이 부족한 것으로 평가된 교량의 하중저항능력은 기존의 방법에 의한 평가능력을 상회하는 경우가 일반적이다. 기지하중을 이용한 실험은 미지의 저항능력을 평가할 수 있으며, 따라서 대상교량의 하중저항능력을 정확히 검증할 수 있다. 실험을 위한 기지하중은 일반적인 통행하중보다 큰 것을 사용하여야 한다. 따라서 본 연구에서는 미시간 주에서는 법적으로 허용된 11축 트럭 하중(685kN)을 고려하여, 두 대의 군용탱크와 두 대의 11축 트럭을 이용하였으며, 실험의 안전을 위하여 재하하중의 크기를 점진적으로 증가하면서 계측을 실시하였다. 실험에 의한 대상 교량의 응력수준은 계산에 의한 값보다 다소 작게 측정되었으며, 이는 부적절한 재료강도의 예측, 파라펫이나 가드레일과 같은 비구조요소의 기여, 지지조건의 변화 등에 기인한 것으로 분석되었다.

• Geomechanics and Engineering
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• 제11권5호
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• pp.625-638
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• 2016

This paper presents field study and numerical modeling results for a single-cell low-fill concrete box culvert under a flexible pavement subjected to traffic loading. The culvert in the field test was instrumented with displacement transducers to capture the deformations resulting from different combinations of static and traffic loads. A low-boy truck with a known axle configuration and loads was used to apply seven static load combinations and traffic loads at different speeds. Deflections under the culvert roof were measured during loading. Soil and pavement samples were obtained by drilling operation on the test site. The properties of the soil and pavement layers were determined in the laboratory. A 3-D numerical model of the culvert was developed using a finite difference program FLAC3D. Linear elastic models were used for the pavement layers and soil. The numerical results with the material properties determined in the laboratory were compared with the field test results. The observed deflections in the field test were generally smaller under moving loads than static loads. The maximum deflections measured during the static and traffic loads were 0.6 mm and 0.41 mm respectively. The deflections computed by the numerical method were in good agreement with those observed in the field test. The deflection profiles obtained from the field test and the numerical simulation suggest that the traffic load acted more like a concentrated load distributed over a limited area on the culvert. Elastic models for culverts, pavement layers, and surrounding soil are appropriate for numerical modeling of box culverts under loading for load rating purposes.